International breeding trends and the most important new cultivars of nuts

9. International breeding trends and the most important new cultivars of nuts

Author: Géza Bujdosó

Walnut ( Juglans regia L.)

9.1. A brief history of walnut breeding

The genus Juglans incorporates 21 species which can be found almost all over the world. The most important of these species is Juglans regia L., therefore in this chapter we discuss about this species only.

Juglans regia is native in the mountain forests of Central Asia, can be found in Xinjiang region of Western China, in some territories of Kazakhstan, Uzbekistan and Southern Kyrgyzstan, as well as from mountain areas of Nepal, Tibet, Northern India and Western Pakistan through Afghanistan, Turkmenistan and Iran until even Azerbaijan, Armenia, Georgia and in some regions of Eastern Turkey. There are some residual walnut populations of Iranian and Eastern Turkish origin from old times in Eastern Europe and in countries of the Balkan Peninsula, they got there by ancient Greek merchants and settlers (Zohary and Hopf, 1993, Terpó 1976). Walnut was called Jupiter’s seed in the ancient Rome, this is the origin of the genus name Juglans. Ancient Romans continued to spread walnut in Europe: after Italy it became known in France, Spain, Portugal and in Southern Germany (Leslie and McGranahan, 1998). English settlers took the first walnut trees to the territory of the present USA in 1562, this is the origin of the naming „English walnut”, as Juglans nigra L. is the native species in North America (McGranahan and Leslie 2009).

Folk selection is considered to be the first step of breeding, when genotypes with a lot of good features were started to propagate, but unfortunately, generatively. As walnut cultivars (scion) cannot be propagated from seed, therefore a number of valuable genotypes were lost because of generative propagation. First “cultivars” selected in the Carpathian Basin were widely known: Sebeshelyi gömbölyű, Sebeshelyi hosszú and Milotai had an outstanding fruit quality.

In the former Yugoslavia, walnut cultivar assortment developed quite uniquely. Walnut breeding started at the Novi Sad University in 1962, where mostly walnut trees from Vojvodina province were evaluated and valuable genotypes were collected for further examinations. It turned out soon, that a wider sample collection would be necessary, therefore a contest was announced in 1973 under the title “Looking for quality walnuts”. This “folk selection” provided base for the walnut cultivar assortment of the former Yugoslavia, as samples arrived not only from Vojvodina province, but from the whole country (Korac et al 1986).

At the beginning of the conscious Hungarian walnut breeding in 1910, the Ministry of Agriculture imported a high quantity of seeds of the major French cultivars. Seedlings were planted to different growing areas of the country, and the evaluation of the population was carried out in the 1950’s. It was determined, that “populations originating from the French walnut race are not adaptive enough to the habitat conditions of the domestic Carpathian race” (Szentiványi 1998). At this point the importance of Hungarian walnut breeding was recognized. Hungarian walnut breeding was started by Aladár Porpáczy Sr. in the predecessor of the Research Institute for Fruit Growing and Ornamentals in Fertőd. This work continued from 1950 in Érd, in the predecessors of the Research Institute for Fruit Growing and Ornamentals (RIFO). Péter Szentiványi created here the cultivars Alsószentiváni 117, Milotai 10 and Tiszacsécsi 83 by landscape selection, which were approved by the state. ’Tiszacsécsi 2’, which was also created by landscape selection, was later withdrawn.

In walnut producing countries situated east of Hungary (Ukraine, Romania), landscape selection is very popular, because genetic variability of walnut populations originating from the Carpathian race is very high. As a result of this, almost all cultivars approved by the state were created by landscape selection. These varieties are suitable for safe and successful cultivation under the ecological conditions of the place of selection. This is important to keep in mind, because ecological adaptability of walnut is very low, it hardly tolerates significantly different ecological conditions (Szentiványi 2006).

In the 1970’s, cross-breeding was also used beside landscape selection in the Hungarian walnut breeding program. Variety ‘Pedro’, bred at the University of California, Davis was involved in hybridization as the male partner. Almost all recent Californian cultivars (’Tehama’, ’Serr’, ’Vina’) were used during cross-breeding in the Research Institute of Érd, but only ‘Pedro’ inherited its traits well, therefore Péter Szentiványi continued his work solely with this variety. Prof. Szentiványi created the cultivars ‘Milotai bőtermő’, ‘Milotai kései’ and ‘Milotai intenzív’ by crossing ‘Milotai 10’ and ‘Pedro’. By crossing ’Alsószentiváni 117’ and ’Pedro’, cultivars Bonifác and Alsószentiváni kései were created. Variety ‘Tiszacsécsi 83’ having biotic and abiotic tolerance was used with great expectations in the cross-breeding program, but no promising genotypes were obtained from ’Tiszacsécsi 83’ x ’Pedro’ combinations.

In the USA, at the University of California, Davis, cross-breeding is performed almost excusively, and cultivars bred there (‘Chandler’, ‘Howard’ and ‘Sunland’) became the leading walnut varieties of countries with Mediterranean climate (Hendricks et al 1998).

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Fig 9.1. Artificially pollinated female flower (Photo: Bujdosó)

There were no cultivars certified by state bred by mutation, which is probably in connection with the fact, that walnut has a weak mutation tendency.

Some genotypes were created by a biotechnological method called gene transfer at the University of Davis, but their cultivation is not approved yet. According to their concept, this method can help to reduce the allergen content of the kernel, modify the time of budtake and the canopy habit, as well as improve winter hardiness and stress tolerance to cold and heat (Gauthier and Jacobs 2011, Vahdati et al. 2002). Mapping of the genes coding the biosynthesis of tannin, unsaturated fatty acids and flavonoids is still in progress (McGranahan and Leslie 2009). In addition, Bacilus thuringiesnsis is used to achive resistance against insect pests (Leslie et al. 2001) and Agrobacterium species of walnut (Escobar et al. 2002).

It is not easy to assess the possibility of naturalization in case of walnut cultivars. Naturalization seems to be successful only in areas, where ecological conditions are the same or similar to those of the breeding site of the cultivar in question. This fact underlines the importance of domestic adaptation examinations of foreign walnut cultivars before their involvement into cultivation. Hungarian growers have bought propagation material from abroad beacuse of the shortage in walnut grafts. Growers bought mostly variety ‘Jupiter’ bred in the former Czechoslovakia, but the seed became dark in Hungary. This phenomenon is associated probably with the drier and warmer weather in Hungarian summer. The naturalization of the Californian ‘Hartley’ was not successful as well in Hungary, because this variety has a longer vegetation period and a higher temperature need than Hungarian cultivars, therefore develops small, thin and not so aesthetic kernels (Bujdosó 2003). It has to be mentioned, that we have no experiences under irrigated circumstances in respect of any varieties. Naturalization of the Californian cultivar ‘Pedro’ can be considered as successful, so it was included in the Hungarian National Variety List. However, we have to keep in mind, that its leafing-out time is medium early (between 15-20 April), therefore it is recommended for cultivation only in areas protected against late spring frosts.

If we look at the successful examples of naturalization in the world, Californian walnut cultivars can be mentioned (‘Chandler’, ‘Howard’, ‘Serr’), which are effectively cultivated outside the USA in countries with mediterranean climate, in Spain as well as in ecologically suitable areas of Australia and New Zealand.

Hungarian walnut cultivars are also successfully naturalized in the central and northern parts of Germany. It worth mentioning, that the pericarp (nut shell) is thinner there, so these cultivars require a more careful harvest and post-harvest handling. Hungarian cultivars are more susceptible to walnut pathogens in North and Central Germany (in North Germany only the three basic, landscape selected varieties are popular), and they are positively commented in Bulgaria and Armenia as well.

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Fig 9.2 GMO walnut genotypes held in an isolated cultivation system at the University of Davis (Photo: Bujdosó)

9.2. Major aims of breeding

Previously the most important aims of breeding were late leafing and fruiting on lateral buds in all walnut producing countries. Today a third aim joined to these two: early maturation. In spite of the fact, that the main marketing period of walnut is before Christmas on the northern hemisphere, earlier market entry is considered to be important recently in major walnut producing countries (USA, France, Romania) regarding in-shell walnuts and walnut kernels as well.

Naturally, good fruit quality is essential. The lower limit of 1st grade is 32 mm in diameter at present. A round or globose walnut shape is also required. Genotypes with elongated shape are less preferred, as their diameter does not reach 32 mm. It is important, that the pericarp should be smooth and light in colour, and the kernel should be light in colour or slightly striated by dark brown. In addition, the major characteristics of an ideal walnut cultivar are a 40% kernel rate, easy to crack and clean, a good taste without other flavours or aftertaste, and a properly closed suture. As walnut is cultivated in a highly increasing quantity on the southern hemisphere as well, and the harvest from there comes to Europe in March-April, it is more and more important, that the kernel should preserve its light colour as long as possible. Regular and high yield, good propagation ability and medium growth habit are also essential.

In the largest cross-breeding program of the world at the University of Davis, the criteria of an ideal walnut cultivar were determined in 2009 as follows (McGranahan and Leslie 2009):

1. late leafing,

2. precocity (high early yield), a minimum of 500 kg dried in-shell walnuts per ha in the 4th leaves,

3. lateral fruitfulness beside apical fruitfulness,

4. tendency to alternative fruit development (apomixis is beneficial, but parthenocarpy is not preferred, as these walnut fruits do not contain kernel),

5. a minimum of 0,6 t/ha dried in-shell yield at maturity,

6. resistance against/tolerance to major pathogens of walnut,

7. the harvest period must end before the beginning of October,

8. smooth shell surface, easy breaking and cleaning, a kernel rate not more than 50%, the fruit should reach a diameter of 30 mm, light coloured kernel, a kernel weight between 8-9 g, easy breaking to half kernels,

9, moderately vigorous growth habit.

There are huge plant protection problems in walnut production at present, which are due mostly to Xanthomonas arboricola pv. juglandis, as well as to BAN (Brown Apical Nekrosis). Many breeding groups of the world address these problems, but unfortunately, there are no cultivars tolerant or resistant against walnut blight caused by Xanthomonas yet. According to researchers, tolerant cultivars can be created, if genotypes showing tolerance/resistance against this pathogen are selected from local populations (Rovira et al. 2007, Özaktan et al. 2007, 2008; Lovera et al. 2008, Solar et al. 2008; Tsiantos et al. 2008, Ruiz-García et al. 2009, Solar et al. 2009, Frutos and López 2012). We have to mention, that simultaneously with international research trends, examination of Hungarian walnut cultivars and some walnut genotypes selected in Transylvania against Xanthomonas is carried on at the Corvinus University Budapest, Department of Pomology (Thiesz et al. 2007).

9.3 Genetic sources of breeding

Beside Juglans regia L. (2n=32), species Juglans nigra L. and Juglans hindsii Rehd. are frequently used in breeding programs in the USA (McKenna and Epstein 2003). In China, the major gene sources beside Juglans regia are Juglans mandshurica Maxim, Juglans cathayensis Dode. having outstanding drought tolerance, cold tolerance and winter hardiness and Juglans sigillata Dode. with good tolerance to warm and humid climate, but poor winter hardiness (Tian et al 2009).

