Pear breeding trends and aims in the world. Promising cultivars

 
Author: Magdolna Tóth
 
2.1. A brief history of pear cultivation and breeding
 
Pears were developed in the Caucasus, in the area between Black Sea and Caspian Sea. They were involved in cultivation in Asia at least 3000 years ago, then Indo-European tribes brought them to Europe. First written records originate from Greece from 1000 BC. Homer referred to pears as the gift of the Gods, later Theophrastus (371-287 BC) wrote about Greek pear cultivation, including propagation by grafting and cutting. Cato (235-150 BC) reports about cultivation techniques which are used even today. The Roman Plinius (23-79) describes at least 35 cultivated varieties. At the end of Sung dynasty (China, 1279 AD) there were already more than 100 varieties.
In the Middle Ages, pears were widely cultivated in Western and Central Europe. According to Cordus (1515-1544), the fruits of these varieties resembled in many ways to present cultivars, but their fruit flesh was not melting and soft enough. In the beginning of the 1800’s, more than 900 varieties were already cultivated in France. In this century, cultivation and breeding moved to Belgium. The first famous breeders were Hardenpont, P. N. and van Mons, J. B. In England, cultivation began in the 1200’s, but breeding started a lot later. ‘Williams’ was discovered in 1796, and ‘Conference’ was selected in the 19th century. At the beginning, cultivars were formed by accidental hybridization of two species (P. communis and P. nivalis). Knight was the first to perform a controlled crossing around 1800 in England, then Mendel started the conscious hybridization in the second half of the 19th century in Bohemia.
Domestication of Asian pear started about 3300 years ago, and first market plantations were established more than 2000 years ago in China. However, Chinese breeding started only in 1956. In Japan, cultivation started in the 8th century, but larger plantations were established at the end of the 19th century. The breeding program still running today started in 1915.
Pears (P. communis) were carried by French and English settlers to North America, and the first plantation was established in 1629. Asian pear (P. pyrifolia) was domesticated more lately, in the 1800’s by Chinese immigrants. The cultivar ‘Kieffer’, which is resistant to fire blight became popular among the first varieties deriving from the first crossings between the two species (1873). The first winter hardy, but not quite good quality and highly fire blight susceptible varieties got to South America from Russia in 1879. Essentially, pear breeding started in South-America, Australia, New Zealand and Africa only recently.
The beginning of the Hungarian cultivar research can be dated to the 17th century. János Lippai describes more pear varieties, such as Muskotály pear, Kármán pear, Makaria pear. Hungarian pomologists, like Máté Bereczki, Ferenc Entz and Dezső Angyal contributed highly to the prosperity of domestic pear cultivation.
The world’s pear yield is constituted by two main pear species (groups) and fruit types. Pyrus communis (L.) (European pear, common pear) is cultivated in countries of Europe, North and South America, Africa and Australia. Asian or Japanese pear (called nashi abroad), whose main species is Pyrus pyrifolia (Burm) Nakai, is cultivated throughout South and Central China, as well as Japan and South-East Asia since ancient times. However, there is almost no interest for European pears in Asia. An exception to this is Northern Japan, where there are problems with the winter hardiness of Asian pears.
Pear is the second most significant fruit species after apple among temperate zone fruits. The world’s pear yield was around 23 million tons per year in recent years. More than 70% of the yield is produced in Asia, about 15% in Europe, thus Asian pear is dominant in the world’s yield. 1.8 million tons of pear is harvested on the Southern Hemisphere, and the majority of this is marketed on the Northern Hemisphere. Europe’s leading pear growing country is Italy, where the yield is around 7-800 thousand tons per year. In Hungary the yearly pear yield is highly fluctuating, in recent years it was around 12-50 thousand tons.
 
2.2. Evolution biology, gene sources
 
The genus Pyrus belongs to Rosaceae family, Pomoideae subfamily, and comprises 24 species, which - according to the opinion of researchers - originate from a mutual ancestor developed in Western mountains of China. The first taxa spread from this area in Eastern and Western directions. The species complex of the cultivated pear Pyrus communis L. is constituted by cultural derivatives of species P. pyraster Burgsd. and P. nivalis Jacq. Figure 2.1. shows the spreading of species believed to play a role in the development of European pear cultivars, in Europe and Asia Minor.
 