Hungarian walnut breeding is in a favored position, as a small population of the Carpathian race is present in the country. A very high genetic diversity can be observed in this population, and this is one of the reasons of the outstanding results in Hungarian breeding. On the one hand, Hungarian walnut cultivar assortment is the most precocious on the northern hemisphere, preceding other walnut producing countries by 10-14 days. Reaching this precocity is the aim in a number of foreign breeding programs. On the other hand, Hungarian walnut cultivars are otstanding because of their biggest fruit size, thus representing a premium product value.

The appearance and cultivation of interspecific hybrids is a feature mostly of California State, where the rootstock ’Paradox’ was created as a Juglans regia x Juglans hindsii hybrid (McGranahan and Leslie 2009). McKenna and Epstein (2003) draws attention to the fact, that the name ’Paradox’ stands not always for a population originating from the same parent partners. The rootstock ’Paradox’, available on the market can be the interspecific hybrid of Juglans hindsii and Juglans major or Juglans hindsii and Juglans nigra.

According to examination results of more authors, in case of using interspecific hybrids as rootstocks it is highly important to know the parent species. Interspecific hybrids created with Juglans nigra are more susceptible to Agrobacterium root gall in California, than those created from Juglans regia, Juglans hindsii and Juglans major populations. In addition, rootstock cultivars ’butterjaps’ (syn.: ’buartnuts’), from the crossing between Juglans cinerea and Juglans ailantifolia, as well as ‘Leslie Burt’ from the crossing between Juglans nigra and Juglans ailantifolia are also susceptible to the walnut Xanthomonas disease in California (McKenna and Epstein 2003, McGranahan and Leslie 2009).

The significance of interspecific hybrids is important in case of scion cultivars in the protection against Cherry Leafroll potyvirus (CLRV), as onlyJuglans hindsii contains a dominant gene, which induces a hypersensitive reaction in walnut after viral infections. In back-crossings of Juglans hindsii x Juglans regia hybrids with Juglans regia, American researchers found hypersensitive and tolerant genotypes in a 1:1 ratio in progeny populations. We have to note regarding these interspecific hybrids, that they are male flowers are sterile, therefore it is an open question at present, how these genotypes showing hypersensitivity against CLRV bear fruit, or whether hypersensitive reaction works in open field or not (McGranahan et al. 1997).

In China, the most popular interspecific hybrid is Juglans hopeiensis Hu, found in Taihang mountains in Hebei province, which is a natural hybrid of J. regia x J. mandshurica. This species is not only significant as a fruit (with large fruit size, attractive look), but it is used as an ornamental plant as well (Wu et al 2009).

9.4 Lateral fruitfulness and improvement of fruit quality

One of the most important characteristic for growers is the fruitfulness on lateral buds, which can increase the yield compared to cultivars bearing fruit only from apical buds. To achieve this aim, cultivar ‘Pedro’ was involved in the cross-breeding program in Hungary as a male partner. Additional advantages of this variety are its light-coloured and smooth shell and light-coloured kernel.

Fruit bearing in clusters has appeared at some novel bred cultivars, which means, that apical buds develop not only one fruit, but a fruit group of 5 to 12 fruits resembling a cluster of grapes. Fruits in the cluster are usually small, so only a few cluster-fruiting cultivars approved by the state can be found in the cultivar assortment of walnut producing countries. A positive example is variety ‘Tisza’ bred in Serbia, whose clusters contain 7-9 fruits of 30-33 mm in diameter each. Another disadvantage of walnut cultivars with cluster fruiting is the low yield per tree. ‘Tisza’ is an exception also in this respect with its high fruitfulness.

In the Californian walnut breeding program, cultivar ‘Payne’ was used as a parent partner to improve fruitfulness, and varieties Vina, Serr, Howard and Chandler were bred (Ramos, 1998). Nowadays three other new cultivars were selected as a result of breeding (Sextont, Gillet, Forde), the spreading of these started a few years ago. All newly bred varieties are less susceptible to the Xanthomonas disease of walnut, bear fruits on lateral buds, high-yielding, early ripening and have a good kernel quality.

Recently, there is an increasing demand for walnut cultivars with red kernel. For the time being, there is only a few red-kernel walnut cultivars can be found in the assortment. In Europe there are no such varieties in the production, breeders keep it in gene bank collections. In California, ‘Robert Livermore’ is the only red-kernel cultivar, grown only in a small surface (McGranahan and Leslie 2004).

9.5 Research concerning walnut pathogenes

The breeding of walnut genotypes tolerant or resistant against pathogens Xanthomonas arboricola pv. juglandis and BAN (Brown apical necrosis) has started in different breeding centers of the world. BAN disease is caused jointly by Xanthomonas arboricola pv. juglandis and Gnomonia leptosyla, as well as other Alternaria and Fusarium species. The development of an open field protection effective against both diseases is still carried on. The CUB Department of Pomology and the Research Institute for Fruit Growing and Ornamentals in Érd are also involved in this work, while they have made surveys in the largest Hungarian walnut plantatition concerning the spreading of both diseases and the efficiency of the chemical protection against them.

Researchers agree, that the occurrence of Xanthomonas is closely related to the physiological state of walnut trees, namely to their water and nutrient supply. In plantations where water and nutrient supply is unfavorable or dry periods are frequent, Xanthomonas is more common compared to normally supplied plantations (Parveaud et al. 2009). According to Chevallier et al (2009), the behaviour of different walnut cultivars against bacterium Xanthomonas is closely related to their hydroxy-cinnamic acid derivative and flavonoid content. Both compounds are produced in the walnut tree in case of infection, but only by a sufficient water supply during the vegetation period.

According to examination results, the bacterium Xanthomonas arboricola pv. juglandis reaches a concentration between 103 and 10 7 at flowering, therefore chemical protection should be started at this time (Giraud et al 2009). An innovative way of protection, according to Chevallier and Laymajoux (2009), if the copper-containing active substance is spread out in a chelate form, this way less copper is used more effectively. According to the results of Jenkins et al. (2009), an efficient solution is, if bacteriophagous strains are used for protection against this pathogen. Süle et al. (2007) note, that different Xanthomonas arboricola pv. juglandis strains behave differently against bactericid products with various active substance and concentration.

Beside Xanthomonas, Agrobakterium tubefaciens causes serious problems in some countries with mediterranian climate, and the interspecific rootstock variety ‘Paradox’ is not tolerant to this pathogen. According to recent results, walnut cultivars Chandler, Vina and Serr grown on their own root are less susceptible to this pathogen in California (Hasey et al 2009).

9.6 Breeding programs and cultivar use of major walnut producing countries

Since the 1970’s and 80’s, in almost all major breeding centers of the world, breeders are trying to create early ripening cultivars that are in high proportion lateral bearers. A lot of new cultivars were involved in cultivation at the end of the 1990’s and the beginning of the 2000’s. Nowadays novel bred cultivars are not spreading, which has two reasons. On one hand, there are problems about the nursery propagation of new cultivars, a significantly lower nursery yield can be reached, than in case of traditional cultivars, therefore propagation material is hard and expensive to produce. On the other hand, growers had to face the fact, that newly bred cultivars, that are in high proportion lateral bearers, are usually more susceptible to walnut Xanthomonas disease than basic cultivars, so optimal production site selection, special competence, as well as a precise plant protection technology is needed for their growing. Because of these two reasons, growers prefer old, established cultivars thoughout the world.

In China, which is the largest walnut producting country in the world, breeders created their own assortment. The major breeding goal was to improve taste. Chinese walnut breeding can be regarded as successful, as there are 28 cultivars bred by landscape selection, and other 30 cross-bred cultivars in the country’s variety assortment. The huge number of cultivars is closely related to the large territory and diverse ecological conditions of the country. Chinese researchers can recommend cultivars to almost all major walnut producing regions. Examples are cultivar ‘Xinjiang’ which can be grown in Peking, Hebei, Shanxi and Shandong provinces, as well as ’Liaohe 1’ can successfully be produced on Taihang hills, while ’Yuanfeng’ on Qin-Ba mountains. The open-minded class of the society, probably educated abroad, has an increasing need for dried in-shell walnuts and kernels as a dessert, therefore genotypes with pleasing shell and kernel features beside good taste are continuously spreading.

Chinese walnut cultivars have a number of features incredible for us. The yield security of ’Qinquan 1’ is outstanding, as a half or almost total yield can be expected even after late spring frosts, because its apomictic tendency is between 48-75%.

In California, walnut growing is a successful sector. Owing to this, a lot of universities started walnut breeding programs througout the country. Today’s main cultivar is Chandler, which ripens at the end of September, has a 28-30 mm in diameter, the shell is light-coloured, its surface is slightly striated, the kernel is light yellow or light brown. A special value of the cultivar, that the kernel keeps its outstanding colour for 10-12 months. Bringing its ripening time earlier from the end of September became the first breeding goal at the University of Davis.

Turkish walnut cultivation is based on the selection of the country’s genotypes. The most significant cultivar is ‘Kaplan 86’ ripening at the end of September, whose fruit weight is 24-25 g, the kernel weight is around 10 g, and has high quality fruits. ‘Altnova’ (ripening in the middle of September), ‘Yalova 1’ (end of September) and ‘Yalova 4’ (beginning of October) have dark kernel, so they are less attractive. Some Turkish universities have walnut breeding programs in progress, their main goal is outstanding fruit quality.

The fourth largest walnut producing country of the world is Iran, where foreign cultivars, mostly American (’Serr’, ’Chandler’) and French (’Lara’) varieties are grown in modern, irrigated plantations. According to Arabic dietary habits, high quality dried kernels are demanded all year round.

Ukraine has a distinguished place in the world’s walnut production. Major breeding goals are late leafing, early ripening and outstanding fruit quality. The most important Ukrainian cultivars completely fulfil these goals, their descriptions can be seen below. However, propagation of the Ukrainian cultivars is difficult, therefore their spreading is slow, almost unsolved.

Romania is also a significant walnut growing country, where University of Craiova performs its own walnut breeding program. Primary breeding goals in the country are early ripening, late leafing and outstanding fruit quality. In Oltenia (South Carpathians), the following new cultivars proved to be the best: Valcor, Jupanesti, Valrex and Valmit. A disadvantage is, that their shell is thinner, requiring a more careful machine harvest and handling. At the beginning of the 2000’s, a walnut breeding work started at the Sapientia Hungarian University of Transylvania, aiming at the exploration of the walnut growing values and valuable genotypes of the traditional walnut cultivating region, Háromszék. Romanian walnut cultivars are spreading hardly because of the uncoordinated nursery demand and supply. This is the reason, why attention is directed towards Hungarian cultivars, mostly in Transylvania, but serious winter frost damages were experienced in the case of hybrid walnut cultivars.

French walnut cultivation and research are highly appreciated around the world. At present the research is focused on the development of cultivation technology of newly bred walnut cultivars. French walnut breeding has created a number of valuable cultivars, which are in a high rate lateral bearers and have outstanding fruit quality (light-coloured and smooth shell, light-coloured kernel). Recently there is a high interest about cultivars ‘Fernor’ (outstanding market value) and ‘Lara’ (high yield).

India joined the 10 most important walnut producing countries of the world some years ago, as there is a significant walnut cultivation in Kashmir province. Indian walnut growing is based on local varieties, which are of poor quality, so less competitive on the world market.

The countries of the southern hemisphere have to be mentioned as well, where there is an increasing interest about walnut cultivation. Walnut is grown on habitats with mediterranean climate in almost all countries, therefore Californian cultivars are popular, mainly ’Chandler’ and ’Serr’. Australian farmers aim at fresh consumption, therefore the selection of attractive cultivars having outstanding shell and kernel features is primary for them. The cultivation rate of Californian walnut cultivars is high in New Zealand, South Africa, Chile and Argentina as well.

In Slovenia, a significant walnut research is carried out at the University of Ljubljana, where the Slovenian cultivar assortment was bred. Earlier, in the 1980’s, ’Erjavec’ proved to be the cultivar with the best market value, so this was cultivated in a high proportion. Today, newly bred varieties (’Zdole-59’, ’Zdole-60’, ’Zdole-62’) with late leafing are not spreding quite fast, as they have a smaller fruit size than standard ’Erjavec’. In Bulgaria, walnut breeding is performed at the Fruit Growing Research Institute of Plovdiv, we recommend some of their cultivars for trying.

An increasing interest can be observed about walnut cultivation in the countries of Central Asia: Azerbaijan, Uzbekistan, Tajikistan, Kirgisistan and Kazakhstan. Almost all Central Asian countries have their own cultivar assortment. The primary breeding aim is to improve fruit quality and to reach resistance/tolerance to major walnut diseases. In Azerbaijan, walnut breeding is carried out at the Azerbaijan State Agricultural University. More than 20 cultivars were bred in Tajikistan.

9.7 Walnut cultivar use in Hungary

According to the data of the Hungarian Central Statistical Office, 40% of Hungarian walnut plantations were of cultivar ‘Milotai 10’, and 21% of ’Alsószentiváni 117’ in 2001. The third walnut cultivar in plantations is ‘Tiszacsécsi 83’ with a rate of 7%.

There is an increasing demand for new hybrid walnut cultivars from the growers’ side, but their spread is difficult. Cultivation of hybrid varieties requires the strict compliance of cultivation technology. It is a fact, that Xanthomonas arboricola pv. jugladis highly infects hybrid walnut cultivars among humid weather conditions. However, growers acknowledge the higher yield of cultivars which are lateral bearers compared to traditional varieties and their almost similar fruit quality.

The rate of foreign walnut cultivars in Hungarian production is 27%. The reason of this high rate is that Hungarian nurseries could not always produce the required graft quantity.

9.8 New cultivars – Hungarian and foreign cultivars recommended for new plantations

In this section we present some promising walnuts among cultivars bred abroad, which can successfully be grown in Hungary on the base of their genetic background and suitable adaptation ability.

9.8.1 Ukrainian cultivars

Chernivetsky 1

Protogynous flowering (pistillate flowers bloom first), the blooming starts late, in May. Ripens in the second decade of September. The fruits are oval, with pointed apex, average sized, their weight is 11-13 g. Its shell is thin (0.9 mm), with an almost smooth surface, easy cracking. The kernel rate is 50-55%, light-coloured, tasty. Bears first fruit early, its fruits and leaves are resistant to walnut pathogens. The tree is moderately vigorous (Zatokovy 2009).

Our organoleptic tests with Ukrainian researchers concluded that the kernel of cultivar ‘Chernivetsky 1’ has outstanding characteristics. The jury scored the kernel of ‘Chernivetsky 1’ better than that of control variety ‘Milotai 10’.

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Fig 9.3 Chernivesky 1 (Photo: Zatokovy)

Bukovynsky 1

Protandrous flowering (staminate flowers bloom first). Its fruit size is average, the weight is 10-14 g, round, with pointed apex. Its shell is thin (0.8 mm), with an almost smooth surface, easy cracking. The kernel rate is 52.4% on average, light-coloured, easy cracking, tasty. Its yield and fruit quality is outstanding. The tree is moderately vigorous (Zatokovy 2009). Cultivar ‘Bukovynsky 1’ approaches the market value of ‘Milotai 10’ mainly as dried in-shell walnuts.

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Fig 9.4 Bukovynsky 1 (Photo: Zatokovy)

Klishkivsky

Protogynous flowering, the blooming starts late, in May. This variety ripens in mid-September. The green husk starts to crack at the apex, unlike that of other walnut cultivars. Its fruit is elongated, the size is average, the weight is 11–13 g. The shell thickness is 1.2 mm, its surface is smooth, yellowish brown, it approaches the market value of ‘Milotai 10’ as dried in-shell walnuts. The shell cracks easily. The kernel rate is 49-50%, light-coloured, tasty. The tree is vigorous (Zatokovy 2009).

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Fig 9.5 Klishkivsky (Photo: Zatokovy)

Grozynetsky

Protandrous flowering, the blooming begins at the beginning of May. The fruits ripen at the end of September. The fruits split laterally, they are large, have a trapezoid form and a weight of 14-15 g. Its shell is thin (0.9 mm), with a little striated surface, easy cracking. Its shell quality is similar to that of cultivar ‘Alsószentiváni 117’. The kernel rate is 49-53%, light-coloured, tasty. The tree is moderately vigorous (Zatokovy 2009).

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Fig 9.6 Grozynetsky (Photo: Bujdosó)

9.8.2 Slovenian walnut cultivars

Zdole-62

Late flowering cultivar. It is medium yielding but yields regularly. The fruit is a flattened trapezoid form, large-sized. Its fruit weight is 9.5-11 g, the kernel rate is 41-47%. The shell surface is moderately striated or smooth, light-coloured. The kernel colour is light, easy to clean. The tree is moderately vigorous, upright in habit. Highly susceptible to diseases (Solar and Stampar 2005).

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Fig 9.7 Candidate Zdole-62 (Photo: Bujdosó)

Erjavec

Protogynous flowering, the pistillate flowers bloom in mid-period. Its fruitfulness is good, some of the fruits develop from lateral buds, the yield is high and regular. The fruit is round, small or medium sized, with a weight of 8.6-10.2 g, the kernel rate is 49–54%. The shell surface is smooth, its colour is a transition between light brown and medium brown, the kernel is light-coloured, easy to clean. Its tree is highly vigorous, the crown is spreading. Highly susceptible to bacterial diseases (Solar and Stampar 2005).

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Fig 9.8 Erjavec (Photo: Bujdosó)

9.8.3 French cultivars

Franquette

Old French variety, which grounded the success of French walnut cultivation. Has a late leafing, but its shoots mature late as well, endangering the success of its cultivation. Protandrous flowering, the catkins bloom 10-12 days before pilstillate flowers. Ripens at the beginning-middle of October. The fruit weight is 10-12 g, elongated, the surface is slightly rough, light brown. The shell sutures close well. The kernel is a little elongated, light brown, its rate is 46%. The tree is moderately-highly vigorous (Verhaeghe 2011). There are no experiences at present regarding the Hungarian cultivation of ‘Franquette’.

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Fig 9.9 Franquette (Photo: Internet1)

Fernor

A new French cultivar, created by crossing ’Franquette’ and ’Lara’. It has a late leafing, bears first fruit early, most of its fruits are produced from lateral buds. Late-ripening, at the end of September - beginning of October. Its fruit is large, light-coloured, keeps its beautiful kernel colour for a long time, easy to clean, stores well. Has an outstanding taste. At maturity its yield can reach 4-5 t/ha dried in-shell fruits among French ecological conditions, and it is resistant to Xanthomonas there (Verhaeghe 2011). Until present we have good experiences with this cultivar among Hungarian ecological conditions. The kernel keeps its straw-colour for 9-12 months.

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Fig 9.10 Fernor (Photo: Internet 1)

9.8.4 Serbian cultivars

Sampion

Protandrous flowering. This is the most winter hardy cultivar, recommended for growing also among continental conditions. Its fruit is similar to that of ’Eszterházy I’, very nice, with an average weight of 14 g. The kernel is nicely light-coloured. The kernel rate is 58%. Moderately vigorous, high-yielding. Susceptible to Gnomonia. Its cold tolerance and winter hardiness is good according to Serbian data, it tolerates well the high fluctuations of temperature in winter (Internet 2, Cerovic et al 2010).

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Fig 9.11 Sampion (Photo: Internet 2)

Srem

High-yielding variety, its flowering is protandrous. The fruit is large, weighs 14-15 g. The shell is smooth-surfaced, thin, the kernel is light-coloured, pleasing. The kernel rate is 57%. It is resistant to major diseases of walnut. Has a moderate growth, the yield is average. Moderately - highly vigorous (Cerovic et al 2010., Internet 3).

GYUM ANGOL 9.12. ÁBRA

Fig 9.12 Srem (Photo: Internet 3)

Tisza

High-yielding, cluster type cultivar. The cluster can contain even 20 pilstillate flowers, but usually only 7-8 of them develops to maturity. Homogamous flowering can be observed in most years. Its fruit weighs 15 g, round, the kernel does not fill it completely. The kernel rate is 51% because of the thin shell. It can be recommended especially for habitats, where viticulture is efficient (Cerovic et al 2010., Internet 2).

GYUM ANGOL 9.13. ÁBRA

Fig 9.13 Tisza (Photo: Internet 4)

Bácska

Leafs together with cultivar Sheinovo, ends its vegetation period 10 days earlier. Protandrous flowering (staminate flowers bloom first). Moderately vigorous, high-yielding. Partly a lateral bearer. The fruit weighs 12 g, conic, light-coloured, with thin shell. The kernel is light-coloured. The kernel rate is 52%, its oil content is 68-70% (Cerovic et al 2010).

GYUM ANGOL 9.14. ÁBRA

Fig 9.14 Bácska (Photo: Internet 2)

9.8.5 Bulgarian cultivars

Sheinovo

This varietiy is a selected seedling with medium-early leafing. It shows a perfect dichogamy during flowering, the blooming is protogynous. Ripens in the 2nd or 3rd decade of September. 30-40% of its fruit ripen from lateral buds. The fruit is mid-large, weighs 12.5 g. The kernel colour is amber, the kernel rate is 54% (Figure 9.15.). The tree is highly vigorous. Shows a good resistance against Xanthomonas disease, but moderately susceptible to Gnomonia (Dzhuvinov et al 2010).

GYUM ANGOL 9.15. ÁBRA

Fig 9.15 Sheinovo (Photo: Gandev)

Silistrenski

This variety is a selected seedling having protandrous flowering. Ripens in the middle of September. Lateral bearer in 30-40%. The fruit is medium-sized, its weight is 11.5 g with a 51.5% kernel rate. The tree is moderately vigorous. Shows a good resistance against Xanthomonas disease, but moderately susceptible to Gnomonia (Dzhuvinov et al 2010).