 
2.1
 
Figure 2.1.: Spreading of Pyrus species in Europe and Asia Minor.
 
Species can be classified according to the centers of ancient habitats of main pear species. Figure 2.2. shows the spreading of species which played a role in the development of Asian pear cultivars.
 
 
 
2.2
 
Figure 2.2.: Spreading of Pyrus species in Eastern Asia.
 
Most of pear varieties are diploid (2n = 34). There are some triploid (3n = 51) cultivars (‘Diel’s butter pear’, ‘Pap körte’), and we can find tetraploids as well (4n = 68) among new cultivars (e.g. ‘Super Conference’, ’Dayali’).
 
2.3. Breeding methods
 
Breeders use the following methods in creating and introducing new pear cultivars:
Selection of seedlings of known or unknown origin.
The majority of cultivated pear varieties was developed as a random seedling, only the female parent is known in most cases. Some varieties are several hundreds of years old and still have an important role in cultivar use, e.g. ‘Williams’ (1796), ‘Bosc’ (1800), ‘Passe Crassane’ (1845).
Cross-breeding.
From the end of the 19th century until present, hybridization is carried out in major pear cultivating countries (Italy, France, USA, Canada, Russia).
Crossings between species are usually used for creating resistant pear cultivars. At the Canadian Harrow Institute, less susceptible or resistant cultivars to Erwinia amylovora were created using species P. ussurienis, P. pyrifolia and P. calleryana (e.g. ‘Harrow Delight’, ‘Harwest Queen’). Similar resistance breeding is carried out in the USA, Italy and France.
In crossings between varieties, ‘Williams’ and ‘Doyenné du Comice’ are used more frequently. As progenies of ‘Williams’, ‘Packham’s Triumph’ (‘Williams’ x ‘Angevin Beauty’) and ‘Highland’ (‘Williams’ x ‘Doyenne du Comice’) can be mentioned. Because of this, there is a high risk for impoverishment of genetic bases. Recently, attempts are made for crossing Asian and European pear cultivars in order to create special varieties e.g. in New Zealand. ‘Crispie’ and ‘Maxie’ are among the first successful varieties.
Mutation.
Spontaneous mutation of pear cultivars is not as frequent as by apple, only muntants of some main varieties are known which are different in one-two traits. In alteration of fruit skin colour, mutants with bronze or red cover colour can be formed. ‘Williams’ has more red mutants, e.g.: ‘Red Williams’ (Max Red Bartlett), but there is a russeted mutant as well (‘Russett Bartlett’). Red mutant of ‘Clapp’s favourite’ is ‘Red Clapp’ (Starkrimson). Habit can also be altered. A less vigorous mutant (spur type) can be found e.g. by cultivar ‘Trévoux’, this is called ‘Supertrevoux’. ‘Williams’ has a mutant which ripens at a different time (‘Eller Bartlett’).
At least four European and five Asian pear cultivars were bred by induced mutation. In the first case flowering time, flower colour, ripening time, fuit colour and growth habit could be modified. In Italy, less vigorous variants of basic varieties were created in 1990 (‘Abate Light’ and ‘Conference Light’), which proved to be resistant to Erwinia amylovora. In Asian pear, disease resistance and self-fertility could be reached by induced mutation. The most successful of these is ‘Gold Nijisseiki’, which is resistant against black spot, and replaced the highly susceptible basic variety (‘Nijisseiki’).
Clonal selection. It is not significant in case of pear. During viral decontaminations, variants better in one-two characteristics were found in case of some old standard cultivars (‘Williams’, ‘Conference’), and these are propagated instead of the basic cultivars.
Biotechnological methods in the service of breeding. A lot of markers were succeded to develop, with whom diversity examinations were carried out first inside Pyrus genus. In addition, several linkage groups were already mapped. There is a possibility for markering the gene of scab resistance, and at least four QTLs, determining fire blight resistance had been able to identify. Transgenic lines were produced at varieties ‘Passe Crassane’, ‘Conference’ and ‘Doyenné du Comice’.
 
2.4. Major aims of breeding
 
Genus Pyrus is quite diversified genetically, and has a considerable variability in morphology and physical adaptation as well (Figure 2.3.). The aim of breeders is to utilize this variability for breeding new cultivars, which could deserve the satisfaction of both consumers and growers by their increasing quality, attractive look and adaptation to ecological conditions.
 