GYUM ANGOL 9.16. ÁBRA

Fig 9.16 Silistrenski (Photo:Gandev)

9.8.6 American cultivars

Chandler

The most commonly cultivated hybrid walnut cultivar in the word. Its leafing is late in California, but medium-early in Hungary. Mostly a lateral bearer, but this is not typic in young trees. Ripens in the last decade of September. The fruits weigh 13 g, their diameter is 28-30 mm, smooth-surfaced, have a light shell and kernel colour. The kernel rate is 49%. The tree is moderately vigorous, partly upright in habit. Highly susceptible to Xanthomonas disease (Hendricks et al 1998). According to our experiences so far, this cultivar can successfully be grown in protected fruit sites in Hungary, high-yielding, but its fruit size is around 25 mm without irrigation.

GYUM ANGOL 9.17. ÁBRA

Fig 9.17 Chandler (source: Internet 3)

9.8.7 Walnut cultivars bred in Romania

Valrex

An early blooming cultivar (last decade of April), the flowering is protogynous. Ripens early (first decade of September). The fruits are oval, weigh 15.3 g on average, the shell is finely striated. The kernel rate is 51%, easy to crack and clean. The kernel is light-coloured, tastes very good. The tree is moderately vigorous, precocious, high-yielding. It is moderately susceptible to fungal and bacterial diseases of walnut. Has a very good winter hardiness. A terminal bearer only (Botu et al 2010/a, 2010/b, Cosmulescu 2010/a, 2010/b, 2012).

Jupâneşti

Its flowering time is mid-late (between 6-10 May), the flowering is protogynous. It ripens in the second decade of September. The fruit is elliptic, weighs 12,2 g on average, the shell is slightly striated. Its kernel rate is 49%, the nuts are easy to crack and clean. The kernel is very tasty, its colour is light amber (Figure 9.19.). Its tree is highly vigorous, bears first fruit late, but becomes high-yielding. It shows a good resistance against all walnut pathogens, its winter hardiness is good, a terminal bearer solely (Botu et al 2010/a, 2010/b, Cosmulescu 2010/a, 2010/b, 2012).

 GYUM ANGOL 9.18. ÁBRA  GYUM ANGOL 9.19. ÁBRA

Fig 9. 18 Valrex (Photo: Botu) Fig 9.19 Jupâneşti (Photo: Botu)

Valcor

Its flowering time is early (between 20-30 April in Romania), the pistillate flowers bloom in the medium period (between 1-5 May) in some years. Protandrous flowering. Its ripening time is mid-early, in the second decade of September. The fruit is wide oval, weighs 14.3 g on average, slightly striated. Its kernel rate is 52%, easy to crack and clean, the kernel is light-coloured. The tree is highly vigorous, bears first fruit early, high-yielding, moderately susceptible to bacterial and fungal diseases of walnut, has a very good winter hardiness. A terminal bearer solely (Botu et al 2010/a, 2010/b, Cosmulescu 2010/a, 2010/b, 2012).

 GYUM ANGOL 9.20. ÁBRA  GYUM ANGOL 9.21. ÁBRA

Fig 9.20. Valcor (Photo: Botu) Fig 9.21 Valmit (Photo: Botu)

Valmit

It has an early flowering (third decade of April in Romania), protogynous. Ripens in the second decade of September. The fruit is round, weighs 12.1 g on average, the shell surface is slightly striated. The kernel rate is 53%, easy to crack and clean. The kernel has an outstanding taste, light-coloured. The tree is highly vigorous, high-yielding, moderately susceptible to bacterial diseases, less susceptible to fungal diseases of walnut. Terminal bearer (Botu et al 2010/a, 2010/b, Cosmulescu 2010/a, 2010/b, 2012).

9.8.8 Hungarian walnut cultivars

Alsószentiváni 117

Its flowering is protogynous. It ripens in the 2nd decade of September. A terminal bearer solely. Its fruit is mid-large, 33-36 mm in diameter. The shell is slightly striated, semi-hard, light brown. Its kernel is yellowish brown, tastes good. The kernel rate is 48%. The tree is highly vigorous, with a little spreading canopy (Szentiványi 2006).

GYUM ANGOL 9.22. ÁBRA

Fig 9.22 Alsószentiváni 117 (Photo: Bujdosó)

Milotai 10

Its flowering is protogynous. Ripens in the 3rd decade of September. It develops 25% of its fruits on lateral buds. The fruit is regular spherical, 33-36 mm in diameter. Its shell is yellowish brown, there are markings or reticulations on the surface. The kernel is light yellow, tasty. The kernel rate is 47%. ’Milotai 10’ represents a standard market value regarding both in-shell and shelled walnuts. The tree is moderately vigorous, develops a hemisphere-shaped canopy (Szentiványi 2006).

GYUM ANGOL 9.23. ÁBRA

Fig 9.23 Milotai 10 (Photo: Bujdosó)

Tiszacsécsi 83

Its flowering is protogynous. It ripens at the end of September - beginning of October. Lateral bearer in 35%. Its fruit is mid-large, 32-34 mm in diameter, light brown with an ash-grey marking, the shell is a little striated, less pleasing. Its kernel is yellowish brown, tasty. The kernel rate is 48%. The tree is highly vigorous, develops a cylindrical canopy with a distinguished main branch (Szentiványi 2006).

GYUM ANGOL 9.24. ÁBRA

Fig 9.24 Tiszacsécsi 83 (Photo: Bujdosó)

Alsószentiváni kései

Protogynous flowering, has a very late budburst. Ripens at the beginning of October. Lateral bearer in 35%. The fruit is mid-large, 32-34 mm in diameter, elongated globose widening at the top, with a slightly striated surface. The kernel is light-coloured. The kernel rate is 48%. The tree is highly vigorous, develops an upright canopy with a a distinguished main branch (Szentiványi 2006).

GYUM ANGOL 9.25. ÁBRA

Fig 9.25 Alsószentiváni kései (Photo: Bujdosó)

Milotai kései

Protogynous flowering, has a very late budburst. Ripens in the first-second decade of October. Lateral bearer in 55%. The fruit is mid-large, 32-34 mm in diameter, round, has a smooth, slightly striated surface. The kernel is tasty, yellowish brown (Figure 9.26.). The kernel content is 45%. The tree is highly vigorous, develops a spreading canopy (Szentiványi 2006).

GYUM ANGOL 9.26. ÁBRA

Fig 9.26 Milotai kései (Photo: Bujdosó)

9.9 Walnut cultivars not recommended for cultivation in Hungary

The primary aspect in selecting foreign walnut cultivars is their suitable adaptability to Hungarian ecological conditions. On the base of this aspect, the vast majority of Turkish, Iranian and Californian cultivars bred under mediterranean climatic conditions can totally be excluded from Hungarian cultivation (except ’Pedro’ and ’Chandler’), as they do not have the suitable frost tolerance and winter hardiness.

Hungarian cultivation of a number of walnut cultivars bred in European countries is not possible as well, mainly because of their early leafing. This means, that we have to give up the cultivation of varieties leafing before 20th April. In addition, the Hungarian cultivation of varieties from chilly, humid, balanced mountain climatic conditions has to be avoided (cultivars from the former Checoslovakia), as these varieties produce a dark, unmarketable kernel quality under the arid climate of Hungary. Naturalization of cultivars showing a high susceptibility to walnut Xanthomonas disease has to be avoided as well, because their cultivation is expensive and their kernel quality highly depends on the year in all cases. In case of tolerant/resistant cultivars, we have to know the exact data of the pathogen (race) before beginning the adaptation experiments, against which the desired cultivar shows resistance. Ripening time is also a limiting factor. According to trends in cultivar use, it is not profitable to grow varieties that ripen after the middle of October, as fruit maturation is risky in this period and the market is saturated.

Chestnut ( Castanea sativa Mill.)

9.10 A brief history of chestnut breeding

The genus Castanea is native in Eurasia and in the Caucasus, its southern spreading reaches the 37th northern latitude, until the coasts of Tunisia, Syria and Lebanon in the northern hemisphere. Due to the conquests of the Greeks and Romans, the area of European chestnut ( Castanea sativa Mill.) widened from the Mediterranean coast to the Iberian Peninsula as well as to central and northern parts of Europe (Diamandis 2009).

In sites where natural chestnut population has a great genetic variability, first bred chestnut varieties were created by landscape selection. There are a number of Castanea population in the West-Causasian region of Russia, which constitute continuous forests. This high number of polpulations provides a genetic background to breeding work for forestry and horticulture (Pridnya et al. 2009).

In Hungary, chestnut breeding was carried out at the predecessors of the Research Institute for Fruitgrowing and Ornamentals Ltd., under the supervision of Péter Szentiványi, and as a result of this, the following cultivars were selected from Hungarian chestnut population: Kőszegszerdahelyi 29, Iharosberényi 2, Iharosberényi 29, Nagymarosi 22, Nagymarosi 37 and Nagymarosi 38. However, conscious variety usage started in the country only from the end of 1960’s, because the nursery technology of chestnut propagation was developed by that time (Szentiványi 1988). There is also a major chestnut population in Slovenia, where promising cultivars and genotypes were selected at the University of Ljubljana (Solar and Stampar 2009). A significant genetic diversity can be observed in China as well, therefore landscape selection is frequently used by chestnut breeders as a breeding method (Cheng and Huang 2009). In addition, landscape selection is carried out in Bulgaria (Bratanova-Doncheva et al. 2009) and in Albania (Lushaj and Tabaku 2009) as well.

Cross-breeding started in the last 2-3 decades at a lot of research stations, resulting mostly in the creation of interspecific hybrids. During cross-breeding, Castanea sativa Mill. x Castanea mollissima Blume (Chinese chestnut) or Castanea sativa Mill. x Castanea crenata Siebold & Zucc. (Japanese chestnut) combinations were used (Botu 2009). Interspecific hybrids from these combinations are still used in Brazil (Yamanishi et al. 2009). In the USA, breeding of interspecific hybrids is carried out between European and Chinese chestnuts, because Castanea dentata-t Borkh., which created the natural chestnut population, was almost totally destroyed by chestnut canker.

We have to mention a biotechnological method, by which Hozova et al. (2009) examine the diversity of the oldest natural chestnut population in the Czech Republic by microsatellite markers.

9.11 Major aims of breeding

Priority aims of chestnut breeding are: high yield, early and uniform maturation, as well as outstanding quality, which means large fruit size, globose fruit shape, dark colour, distinctive taste and low fat content. Important measures of value are the cleanability of kernel, its suitability for making a paste and its uniform texture (no hole inside the kernel). Beside fruit traits, another important feature is the uniform opening time of the green shell. The problem of self-fertility is a frequent topic in chestnut breeding teams (Soylu and Mert 2009, Serdar et al. 2009, Pandit et al. 2009, Solar and Stampar 2009). Marron type chestnut cultivars are prefered nowadays, these have only one big fruit in the cupule.

In addition, resistance against chestnut pests is highly important, and a priority breeding goal is to breed against Cryphonectria parasitica Murr. Barr. (syn.: Endotia parasitica), Phytophthora cambivora and Cytospora spp. Numerous countries involve genotypes from regional populations into resistance breeding (Soylu 2009, Celiker and Onogur 2009).

Anagnostakis et al. (2009) note the importance of resistance breeding against chestnut gall wasp (Dryocosmus kuriphilus). In the examined population there is presumably a monogenic dominant gene in the cytoplasm of genotypes not infected by the gall wasp. Sartor et al. (2009) in Italy examined the susceptibility of seven hybrid cultivars bred by crossing Castanea sativa × Castanea crenata to Dryocosmus kuriphilus, from which only variety ‘Bouche de Bétizac’ was not damaged by chestnut gall wasp.

For novel bred genotypes it is important that trees sould have a weak or moderate growth habit, an upright canopy habit with strong, almost vertical canopy elements for simlifying machine harvest (Soylu and Mert 2009).

From the aspects of cultivation technology, it is necessary to study the propagation possibilities of genotypes as well as their suitability for harvesting (Pandit et al. 2009).

The most effective “protection” against Criphonectria parasitica is to use hypovirulent strains (Criphonectria parasitica strains with weakened virulence). However, a constant examination and laboratory testing of hypovirulent strains is necessary, as not all hypovirulent strains are compatible with contaminating strains (Vidóczi et al 2007). At present, the collection of Hungarian chestnut hypovirulent strains can be found at the University of West Hungary, Faculty of Forestry. The survey of chestnut bark canker strains of Hungary, Slovakia, Ukraine and Romania is carried out at the University of Debrecen (Radócz et al. 2009). There are no perfect plant protection technology against chestnut canker in any of the chestnut producing countries of the world (Döken 2009). The CHV-1 hypovirulent strain is successfully used in Switzerland, as plant parts treated with this strain act well also after re-infections following the treatment (Heininger and Ringling 2009). In Italy, hypovirulent strains spreading naturally in larger chestnut populations can be the solution in the fight against Criphonectria parasitica. In Croatia, examination of four populations (Markuevac 1, Markuevac 2, Samobor, Sljeme) was carried out, in which six samples containing hypovirus were found (Krstin et al. 2009).

Trichoderma viride and Trichoderma harzianum are the base of biological protection against Phytophthora cambivora (Turchetti and Maresi 2009).

9.12 Genetic sources of breeding

European chestnut breeding is based on the species Castanea sativa (2n=24), the gene centre of European chestnut cultivation is in Turkey. The centers of Turkish chestnut cultivation are in Anatolia, in Marmara and Aegean regions, as well as near the Black Sea. Landscape selection is highly used in Turkey, and collected genotypes are applied in resistance breeding (Soylu 2009, Soylu and Mert 2009, Serdar et al. 2009). In addition, the creation of interspecific hybrids has a great importance as well, while Castanea sativa is a good gene source, but susceptible to Criphonectria parasitica. However, species Castanea mollissima Bl. (Chinese chestnut) and Castanea crenata Sieb. and Zucc. (Japanese chestnut) have resistance against this pathogene.

In China, Castanea henryi is also used in the breeding program to create Marron type varieties with moderate growth habit.

In the USA Castanea dentata is the native species. Unfortunately, natural population of Castanea dentata was almost totally destroyed by Criphonectria parasitica, therefore the chestnut assortment of the USA today builds mostly on interspecific hybrids of European and Japanese chestnuts (Fullbright et al. 2009).

In Slovakia, hybrids of Castanea sativa × Castanea crenata cross-breeding showed small differences against chestnut bark canker (Bolvansky et al. 2009).

In Japan, the breeding is based on Japanese chestnut (Castanea crenat). This chestnut species proves to be a good basis for breeding, as its fruits are larger that those of Castanea mollissima (Chinese chestnut). However, it is also true, that Japanese chestnut is harder to peel and clean compared to Chinese chestnut (Takada et al. 2009).

9.13 Breeding programs and cultivar use of major chestnut producing countries

In China, the most important chestnut producing country of the world, the province Miyun is the largest area of chestnut cultivation, more than 50% of Chinese production is produced here. Chinese chestnut assortment is based on the species Castanea mollissima. At present 300 chestnut cultivars are cultivated in 22 provinces of the country.

In Turkey, almost all chestnut producing areas developed their own cultivar assortment. In the centre of the Black Sea region, cultivars Ersinop, Ural, Erfelek, Eryayla and Serdar are the most common. Outside this region, cultivars Haciömer, Sariaslama and Alimolla are also popular.

In Italy, ‘Marrone di Castel del Rio’ and ‘Marrone di Marradi’ with the highest mineral content and the lowest fat content, as well as ‘Marrone di Valle Castellana’ with the highest sugar content are the most popular among Marron type cultivars. The cultivar Marrone del Mugello, which has a protected geographical indication (PGI) by the European Union, is still spreading, while its chestnut flour represents a unique quality. A unique cultivar assortment was developed in many of the country’s chestnut producing areas.

In the USA, all of novel bred cultivars are interspecific hybrids, such as ’Colossal’ (Castanea sativa × Castanea crenata), and ’Eaton’ ( Castanea mollissima × Castanea crenata). The Chinese cultivar ’Ever-Fresh’ is also popular.

In Spain, chestnut is not only a fruit species cultivated for its fruit and tree, but a part of Spanish landscape and heritage. Beside ‘Castaña de Galicia’, which has a protected geographical indication (PGI), cultivars Famosa, Negral, Longal, Garrida and Parede play an important role in Spanish chestnut cultivation as well.

In French chestnut cultivation, beside bred cultivars of Castanea sativa (Comballe, Bouche Rouge, Montagne, Sardonne) we can also find interspecific cultivars (Bouche de Bétizac, Marigoule), which are less susceptible to chestnut canker and chestnut Phytophthora disease. ‘Bouche de Bétizac’ is a popular cultivar especially in Southwest France, the use of other interspecific cultivars (such as Bournette, Précoce migoule) is not preferred there.

In Romania, chestnut breeding was performed formerly at the Fruit Research Station of Baia Mare, then in Valcea, at present it is carried out at the University of Craiova. As a result, 7 cultivars certified by the state was bred by landscape selection (Mara, Iza, Gureni, Hobita, Polovragi, Tismana, Prigorie). In addition, a number of promising genotypes is under evaluation: VL 503 H, VL 504 H, VL 530 B, VL 602, VL 603, VL 604. Romanian cultivars / genotypes with the highest fruit yield are the following: Marigoule CA 15, Marissard CA 122, Bournette CA 112, VL 503 H, VL 530 B, Marsol CA 07.

In Portugal, the Castanea sativa cultivar ‘Judia’ is the most popular and most exported chestnut variety.

In Slovenia 10 chestnut genotypes were developed: ’Kozjak-1’ cultivar originates from Stajerska region, ’MP-23’, ’Avbar’ and ’Martin’ genotypes from Dolenjska region, ’Suhor(A)06’, ’S-15/b’ and ’S-248’ genotypes from Bela Krajina region, while ’Loza’, ’L-voda’ and ’L-Frelih’ genotypes from Vipavska dolina region.

In India, also genotypes developed by landscape selection are used in chestnut cultivation, as there is a very rich genetic diversity in Kashmir Valley. Outside India, genotypes made by regional selection are popular in Lebanon and Syria as well.

In Slovakia, open pollinated seedlings are evaluated on the base of mainly forestry aspects (eg. trunk height).

In Japan, chestnut breeding is carried out in the National Institute of Fruit Tree Science, where a whole cultivar series was developed using species Castanea crenata. Promising new Japanese cultivars are Porotan (fruit weight: 26—30 g), Ishizuchi, Riheiguri, Tanzawa and Tsukuba.

In Albania, the largest chestnut population can be found in Tropoja province, which is the basis of regional selection.

9.14. Chestnut cultivar use in Hungary

According to the 2001 data of the Hungarian Central Statistical Office (KSH), there are a total of 467 hectares of chestnut plantations in Hungary. We cultivate other cultivars, not present in the Hungarian National Variety List, in greater quantities. The “other” designation probably means seedlings or, in a smaller rate, foreign cultivars. Among cultivars present in the National Variety List, bred in Hungary, we cultivate mainly Kőszegszerdahelyi 29 (cultivation proportion 36,2%). The cultivation proportions of other cultivars are the following: Iharosberényi 29 (7,1%), Iharosberényi 2 (6,7%), Nagymarosi 22 (4%), Nagymarosi 37 and Nagymarosi 38 (2,2 – 2,2%).

9.15 . New cultivars – cultivars recommended for new plantations

Iharosberényi 2

This cultivar ripens at the end of September, beginning of October. High-yielding, bears fruits on 52% of its shoots, with an average of 2,2 fruits per cupule. The fruits are very large, 37-38 mm in diameter, covered by a strong dark brown pericarp. Its processed kernel is light brown (Szentiványi 1998).

GYUM ANGOL 9.27. ÁBRA

Fig 9. 27 Iharosberényi 2 (Photo: Bujdosó)

Nagymarosi 38

Ripens at the beginning of October. High-yielding and bears first fruit early, on 52% of its shoots, with an average of 1.6 fruits per cupule. The fruit is large, 37-38 mm in diameter, the pericarp surface is shiny, striped by dark brown, which increases its marketability, and has a relatively high spot. Its fine-textured, thin skin is easy to peel. The kernel taste is harmonic, light yellow when processed (Szentiványi 1998).

GYUM ANGOL 9.28. ÁBRA

Fig 9.28 Nagymarosi 38 (Photo: Bujdosó)

Kőszegszerdahelyi 29

Ripens at the middle of October. Regularly and high-yielding cultivar, 80% of shoots bears fruit. Its cupules contain 1.6 fruits on average. The fruits are medium or large, 36-37 mm in diameter, the yellowish brown skin is easy to peel. The kernel is sweetish, yellowish brown when processed (Szentiványi 1998).

GYUM ANGOL 9.29. ÁBRA

Fig 9.29 Kőszegszerdahelyi 29 (Photo: Bujdosó)

Marrone di Marradi

Its fruits are very large, medium brown, striped, with shiny surface. The reason of its popularity is not only its large fruit size and high kernel content, but its outstanding versatility in food industry as well (Internet1).

GYUM ANGOL 9.30. ÁBRA

Fig 9.30 Marrone di Marradi (source: Internet1)

Marrone di Castel del Rio

This cultivar with protected geographical indication (PGI) was selected from Santero Valley. Its fruit size is very large, the skin is dark brown, striped. The kernel is excellently sweet, can be processed in many ways (Internet2).

GYUM ANGOL 9.31. ÁBRA

Fig 9.31 Marrone di Castel del Rio (source: Internet2)

Kozjak-1

It was selected in the valley of Drava, in the slopes of Kozjak (Slovenia). It has the largest fruit size among Slovenian cultivars. The average fruit weight is 16.4 g (61 fruits/kg). Its fruit is wide oval, dark brown, longitudinally sriped. The spot is long and wide. The fruit contains always one embryo (Solar and Stampar 2009).