2.3
 
Figure 2.3.: Diversity of Pyrus species (Source: Hancock and Lobos 2008)
 
Quality means different values in case of European and Asian cultivars. The main advantage of the first group is their pleasant taste and flavour combined with a soft and melting flesh, and they must be free from stone cells. The main virtue of Asian pears is their crunchiness and sweet taste, and a moderate fiber content is preferred. Pear fruit, beside its suitability for fresh consumption, can be used for processing as well. It is very popular for example as dried fruits, can produce half or whole compotes, it is indispensable for fruit coctails and for baby food, and it is an outstanding raw material for many alcoholic products (pálinka, perry). The aim of up-to-date breeding is to guarantee a quality suitable for different utilization targets and to improve this quality.
The needs for the fruit look (skin colour, size, shape) can vary between regions and time periods. In European pears, yellow skin colour and regular shape (as known from ‘Williams’) are ideal, but rusty surface is preferred, too. The blushed colour became first popular as a result of the South-African breeding started in the 90’s, and the breeding of red skin pears was launched in America. Today’s trendy fruit types are shown in the following pictures (Figure 2.4.).
   
 
2.4
 
Figure 2.4.: Pear cultivars with different colour and shape for widening the assortment (Photo: Józsefné Göndör, Krisztina Honty, József Racskó)
 
In case of Asian pear, the requirement is a larger size (at least 10 cm in diameter) and a regular round shape. The surface can be light green, shiny and smooth, as well as yellow or light brown covered with a uniform russet (Figure 2.5.). Fruit quality of old varieties is poor, the fruit flesh is hard and gritty (that is why it is called sand pear), therefore an important aim is to improve the quality. Cultivars in the pictures and those recommended for Hungarian cultivation are already have a good flesh quality.
  
 
2.5
 
Figure 2.5.: Fruit types of Asian pear (Photo: Józsefné Göndör and Krisztina Honty)
 
In North-America (USA, Canada), breeders focused earlier and better on resistance against different diseases and on winter hardiness than in Europe. However, the rapid spread of fire blight stimulates European breeders (major breeding countries: France, Germany, Italy, Romania) as well to place resistance among their primary breeding aims. Because of increasing losses by Asian pear, focusing on resistance is likewise inevitable. In addition, suitability of given climatic conditions became a part of general breeding aims. An intensive pear breeding is carried out on the Southern Hemisphere as well (New Zealand, Southern Africa, Brazil). Especially, they breed fresh consumption cultivars that fulfil the consumer needs of the Northern Hemisphere. The importance of the suitability for machine harvest is increasing, which make claims on fruit and tree.
The most important breeding aims can be summarized as follows:
– increasing the climatic adaptability, frost and drought tolerance,
– resistance breeding against the most dangerous diseases of European pear [Erwinia amylovora (fire blight), Venturia pirina (scab)],
– resistance breeding against the most dangerous diseases of Asian pear [Alternaria alternata (black spot disease), Venturia nashicola (nashi scab), Gymnosporangium asiaticum (pear rust)],
– tolerance to pests [Cacopsylla pyricola (pear Psylla) and Eriosoma pyricola (pear root aphid)],
– decreasing growth habit,
– improving fruit quality,
– achieving self-fertility, increasing the tendency to parthenocarpy,
– widening the ripening period,
– improving fruitfulness,
– suitability for machine harvest,
– improving storability and suitability for processing.
 
2.5. The international status of cultivar use
 
Pear variety use is quite conservative due to the fidelity of consumers to well-known cultivars. Until the end of the 20th century, only old, sometimes more hundred years old varieties were planted all over the world, only their red-coloured variants were added to the assortment. That is, in spite of the high number of pear cultivars, only 8-10 varieties are cultivated in market plantations around the world. Europe’s most cultivated varieties are ‘Conference’, ‘Williams’ (which is a leading cultivar under the name Bartlett in the USA), ’Abate Fetel’ and ’Doyenné du Comice’. These four varieties give almost 60% of the yield. For example in Belgium the rate of ’Conference’ in market plantations is 87%. The world’s most popular cultivars have an elongated pear shape (like ‘Abate Fetel’ or ‘Conference’) or red skin. In Hungary, mainly ‘Bosc’ is cultivated, which ripens in autumn but can be stored well, and ‘Williams’ is also popular. These two cultivars together give more than half of Hungarian yield.
 