Avbar (syn.: MP-30)

A cultivar bred in Slovenia by regional selection. The fruit is medium-sized, its weight is 13.7 g (73 fruits/kg). The fruit is round or elliptic, with a wide and large spot. Fruit colour is reddish or dark brown, nicely sriped (Solar and Stampar 2009).

L-voda

A cultivar bred in Slovenia by regional selection. Its fruit is large, weighs 15.3 g on average (65.3 fruits/kg). The fruit is wide elliptic, with a wide and large spot. Fruit skin is reddish, not sriped (Solar and Stampar 2009).

9.16 Cultivars not recommended for cultivation in Hungary

Varieties, that are not recommended for Hungarian cultivation are of Mediterranean origin, therefore their growing is unsafe under Hungarian ecological conditions because of their winter hardiness (Table 9.1).

Tabl 9.1

Cultivar name:

Colossal

Bouche de Bétizac

Marron de Lyon

Advantageous characteristics of the cultivar

bears first fruit early, high-yielding, large fruit size

early maturation, large fruit size, good storability

medium-large fruit size, good storability

Disadvantageous characteristics of the cultivar

low winter hardiness, susceptible to chestnut bark canker

fruit yield and quality are highly determined by the habitat

bears first fruit late, low winter hardiness

 

Hazelnut ( Corylus avellana L.)

9.17 A brief history of hazelnut breeding

The common hazelnut (Corylus avellana L.), which is cultivated in Hungary, is native in Central-Europe, the Balkan Peninsula, Western and Eastern Asia and North America (Tomcsányi 1979). In spite of this, we cultivate it only in a small territory, in protected micro-areas in Hungary. Hungarian hazelnut growers can cultivate only those varieties, which can tolerate the long dormancy period and have a late flowering time.

First bred hazelnut cultivars were seedlings, later they were followed by cultivars bred by landscape selection, then by cross-breeding. Cross-breeding is very popular in the USA, Italy, France and Romania. In addition, a high rate of naturalization can be observed in all hazelnut producing countries. At present, the increasing use of Italian and American cultivars is typical.

A hazelnut breeding program was carried out at the predecessors of the National Research Institute for Horticultire, when Péter Szentiványi created the cultivar ‘Bőtermő nagy’ by landscape selection. As a result of regional selection, ‘Bőtermő nagy’ adapts well to Hungarian ecological conditions, therefore this cultivar has significantly spread in Hungary (KSH 2003). Beside ‘Bőtermő nagy’, the cultivar ‘Nagy tarka zelli K. 5’, selected at the University of Horticulture and Food Industry, has a role in Hungarian cultivation as well. This is a genotype of a foreign variety of unknown origin, selected in Hungary.

Beside cultivars bred in Hungary, almost all important world varieties can be found in our hazelnut variety assortment. However, we cultivate clone varieties of all world cultivars, selected among Hungarian ecological conditions (Cosford K.2, Roman hazelnut K. 1, Grosse aus Trient K. 3, Bollwilleri csoda K.4, Princess Royal K. 6). In many cases it is difficult to identify the origin of cultivars, as natural hybrids are often created between cultivared varieties.

Hazelnut cultivation is spreading in the world more and more, which is proven by the fact, that there were 24 significant hazelnut producing countries in 1997, while in 2009 this number was 30, according to FAO database. In spite of the increasing number of hazelnut producing countries, this fruit species is still grown among mediterranean climatic conditions, 80% of the world’s total production comes from Turkey and Italy (Fidigelli and Salvador 2009). In countries located north of the Mediterranean, hazelnut can be counted as a fruit species which can be cultivated with risk. However, the spreading of hazelnut plantations can be promoted by the active interest for summer truffle (Tuber aestivum Vittadini), as hazelnut is a good host plant for this species.

9.18 Major aims of breeding

One of the key breeding aims for hazelnut is yield reliability all around the world, and in connection to this, late flowering. The flowers of hazelnut bloom the earliest among cultivated fruit species, therefore late flowering is especially important in Central Europe as well.

High yield is also important, as according to some Ukrainian researchers, promising cultivars have to reach a yield of 8 kg per bush at maturity.

As regards maturation, the primary aim is early maturation, so that growers could rapidly enter into the market with the fresh product.

Outstanding fruit quality is very important. Among different hazelnut fruit shapes, round or globose are preferred because of their excellent fruit size. In addition, light colour, thin shell, good taste and a kernel content of at least 43-50% are still important. Heterogenous fruit quality makes a problem by a number of certified hazelnut cultivars.

Good winter hardiness is essential for a good hazelnut cultivar, representing the key element of cultivation success in a lot of habitats. Drought tolerance also comes into view as a breeding aim.

As regards sprouts, weak sprout formation is advantageous, because this way we can protect the plants against Phytoptus avellanae more effectively (Slyusarchuk and Ryabokon 2005, Rovira et al 2005, Fidigelli and Salvador 2009).

9.19 Genetic sources of breeding

In Europe we cultivate solely the species Corylus avellana (2n=22) (Thompson et al. 1996). In Ukraine, the species Corylus heterophylla Fisch. ex Trautv was also involved in breeding work in order to increase winter hardiness (Slyusarchuk and Ryabokon 2005). In Georgia, breeding and cultivation is both based on species Corylus pontica and Corylus conchica (Mirotadze 2005).

In Chinese hazelnut breeding, Corylus heteropylla and Corylus avellana combinations are used, as Corylus heteropylla has a good winter hardiness and frost tolerance, but it is low-yielding and has small fruits (below 1 g). However, yielding capacity and fruit quality of Corylus avellana is outstanding. A number of interspecific hybrids have derived from the crossing of these two species, some of which can already be found in cultivation (Xie et al 2005).

American researchers at the Oregon State University performed resistance breeding against pathogen fungus Anisogramma anomala (Peck) E. Müller, and as a result, they created the cultivar Santiam (McCluskey et al 2009). Resistance breeding is carried out also at the eastern coast of USA, at the University of New Jersey, where varieties ‘Zimmerman’ and the Spanish bred ‘Ratoli’ are used for resistance, as both cultivars inherit well their resistance (Molnar et al 2009).

Pilloti et al. (2009) create resistant genotypes against pathogenes by biotechnological methods. Their research is based on identifying resistant genes (R genes), as well as on studying molecular background related to pathogenes.

9.20 Breeding programs and cultivar use of major hazelnut producing countries

The largest hazelnut producer and exporter of the world is Turkey, where reforms have been carried out in hazelnut cultivation with the help of World Bank. The program’s main element was, that plantations in flat areas were replaced, and financial independence and administrative autonomy was given to the Union of Hazelnut Sales Cooperatives. As a result of the measures, Turkish hazelnut cultivation became significantly stronger. In the western basin of the Mediterranean Sea, Turkish varieties ‘Tombul’, ‘Palaz’, ‘Kalınkara’, ‘Çakıldak’ and ‘Sivri’ are popular.

Italy has its own hazelnut breeding, therefore they cultivate a lot of cultivars bred in Italy: Tonda delle Langhe, Tonda Gentile Romana, Tonda Rossa, Tonda Bianca, Tonda di Giffoni, Montebello, Avellana Speciale, Riccia di Talanico, Giromelo, Mortarella, Tonda Romana, Tonda Gentile delle Langhe, Comune di Sicilia. The Italian variety assortment is the richest in European hazelnut production.

In the USA, hazelnut breeding is carried out at the Oregon State University, the high-yielding cultivar Willamette was created there. In addition, other varieties bred in America (Barcelona, Royal and Ennis) have a high proportion in the hazelnut cultivation of the USA. At present, growers in the US State Oregon are trying to involve some cultivars resistant to the pathogene Anisogramma anomala (Santiam, Yanhill) into cultivation.

In Spain there is a significant hazelnut breeding, and as a result, a high number of hazelnut cultivars were created. Spanish hazelnut breeding, which started mostly with the selection of the population in Asturia, continues by the collaboration of IRTA and SERIDA research institutes. Researchers selected 10 genotypes (Aciera-1, San Pedro-4, Rubiano-3, Pola de Allande-3, Riocastiello-2, Yerbo-2, Los Cuetos-1, Las Cuevas-1, Las Cuevas-2 and Tanda-1), their comparative evaluation is still continuing.

As Spanish ecological conditions are almost the same as those in the US State California, Spanish growers can reliably naturalize the cultivars bred in California. The reason of this is that the American variety ‘Negret’ is popular on the Iberian Peninsula.

In Iran, research work related to hazelnut is carried out at Kamal-Abad Horticultural Research Station. Genotypes bred in Iran have a very diverse genetic background. The cultivar ‘Dobooseh’ stands out, because its dendrogram differs from that of other Iranian genotypes and has a number of specific alleles.

In Georgia, hazelnut cultivation has a great tradition. Cultivars bred and produced in the country are highly demanded in European markets (early varieties: Dedoflis titi, Tskhenis dzudzu, Saivanobо, Chkhikvictava, medium varieties: Gulshishvela, Nemsa, Vanis tetra, Vanis tsiteli, Anakliuri, Uchа-tkhili, Kharistvala, Ata-baba, late varieties: Khachapura, Gile, Shveliskura, Gandja, Cherkezuli).

In China, hazelnut cultivation began in the 19th century by importing Italian and American varieties. These varieties adapted well in Shandoung, Anhui and Hebei provinces. Chinese hazelnut breeding started as well, and as a result, cultivars ’Lianfeng’ (2.71 g fruit weight, 45% kernel content), ’Yifeng’ and ’Taifeng’ (3.21 g fruit weight, 46% kernel content) were created. All varieties have a yield of 2.1 kg/bush in the 8th year (dried fruit with pericarp).

Among interspecifc hybrids, 5 cultivars were selected by chinese researchers (Pingdinghuang, Bokehong, Dawei, Jinling, Yuzhui), but they have a smaller fruit weight (2.0-2.66 g) and kernel content (40-46%) compared to varieties bred traditionally.

In Romania, our eastern neighbour, hazelnut breeding is still carried on in Oltenia region, situated in the Carpathian Mountains. Research work started at the Fruit Research Station of Valcea, where ‘Valcea 22’, ‘Cozia’ and ‘Uriaes de Valcea’ cultivars, suitable for dessert hazelnuts, as well as ’Romavel’ was bred, which is suitable for both dessert and food industrial purposes. All cultivars bred there adapt perfectly to ecological conditions of Oltania region (South Carpathians). The most promising among novel bred cultivars seems to be ‘Uriaes de Valcea’, as it fulfils all breeding requirements: late flowering, early ripening - beginning of September, large fruit size, 4.8 g on average, round shape, thin skin, 49% kernel content. It can be propagated by grafting only. A newly bred variety recommended for outstanding hazelnut habitats is ‘Arutela’, which ripens early, at the end of August, high-yielding (2.8-3 t/ha dried yield with pericarp), its fruit is small, rounded.

In Ukraine, hazelnut breeding dates back to 1930’s. In the first period, the primary aim of breeding in the Ukrainian Research Institute of Forestry and Forest Melioration was to create genotypes which are high-yielding and suitable for planting as undergrowth in forests and to steppe. In the 1950’s, this breeding goal was replaced by aims of fruit growing, where primary aspects were yield safety and fruit quality. Since 1981, there are 12 hazelnut cultivars on the Ukrainian National Variety List (’Bolgradszka novynka’, ‘Borovszkyi’, ‘Dar Pavlenka’, ‘Klynovydnyi’, ‘Koronchatyi’, ‘Lozivszkyi sharovydnyi’, ‘Pyrizhok’, ‘Raketnyi’, ‘Sriblyastyi’, ‘Stepovyi 83’, ‘Shedevr’, ‘Shokoladnyi’).

In Serbia, hazelnut cultivation is based mostly on Italian, Turkish and English varieties. Cultivation was grounded by adaptation experiments in the country, therefore a unique variety assortment could develop in all regions.

In Australia, as a result of hazelnut breeding, cultivars ‘Tokolyi/Brownfield Cosford’ (syn.: ’TBC’) and ‘Tonollo’ were created. Naturally, beside these two varieties, others can also be found in Australian cultivation, such as Italian ’Tonda di Giffoni’, American ’Barcelona’, ’Ennis’, ’Butler’ and Spanish ’Segorbe’. The cultivar ‘Whiteheart’ with its outstanding kernel features is the result of the breeding work carried out in New Zealand.

Chilean hazelnut cultivation is based on Italian, Spanish and American varieties (Barcelona, Tonda Romana, Gironell, Tonda delle Langhe, Grifoll, Morell and Negret).

In France, almost the whole of hazelnut production (2 500 ha) is owned by the UNICIQUE company, and 250-300 ha hazelnut plantation can be found in Corsica.

In Portugal, breeding work started in 1980 by the selection of hazelnut population located in the northern part of the country. At present they cultivate Spanish (Segorbe, L. de Espagne, Daviana), American (Butler) and English (Daviana) varieties.

In the Netherlands, the basis of hazelnut cultivation is the fact, that hazelnut is native in this country as well. ‘Emoa 1’, ‘Emoa 2’ and ‘Emoa 3’ are the three varieties bred in the Netherlands, which are high-yielding, have an excellent market value and show low susceptibility to main pathogenes damaging hazelnut, therefore they are suitable for ecological production. There is a plantation in the country, where hazelnut, walnut and sea-buckthorn were planted together.

In Croatia, cultivars ‘Istarski duguljasti’ and ‘Istarski okruglasti’ were created as a result of the breeding work. Beside these two cultivars, a number of Italian (Camponica, Noccione, Tonda di Giffoni, Tonda Romana), French (Merveille de Bollwiller, Fertile de Coutard), Spanish (Negret) and English (Cosford) cultivars can be found as well in Croatian hazelnut growing.

In Slovenia, naturalized cultivars are grown, among which Italian cultivars (Noccione, Tonda di Giffoni, Tonda Romana) and candidates dominate (104E, 1040F, 101, 123 F). Beside Italian cultivars, ‘Barcelona’, ‘Brixnut’, ‘Butler’, ‘Ennis’ and ‘Germ’, bred at the Oregon State University, as well as the Spanish ‘Negret’ and the Croatian ‘Istrski duguljasti’ and ’Istarski okruglasti’ can also be found in Slovenian hazelnut cultivation.

In Albania, mainly Italian cultivars are used (Tonda Romana, Tonda Gentile delle Langhe, Tonda di Giffoni, San Giovanna), but ’Visoka’ bred at the Fruit Tree Research Institute of Vlora is also cultivated.

9.21 Cultivate use of hazelnut in Hungary

In Hungary, one fourth of the hazelnut producing plantations are from cultivar ‘Római mogyoró K1’ (Roman hazelnut), which is closely followed by ’Bőtermő nagy’ bred in Hungary (cultivation rate 21.8%), ’Cosford K.2’ (cultivation rate 18.5%) and ’Merveille de Bollwiller K.4’ (cultivation rate 14.45%). We have to note, that the proportion of other hazelnut cultivars is high, almost 20% in Hungarian hazelnut cultivation (Hungarian Statistical Office – KSH 2003).

9.22 New cultivars – Hungarian and foreign cultivars recommended for new plantations

In this section we present some promising hazelnuts among cultivars bred abroad, which can successfully be grown in Hungary on the base of their genetic background and suitable adaptation ability. Naturally, we also mention the most promising hazelnut cultivars bred in Hungary.

Római mogyoró K.1 (Roman hazelnut)

A variation of an old Italian cultivar selected in Hungary. Ripens at the end of August – beginning of September. It usually yields its fruits in pairs. Its acorn is large, rounder or a little flattened, 23 mm in width and 19 mm in length. The acorn shell is thick, light brown. The bush is vigorous, wide conic in shape, highly sprouting (Apostol and Szentiványi 1998).

GYUM ANGOL 9.32. ÁBRA

Fig 9. 32 Római mogyoró K.1 (Roman hazelnut) (Photo: Fidigelli)

Cosford K.2

It was selected in Hungary, its name is the same as that of ‘Cosford’, but it is not a variation of that. Ripens in the first part of September. The fruits are mostly in pairs, the acorn is large, 20 mm in width, fells out easily from the cupule at maturation. The acorn shell is thick, dark brown, striped. The kernel content is 45%. The bush is vigorous, elongated conic in shape, seems like a bush-shaped tree (Apostol and Szentiványi 1998).

GYUM ANGOL 9.33. ÁBRA

Fig 9.33. Cosford K.2 (Photo: Szentiványi)

Barcelona

Old American hazelnut cultivar with high adaptability, very popular in Western Europe. Blooms in middle period, ripens medium late. Its cupule is longer by one third than the fruit. The fruit is large, medium or dark brown, rounded, with medium thick fruit shell and a kernel content of 39-42%, tastes well. High-yielding. Highly vigorous, has a large shrub (Solar 2000, Internet 1).

GYUM ANGOL 9.34. ÁBRA

Fig 9.34 Barcelona (Source: Internet1)

Istarski duguljasti

A cultivar bred and highly cultivated in Croatia. High-yielding. Its fruits are tubular, large, tasty. The bush has a medium growth and upright habit. Strong sprouting (Miljkovic 2000).

GYUM ANGOL 9.35. ÁBRA

Fig 9.35 Istarski duguljasti (Internet2)

Istarski okruglasti

Bred on Istria, can only be cultivated in areas with good ecological conditions. Blooms and yields in the middle period, medium-high yielding. The fruits are round, large, tasty, with 45% kernel content. Its bush is vigorous, with semi-upright habit. Sprouts weakly (Miljkovic 2000).

GYUM ANGOL 9.36. ÁBRA

9.36 Istarski okruglasti (Internet3)

Tonda Gentile Romana

A cultivar bred in Italy. Its female flowers bloom in middle or late period, the few male flower in middle period. Medium ripening. The fruit extends beyond the cupule. Its fruit is round, medium large, light brown. The kernel is round, medium large, uniform, tasty. The kernel content is 57%. The bush is semi upright, of weak growth habit, moderately sprouting (Internet4).

GYUM ANGOL 9.37. ÁBRA

9.37 Tonda Gentile Romana (Internet4)

9.23 Hazelnut cultivars not recommended for cultivation in Hungary

Cultivars that are not recommended for Hungarian cultivation are of Mediterranean origin, therefore their growing is unsafe under Hungarian ecological conditions because of their winter hardiness and early blooming (Table 9.2).

Table 9.2. Hazelnut cultivars whose growing is unsafe under Hungarian climatic conditions

Cultivar name

Longue d’Espange

Negret

Tonda di Giffoni

Palaz

Origin

Spain

Spain

Italy

Turkey

Advantageous characteristics

late flowering, outstanding market value

high-yielding, good fruit quality

medium or high-yielding, stable yield

outstanding fruit size and quality

Disadvantageous characteristics

its winter hardiness is suitable only under submediterranean climatic conditions

low winter hardiness, highly sprouting, non-uniform maturation

very late blooming of male and female flowers

its winter hardiness is suitable only under mediterranean climatic conditions

(Source: Internet5)

Control questions:

Walnut:

1. Describe the history of Hungarian walnut breeding!

2. What are the major aims of walnut breeding?

3. What are the most important genetic sources of walnut?

4. What breeding methods can be used in walnut breeding?

5. What are the dangers and international experiences of naturalization?

6. What is the significance of intespecific hybrids?

7. What are the major cultivar trends in the important walnut producing countries of the world?

8. What are the trends of breeding and cultivation use in the major European walnut producing countries?

9. What are the criteria of an ideal walnut cultivar?

10. What are the most important characterictics of the Hungarian walnut population, that can be used in breeding?

11. Describe the major characteristics of Hungarian walnut cultivars!

12. Describe the Ukrainian walnut cultivars and their most important characteristics!

13. Describe the Slovenian walnut cultivars and their most important characteristics!

14. Describe the French walnut cultivars and their most important characteristics!

15. Describe the Serbian walnut cultivars and their most important characteristics!

16. Describe the Bulgarian and the American walnut cultivars and their most important characteristics!

17. Describe the Romanian walnut cultivars and their most important characteristics!

18. On the base of what aspects can we exclude a foreign walnut cultivar from the Hungarian cultivation?

Chestnut

1. Which breeding methods can be used for creating chestnut cultivars? Evaluate the success of each breading methods!

2. Which breeding methods were used in Hungarian chestnut breeding?

3. Which chestnut species can be used in chestnut breeding? Evaluate them!

4. Which breeding aims should be considered in chestnut breeding?

5. Describe the cultivar trends of the most significant chestnut producing countries.

6. Describe the Hungarian chestnut cultivar use.

7. Which are the most famous chestnut cultivars bred in Hungary?

8. Describe and evaluate with their most important pomological features those chestnut cultivars, which have been bred abroad, but can be promising as potential cultivars in Hungarian ecological conditions.

9. What is the first obstacle for the naturalization of chestnut cultivars in the territory of Hungary?

Hazelnut

1. Describe the brief history of hazelnut cultivation.

2. What are the major aims of hazelnut breeding?

3. What genetic sources do researchers use in hazelnut breeding?

4. What are the major hazelnut producing countries?

5. What are the most popular cultivars in the major hazelnut growing countries?

6. What are the major cultivar trends in hazelnut cultivation?

7. Describe the Hungarian hazelnut cultivar use.

8. Specify and briefly describe the major hazelnut cultivars bred in Hungary.

9. What are the most promising foreign and Hungarian hazelnut cultivars?

10. Why can’t we cultivate a number of foreign varieties in Hungary?

Literature:

Walnut

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  24. McGranahan, G.H., and Leslie, C.A. (2004).‘Robert Livermore’, a Persian walnut cultivar with a red seedcoat. HortScience 39:1772.