 
2.6. A  Abate Fetel
A
 
 
2.6. B Red Sens
B
 
 
 
2.6 C
C
 
 
2.6. D Conference
D
 
Figure 2.6.: Today’s most popular pear cultivars of the world: A – ‘Abate Fetel’, B – ‘Red Sensation’, C – ‘Red Williams’, D - ‘Conference’
 
However, in the last decade there is a significant interest for new and still unknown cultivars in Europe and America. Mainly disease (fire blight, scab) or pest (Psylla) resistant cultivars, as well as cultivars with novelty fruits (e.g. honey pear: ‘Seckel’, coctail pear with 20-30 mm in diameter: ‘Red Face’, pear with conspicuous lenticels: ‘Forelle’) are popular. Beside this, a good example for renewing the variety use and widening the assortment can be experienced in Portugal, where the local cultivar ‘Rocha’ was planted in large plantations, and the yield is marketed not only in Europe but exported to overseas as well (Figure 2.7.).
 
  

2.7. A kép  Rocha gyümölcs

Fruit of 'Rocha' pear after storage at the end of May

2.7.B kép  Rocha befőtt

Product processed from 'Rocha' pear

Figure 2.7.: The only pear market cultivar of Portugal, on which the production development program was based. (Photo: Magdolna Tóth)

 
2.7. Cultivars recommended for trying or for planting in plantations
 
2.7.1. Fire blight resistant pear cultivars
The breeding of fire blight (Erwinia amylovora Burr.) resistant pear cultivars is carried on for nearly a hundred years in the USA and Canada. The literature on this topic is quite rich. Cultivars are distributed by significant European nurseries.
Harrow Delight
It was created in Canada in the Harrow Institute. (‘Williams’ x (‘Early Sweet’ x ‘Old Home’). Ripens 10 days before ‘Williams’, at the beginning of August, can be stored for 1-2 months. Its fruit is medium large (180-210g), with a conic pear shape, resembles highly to ‘Williams’. Its taste is very good, the flesh texture is outstanding. The skin ground colour is yellowish green, washed by red on the sunny side. The tree is moderately vigorous, with slightly upright branches, suitable for intensive crown forms. Develops well also on quince. Has an early onset, high-yielding. Its recommended pollinators are: ‘Williams’, ‘Bosc’. Proved to be resistant against fire blight in Hungary as well, according to examinations of both flowers and shoots. Resistant against scab.
 
 
2.8
 
Fig 2.8. Harrow Delight
 
 
Harrow Sweet (HW 609)
It was bred in Canada as the hybrid of ‘Old Home’ x ‘Early Sweet’ progeny and ‘Williams’. Ripens 30 days after ‘Williams’, in the middle-end of August, can be stored for 3–4 months. Its fruit is medium large (170-200g), with a conic pear shape. The skin ground colour is yellowish green, washed by red on the sunny side, with clearly visible lenticels. The flesh has a good consistence, sweet, keeps its good quality after storage as well. The tree is moderately vigorous, with slightly upright branches, suitable for intensive crown forms. Quince compatible. Has an early onset, very high-yielding, sometimes requires thinning, as it has a tendency to alternancy. According to French data, its cumulated yield exceeded that of ‘Williams’. Its recommended pollinators are: ‘Williams’, ‘Abate Fetel’. Proved to be resistant against fire blight in Hungary as well.
 
2.9
 
Fig 2. 9. Harrow Sweet
 
Harvest Queen
It was bred in Canada by crossing Michigan 572 x ‘Williams’. Can be harvested one week before ‘Williams’. Tends to fruit drop before ripening. Its fruit is medium large, resembles to ‘Williams’, but rarely becomes gritty. Has a regular pear shape, the skin is shiny. The flesh is butter-like, sweet. Its moderately vigorous tree is quince compatible. Its flowering time is early, mid-early. Its pollinators are: ‘Harrow Delight’, ‘Beurre d’Anjou’ (incompatible to ‘Williams’). Has an early onset, yields regularly. Resistant against fire blight.
 
 
 
 
2.10
 
Figure 2.10.: Harvest Queen (Source: http://www.omafra.gov.on.ca)
 
Moonglow
It was bred in the USA, one of the first cultivars of resistance breeding, which is the result of a complex crossing [(‘Williams’ x ‘Seckel’) x ‘Williams’] x ‘König Karl Württenberg’].
Can be harvested 1 week after ‘Williams’, has a good taste. Flavours develop better after 2 months of storage on 0.5 ºC. The fruit has an almost regular pear shape, resembles to ‘Williams’ but chunkier. The fruit is medium large (150-200g), smaller than that of basic the variety, and its taste is poorer. However, the fruit can be well tansported. The tree is of weak growth habit, develops a small and quite loose crown. Blooms in middle period, the flowers are small. Has an early onset and a good fruitfulness. Demanding for ecological conditions. The cultivar’s biggest value is its high resistance against fire blight, which was also proved by our in vitro shoot examinations on the Department.
Beside these cultivars, we can also recommend the following varieties which have a good fire blight resistance according to in vitro tests of the breeding countries: ‘Bohemica’ bred in the Czech Republic, ‘Boheme’ and ‘Aida’ bred in Italy, ‘Magness’ and ‘Harovit Sundown’ (HV 614) bred in America and ‘UTA’ bred in Dresden-Pillnitz.
 
 
2.11. abra Moonglow
 
Fig 11. Moonglow
 
 
2.7.2. Red skin pear cultivars
The first red skin pear cultivars were formed by mutation, the others were created by crossing. Fruit coloration, as well as its extension and deepness depends also on the habitat. These fruits can be well marketed even today, but according to European growing experiences, they are more demanding, therefore can be cultivated with a higher cost. The colour stability of ‘Red Williams’, which was the first to discover, proved to be poor, so only its hybrids are recommended for cultivation (e.g. ‘Red Sensation’). Red skin varieties are cultivated mostly in America, but the following varieties are distributed by European nurseries as well.
 
Lombacad (Cascade)
It was created in Oregon (USA) by crossing ‘Red Williams’ (Max Red Bartlett) x ‘Doyenné du Comice. According to literature data, it has to be harvested in the middle of September for long storage, it can be stored well for 6-8 months. Its fruit is mid-large or large, cylinder shaped, 60-80% of the surface is dark red with lighter lenticels. Its smooth skin is thin and moderately susceptible to branch rubbing. The flesh is white, slightly gritty, melting sweet-acidic. The tree is vigorous, but can be grown on quince, it has an early onset, high-yielding. Develops fruits on short and medium long shoots, therefore requires annual pruning. Blooms late, it good pollinators are ‘Bosc’, ‘Doyenné du Comice’ and ‘Williams’.
 
 
2.12
 
Figure 2.12.: Fruit of Lombacad (Cascade) (Photo: Józsefné Göndör)
 
Red Clapp (Synonym: Starkrimson)
Bud mutation of ‘Clapp’s favourite’ (USA). It can be planted in Hungary since 1979, but it is cultivated only on a small surface. It can be harvested some days after ‘Clapp’s favourite’, in the second week of August. Can be stored only for a short time, becomes overripe fast, softens easily. Its fruit is medium or large, with regular pear shape. The skin is smooth, its entire surface is bright red. Skin colour is stable. The fruit flesh is yellowish white, melting, sweet-acidic. Its tree is slightly more vigorous than moderate (but less vigorous than ‘Clapp’s favourite’). Has a mid-late onset, yields moderately but regularly. Its pollinators are: ‘Beurré d’Hardenpont’, ‘Bosc’, ‘Conference’. Its ecological needs are the same as those of the basic cultivar.
 
 
2.13
 
Figure 2.13.: Fruit of Red Clapp (Starkrimson) (Photo: Józsefné Göndör)
 
 
Red Sensation
It was created by clonal selection in Australia in 1980, from ‘Sensation’ found near 1940 as a bud mutation of ‘Red Williams’. Can be harvested a couple of days after ‘Williams’, can be stored well for 4-5 months. Its fruit has a regular pear shape, the pedicel is short or medium long. On the yellow ground colour it is first spotted by red, then becomes bright red until maturity. Its flesh is cream or white, juicy, soft, melts pleasantly in the mouth, sweeter than ‘Williams’. Its scent and flavour is the same as by ‘Williams’. Looks great also in fruit salads sliced together with its red skin. The tree is similar to that of ‘Williams’. There is no experience about it in Hungary. Its best pollinators are: ‘Starking’ and ‘Moonglow’. Its ecological needs are similar to those of the basic cultivar.
 