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Online sources:

Internet1: http://www.walnuttrees.co.uk/shop/walnut-fruit-trees/fernor

Internet2: http://www.coopenoix.com/enus/lacoop%c3%a9rative/lesproduits/noixfra%c3%aeches.aspx (as of 28th July 2012)

Internet3: http://sacramentopacking.com/uploads/Chandler_Walnuts.JPG (as of 3rd September 2012)

Chestnut

  1. Anagnostakis, S., Clark, S., McNab, H. (2009): Preliminary report on the segregation of resistance in chestnuts to infestation by oriental chestnut gall wasp. Acta Hortic. 815:33-36.

  2. Bolvanský, M., Kobza, M., Juhásová, G., Adamčíková, K., Ostrovský, R. (2009): Spread of chestnut blight in a plantation of young Castanea sativa and Castanea hybrids. Acta Hortic. 815:261-270.

  3. Botu, M. (2009): Sweet chestnut situation in Romania. Acta Hortic. 866:511-515.

  4. Bratanova-Doncheva, S., Chipev, N., Dimitrova, V. (2009): Origin, state and perspective of chestnut cultivation in Bulgaria. Acta Hortic. 866:517-525.

  5. Çeliker, N.M. and Onoğur, E. (2009): Preliminary studies on the fungal disorders especially on ink disease causing decline of chestnut trees in Turkey. Acta Hortic. 815:227-232.

  6. Cheng, L.L., Huang, W.G. (2009): Diversity of choroplast DNA SSRs in wild and cultivated C. mollissima: Evidence of cultivated C. mollissima origon. Acta Hortic. 866:243-249.

  7. Diamandis, S. (2009): Sweet chestnut: from the „Kastania” of the ancient Greeks to modern days. Acta Hortic. 866:527-530.

  8. Döken, M.T. (2009): Chestnut blight and a review of the related studies in Turkey. Acta Hortic. 815:213-220.

  9. Fullbright, D.W., Mandujano, M., Stadt, S. (2009): Chestnut production in Michigan. Acta Hortic. 866:531-537.

  10. Heiniger, U. and Rigling, D. (2009): Application of the Cryphonectria hypovirus (CHV-1) to control the chestnut blight, experience from Switzerland. Acta Hortic. 815:233-246.

  11. Hozova, L., Jankovsky, L., Akkak, A., Torello Marioni, D., Botta, R. and Šmerda, J. (2009): Preliminary study of the genetic structure of a chestnut population in the Czech Rebulic based on SSR analysis. Acta Hortic. 815:43-50.

  12. Krstin, LJ., Krajačić, M., Ćurković Perica, M., Novak-Agbaba, S. and Rigling, D. (2009): Hypovirus-infected strains of the fungus Cryphonactria parasitica in the Central part of Croatia. Acta Hortic. 815:283-288

  13. KSH (2003): Gyümölcsültetvény-gazdálkodás Magyarországon (Fruit plantation management in Hungary), 2001. Adatgyűjtemény, 1. kötet. 64-67. p.

  14. Lushaj, B.M., Tabaku, V. (2009): Conersion of old, abandoned chestnut forest into simple coppice and from simple coppice forest into Orchards in Tropoja, Albania. Acta Hortic. 866:251-258.

  15. Pandit, A.H., Kour, A., Wani, M.S. and Mir, M.A. (2009): Genetic resources of chestnuts in Kashmir Valley. Acta Hortic. 815:51-56.

  16. Pridnya, M.V., Pinkovsky, M.D., Romashin, A.D. (2009): Novelty position of European Chestnut forests in Russia (Western Caucasus) and perspective of their protection and sustainable development. Acta Hortic. 866:543-550.

  17. Radócz L., Tarcali G., Egyed K. (2009): The chestnut blight fungus (Cryphonectria parasitica Murr, (Barr) in the Central-European region. Acta Hortic. 866:399-404.

  18. Sartor, C., Botta, R., Mellano, M.G., Beccaro, G.L., Bounous, G., Torello Marinoni, D., Quacchia, A. and Alma, A. (2009): Evaluation of susceptibility to Dryocosmus kuriphilus yasumatsu (Hymenoptera: Cynipidae) in Castanea sativa Miller and in hybrid cultivars. Acta Hortic. 815:289-298.

  19. Serdar, U., Demirsoy, H. and Demirsoy, L. (2009): Determination of superior chestnut genotypes in the Central Black sea region of Turkey. Acta Hortic. 815:37-42.

  20. Solar, A., Stampar, F. (2009): Promising chestnut genotypes from Slovenia. Acta Hortic. 866:259-264.

  21. Soylu, A. (2009): The development of chestnut industry of Turkey in the last half century. Acta Hortic. 866:505-510.

  22. Soylu, A. and Mert, C. (2009): The future of chestnut breeding work in Turkey. Acta Hortic. 815:27-32.

  23. Szentiványi P. (1998): Dió (Walnut) In: Soltész M. (szerk.): Gyümölcsfajta-ismeret és –használat. Mezőgazda Kiadó, Budapest. 343-346. p.

  24. Takada, N., Sato, A., Sawamura, Y., Nishio, S., Saito, T. (2009): Influence of pollen on pellicle removability and nut weight of Japanese chestnut (Castanea crenata Sieb. et Zucc.) ’Porotam’. Acta Hortic. 866:239-242.

  25. Turchetti, T. and Maresi, G. (2009): Biological control of chestnut diseases in Italy: Effectiveness of blight and ink disease management. Acta Hortic. 815:253-260.

  26. Vidóczi H., Varga M. Szabó I. (2007): Chestnut blight and its biological control in the Sopron Hills, Hungary. Acta Silvatica & Lignaria Hungarica. 3: 199-205.p

  27. Yamanashi, O.K., Sobierajki, G.R., Bueno, S.C.S., and Pommer, C.V. (2009): Chestnut in Brazil: Reseraches and perspectives. Acta Hortic. 866:539-541.

Online sources:

Internet1: http://www.flickriver.com/photos/pruffoli/5095873899/

Internet2: http://www.marronedicasteldelrio.it/marroni_igp.htm

Hazelnut

Literature:

  1. Apostol J., Szentiványi P. (1998): Mogyoró (Hazelnut). In Soltész M. (szerk.): Gyümölcsfajta-ismeret és –használat. Mezőgazda Kiadó, Budapest. 347-351. p.

  2. Fidigelli, C., de Salvador, F.R. (2009): World hazelnut situtation and perspectives. Acta Hortic. 845. 39-52. p.

  3. KSH, (2003): Gyümölcsültetvény-gazdálkodás Magyarországon (Fruit plantation management in Hungary), 2001. Adatgyűjtemény, 1. kötet. 68-71. p.

  4. McCluskey, R.L., Mehlenbacher, S.A., Smith, D.C., Azarenko, A. N. (2009): Advanced selection and new cultivar performance in hazelnut trials planted in 1998 and 2000 at Oregon State University. Acta Hortic. 845. 67-72. p

  5. Miljkovic, I (2000): Croatia. Hazelnut cultivar list and some important characteristics and remaks. In. Köksal, Y. (szerk.): Inventory of hazelnut research, germplasm and references. REU Technical Series No. 56. Food and Agricultural Office of the United Nations ROME, Mediterranean Agronimic Institute of Zaragosa, Spain. http://www.fao.org/docrep/003/X4484E/x4484e11.htm#P4777_40180

  6. Mirotadze, N. (2005): Hazelnut in Georgia. Acta Hortic 686, 29-34. p.

  7. Molnar, T.J, Capik, J.M., Gorrreda, J.C. (2009): Response of hazelnut progenies from known resistant parents to Anisogramma anomala in New Yersey, USA. Acta Hortic. 845, 73-82. p.

  8. Pilotti, M., Brunetti, A., Tizzani, L., Gallelli, A., Lumia, V., Gervasi, F. (2009): gene candidates for pathogen perception in Corlyus avellana. Acta Hortic. 845. 115-122. p.

  9. Rovira, M., Ferreira, J.J., Tous, J., Ciordia, M. (2005): Hazelnut diversity in Asturias (Northern Spain). Acta Hortic. 686, 41-46. p.

  10. Solar, A (2000): Slovenia. Hazelnut cultivar list and some important characteristics and remaks. In. Köksal, Y. (szerk.): Inventory of hazelnut research, germplasm and references. REU Technical Series No. 56. Food and Agricultural Office of the United Nations ROME, Mediterranean Agronimic Institute of Zaragosa, Spain. http://www.fao.org/docrep/003/X4484E/x4484e11.htm#P4777_40180

  11. Slyusarchuk, V.E., Ryabokon, A.P. (2005): Ukrainian hazelnuts: Cultivars, agrotechnics, perspectives. Acta Hortic 686, 603-608. p.

  12. Thompson, M.M, Lagerstedt, H.B, Mehlenbacher, S. A (1996): Hazelnuts. In: Janick, J., Moore, J.N. (szerk.): Fruit breeding, vol. 3, Nuts. Wiley, New York, 125–184 p.

  13. Tomcsányi P. (1979):Gyümölcsfajtáink. Gyakorlati pomológia (Our fruit cultivars. Pomology in practice). Mezőgazda Kiadó, Budapest.

  14. Xie, M., Zheng, J., Radicati, L., Me., G. (2005): Interspecific hibridization of hazelnut and performance of 5 varieties of China. Acta Hortic 686, 65-70. p.

Online sources:

Internet1: http://hazelnut.org.nz/variety/Barcelona.html (2013. január 17.)

Internet2: http://www.njuskalo.hr/orasasti-plodovi-sjemenke/ljesnjaci-istarski-duguljasti-ljusci-1-kilogram-26-kn-oglas-5896055 (2013 . január 17.)

Internet3: http://www.agroportal.hr/agro-baza/sortne-liste/voce/ljesnjak/istarski-okrugli/ (2013. január 20.)

Internet4: http://safenut.casaccia.enea.it/db/accessions/1175 (2013. január 20.)

Internet5: http://safenut.casaccia.enea.it (2013. január 20.)

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A projekt célja magyar és angol nyelvű digitális tananyagok fejlesztése a Budapesti Corvinus Egyetem Kertészettudományi Karának hét tanszékén. Az összesen 14 tananyag (hét magyar, hét angol) a kertészmérnök Msc szak és a multiple degree képzés keretében kerül felhasználásra. A digitális tartalmak az Egyetem e-learning keretrendszerével kompatibilis formában készülnek el.

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A projekt célja magyar és angol nyelvű digitális tananyagok fejlesztése a Budapesti Corvinus Egyetem Kertészettudományi Karának hét tanszékén. Az összesen 14 tananyag (hét magyar, hét angol) a kertészmérnök Msc szak és a multiple degree képzés keretében kerül felhasználásra. A digitális tartalmak az Egyetem e-learning keretrendszerével kompatibilis formában készülnek el.

A tananyagok az Új Széchenyi Terv Társadalmi Megújulás Operatív Program támogatásával készülnek.

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A pályázat felidejére elkészültek a lektorált tananyagok, amelyek feltöltése folyamatban van. 

 

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Utolsó frissítés: 2014 11. 13.