 
2.14.abra Red Sens tál
 
Figure 2.14.: Fruit of Red Sensation (Photo: Krisztina Honty)
 
 
2.7.3. Other promising pear cultivars
Concorde
It was created in England (East Malling) by crossing ‘Doyenné du Comice’ x ‘Conference’. Distributed in Europe since 1990. Its optimal harvest time, mid-September falls between the harvest times of the two parent varieties. It is easy to transport and manipulate, can be stored until April in controlled atmosphere. The fruit is mid-large or large, has a very elongated pear shape. Fruit skin is smooth, straw-coloured when ripe, the surface is russet-free. Its fruit quality is better than that of ‘Conference’, can be a substitute because of its higher fruitfulness. It is moderattely vigorous, develops a little smaller crown than ‘Conference’. Suitable for intensive crown forms on quince rootstock. Has an early onset, its fruitfulness was 20% better than ‘Conference’. Its relative yield can be even higher because of its smaller crown. Does not tend to alternancy as much as ‘Conference’. Its ecological and plant protection needs are similar to those of ‘Conference’.
 
 
2.15
 
Figure 2.15.: Fruit of Concorde
 
 
Eldorado
It was selected as a random seedling from a hedgerow in the USA. It ripens in the middle-end of September. As a high value, it can be stored longer than ‘Williams’ (for 6-7 months). The fruit size is mid-large or large, with a conic shape, resembles very much to ‘Williams’. Its taste is very good, the flesh texture is outstanding, less gritty. Outstanding for processing as well. The tree is moderately vigorous, with slightly upright branches. Has an early onset, high-yielding. Proved to be susceptible to fire blight in Hungary.
 
 
2.16.abra  Eldorado
 
Figure 2.16.: Fruit of Eldorado (Photo: Józsefné Göndör)
 
 
2.7.4. Japanese pear - nashi
Among the numerous names used in international literature (e.g. water pear, Asian pear, apple pear, pear apple, etc.), Japanese pear and “nashi” became accepted in Hungarian literature.
Fruit characteristics.
Beside other fruit characteristics, nashi differs from European pear in its ripening type as well. These fruits ripen on the tree, post-storage ripening is not required for consumption. The optimal harvest time is hard to determine exactly, measurement of coloration and soluble dry matter content is recommended. According to Hungarian experiences, at least 2-3 picking phases are needed.
Their fruits have mostly apple shape (e.g. ‘Kosui’, ‘Hosui’), but ‘Yakumo’ has a wide elliptic, while ‘Imamura Aki’ an elongated egg shape. The skin colour extend from yellowish green to bronze (see pictures in breeding aims chapter). Lenticels are clearly visible on fruits, the skin surface can be smooth (mainly by light skin cultivars) or rough (‘Kosui’). Growers prefer cultivars with a bronze-like tone for planting, because light-coloured skin is highly sensitive at handling, browns easily.
Fruit weight can reach 200-450 g or more after thinning in the original habitat (Japan), while in Italy it is reported to be around 250 g. In Japan, fruit quality requirements are rather high (a diameter over 100 mm and a regular round shape). It is produced almost always by protecting each fruit from bird damage using a sac.
Fruits of Asian pears are firm, yet crunchy and juicy (85.8% water content). They contain less energy (167 kJ/100 g) than apples (around 209 kJ/100 g) and pears (234 kJ/100 g). However, their cellulose, hemicellulose and pectin content is high (3%) which is beneficial from nutritional aspects. The fruit flesh is white, whitish yellow, sweet, some cultivars have a special spicy flavour. Their consumption is recommended after cooling and they are good for some kind of indigestions.
Ecological needs.
Ecological needs of nashi are similar to those of European pear. It requires 16°C average temperature in the vegetation period. Its annual mean temperature requirement is 10 °C. It can be damaged during spring frosts because of its early flowering. Annual precipitation is 1500-2000 mm in its original habitat, but according to European experiences, the water demand of nashi is not higher than that of European pear. A forced ripening can begin in the period of fruit maturation because of low air moisture content, or underdeveloped fruits can be formed. Therefore it is important to ensure an irrigation possibility for increasing the plantation’s moisture content. Some cultivars, especially those with light coloured skin, are susceptible to wind damage.
Growth characteristics.
Most of Japanese pear cultivars are moderately or highly vigorous. Fruiting shoots and laterals are fragile, so pruning the crown must be done with care. Therefore it is cultivated in Japan using pergolas with a strong support system, which bears early and high yields and frequent windstorms. Fruits develop mostly on 2-3 year-old fruiting spurs, but some cultivars produce fruit on 60-80 cm shoots as well. Not only apical buds, but the lateral buds of fruiting shoots can be mixed buds. As rootstocks for nashi, seedlings of Pyrus pyrifolia, Pyrus communis, Pyrus calleriana, Pyrus betulaefolia can be used, and it is propagated on OHF hybrids in Italy lately. Nashi cultivars are incompatible to quince rootstocks.
Phenological features.
There are differences also in phenological features. Flowers bloom some days before European cultivars. Cultivar ‘Shinko’ which is the earliest in flowering, blooms 10-12 days before ‘Williams’ pear. The harvest period lasts from end July until October. Similarly to pear cultivars, nashi varieties require cross-pollination, therefore 2 or 3 cultivars has to be planted together. In Japan, most cultivars are hand thinned because of oversetting, this is the only way to reach the adequate size. We list the possible pollinators of the known cultivars according to literature data.
Cultivar descriptions
We highlight mostly those varieties, which are already popular in Europe, and which are successfully cultivated in Italy and France.
Hosui
Hybrid of a ‘Kikusui’ x ‘Yakumo’ progeny and ‘Yakumo’. One of the main cultivars of Japan, and this is the most popular cultivar in Europe. In Hungary it was certified by the state. Ripens in the medium period, can be harvested in the third-fourth week of August. The fruit is mid-large (150-200 g), with a medium thick skin, its colour is uniformly golden-bronze, covered by pleasant big lenticels. The fruit flesh is crunchy, juicy, a little acidic, sometimes gritty. Can be stored for 2-3 months. The tree is highly vigorous, develops an upright crown. It bears fruit on young, 2-3-year-old fruiting spurs, so older fruiting laterals have to be regenerated. It has an early onset, yields well. It has an early blooming, good pollinators are ‘Shinko’ and ‘Shinseiki’. Resistant against black spot (Alternaria alternata (Fr.) Keissler).
 
 
2.17.abra Hosui
 
Figure 2.17.: Hosui (Photo: Józsefné Göndör)
 
 
Kosui
It was created by crossing ‘Kikusui’ and ‘Wazekoso’ in Japan, where this is the variety cultivated in the highest proportion. Ripens in the mid-early period, the first harvest is in the first week of August. It has to be harvested in at least two phases. The fruit is mid-large (150 g). The skin is a little rough, golden brown, can be rusty on almost 50% of the surface, the lenticels are highly conspicuous. The fruit flesh is cream-coloured, firm, sometimes gritty around ovary, has a high sugar content. It can crack near sepals in some years. Fruit thinning is important in order to get a larger fruit size. The tree is highly vigorous. It bears fruits mostly on 2-year-old fruiting spurs, on the external parts of the crown. Has a very early onset, but is fruitfulness is moderate. The flowering time is late, its good pollinator is ‘Shinseiki’. Resistant against black spot (Alternaria alternata (Fr.) Keissler).
 
 
2.18
 
Figure 2.18.: Kosui (Photo: Józsefné Göndör)
 
 
Shinko
Hybrid of ‘Nijisseiki’ x ‘Amanokava’ (Japan). It can be harvested late, in mid-late September. The fruit is medium or large (200-250 g). The flesh is white, crunchy, sweet, sometimes with stone cells around the ovary. Can be stored well for 5-6 months. In France its virus-free clones are propagated, and as a late ripening cultivar which is good for storage, it can be popular. The tree is moderately or slightly vigorous, fruits mostly on old laterals. Flowers early, therefore it can be damaged by spring frosts. Has a good fruitfulness, can produce a medium yield even after flower frost damage. Its flowering time is early, its good pollinator is ‘Hosui‘. Resistant against fire blight.
 
 
2.19.abra Shinko
 
Figure 2.19.: Shinko (Photo: Krisztina Honty)
 
Shinseiki
It was created by crossing ‘Nijisseiki’ x ‘Chojuro’ in 1945. It is recommended for growers instead of ‘Nijisseiki’. It can be harvested in the first week of August, a couple of days after ‘Kosui’. Its fruit is mid-large (200 g), with a flattened round shape. The skin is smooth, yellowish green with conspicuous lenticels. Very showy. The flesh is firm, crunchy. Its light-coloured skin is not so susceptible as that of ‘Nijisseiki’. The tree is highly vigorous, bears fruit mostly on long laterals. Flowers in the medium period, its good pollinator is ‘Hosui’. Has an early onset and a medium fruitfulness, but yields regularly.
 
 
2.20
 
Figure 2.20.: Shinseiki (Source: http://www.penrynorchardspecialties.com)
 
 
2.8. Control questions:
1. When did pear cultivation start approximately and on which continents?
2. When did pear cultivation start in each continents?
3. Briefly describe the history of conscious pear breeding from the beginning until present.
4. Which are the main gene sources participating in the development of European pear?
5. Which are the main gene sources participating in the development of Asian pear?
6. How can you describe the ploidy of pear cultivars?
7. Describe with cultivar examples the main methods of pear breeding!
8. Describe the major aims of pear breeding, mentioning the requirements for European and Asian pears!
9. Describe briefly the present position of pear cultivar use!
10. Describe the most important characteristics of ‘Harrow Delight’!
11. Describe the most important characteristics of ‘Harrow Sweet’!
12. Describe the most important characteristics of ‘Harvest Queen’!
13. Describe the most important characteristics of ‘Monglow’!
14. List at least three red skin pear varieties and describe one of these!
15. Compare the major characteristics of ‘Concorde’ and ‘Conference’ regarding cultivation aspects!
16. Describe the most important characteristics of ‘Eldorado’!
17. Describe the special characteristics of Japanese pear which are different from those of European pear!
18. Describe the ecological needs of Japanese pear!
19. Describe the most important characteristics of ‘Hosui’!
20. Describe the most important characteristics of ‘Kosui’!
21. Describe the most important characteristics of ‘Shinko’!
22. Describe the most important characteristics of ‘Shinseiki’!
 
 
 
References:
 
Bell, R. L., Quamme, H. A., Layne, R. E. C., Skirvin, R. M. 1996. Pears. p. 441–514. In: Janick, J.–Moore, J. N. (eds.). Fruit breeding. 1. Tree and tropical fruits. John Wiley & Sons, Inc., New York.
Brewer, L.R., Palmer, J.W.(2010): Global pear breeding programmes: goals, trends and progress for new cultivars and new rootstocks. Acta Hortic. 909. http://www.actahort.org.
Fischer, M. 2009. Pear breeding. pp. 135–160. in: Editors: Priyadarshan, P. M. és Mohan Jain, S.: Breeding Plantation Tree Crops: Temperate Species. Springer.
Göndör J-né (szerk.) 2000. Körte. Mezőgazda Kiadó, Budapest.
Göndör J-né 2001. Japán körte – nasi. p. 144–150. in: Tóth M. (szerk.) Gyümölcsészet. Átdolgozott és bővített kiadás. Primom Kiadó. Nyíregyháza.
Hancock, J. F.,Lobos, G. A. 2008: Pears. p. 299–336. in: Hancock, J. F. (ed.): Temperature fruit breeding. Springer, East Lansing, USA.
F. Paprštein, F., Blažek, J., Bouma, J. New pear cultivars from the Czech Republic. Acta Hortic. 814. http://www.actahort.org.
Silva, J.M. Barba, N.G., Barros, M.T., Torres-Paulo, A. 2005. 'Rocha', the pear from Portugal. Acta Hortic. 671. http://www.actahort.org
 
 

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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.

TÁMOP-4.1.2.A/1-11/1-2011-0028

Félidő

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

 

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Utolsó frissítés: 2014 11. 13.