Pyrus originated in the mountainous area of western China in Cenozoic, and there are also extremely rich types of Pyrinae in this area, which are distributed along the mountain. Due to the geographical isolation in mountainous areas and the different ecological conditions such as cold and drought, the genus Pyrus has evolved into two major pear lines: Oriental and Western, and at the same time formed three origin centers of cultivated pears in the world: ① China Center; ② Central Asia Center; ③ West Asia Center. Under the action of natural hybridization and spontaneous mutation, complex and diverse species, varieties and types of Pyrus plants have been produced.
The characteristic of Pyrinae is that the chromosome number is 17, while the chromosome number of other subfamilies of Rosaceae (except Malinae) is 7 ~ 9. It is generally believed that Pyrinae is diploid and originated from two types of Rosaceae, one of which has a chromosome number of 8; The other is 9. For a long time, people have always thought that the wild species of Pyrus is diploid, and it is a morphological species without chromosome changes. Triploids were also found in the apricot pear Yü and the dry pear 244208ü of Pu (1985), indicating that the evolution of wild pears also changed the chromosome number.
Varieties of pears
There are about 30 species of Pyrus plants in the world, including 12 species in the west and 16 species in the east (see table 1 and table 2).
Among these varieties, western pear is the main cultivated variety in Europe, North America, South America, Africa and Oceania. Sydney is also cultivated in a small amount in Europe, mainly for pear wine. The rest are only used as rootstocks and ornamental purposes, and almost none are cultivated as fruit trees.
Column, Syria, Lebanon (P.syriacaBoiss.), Tunisia, Libya, Israeli Syrian pear (P.saliofoliaPall.), Yilan in the north, Suliu pear in the south (P.elaeagrifoliaPall.), Turkey, Soviet Union, Elaeagnus Elaeagnus, Southeast Europe, Sardinia (P. Amygdaformisvi/kl). Greece, South Slara almond-shaped pear (P.regeliiRehd.), Afghanistan Regerisia population (P.mamorensisTrab.), Morocco Mamorun pear (P.gharbianaTrab.), Morocco Chabina pear (P.longgipesCossetDur.) Algerian Langjip pear population in North Africa (P.cordataDesv.) French, Spanish heart-shaped pear (p. nivalis)2 ICQ.) Western Europe, Central Europe, Southern Europe Sydney (P.caucasicaFed pear.) Western Europe, Southeast Europe, Turkey, European population distribution of western pears and varieties.
Table 1
Table 2
Table 2
In the Oriental pear system, Pak Lei, Qiuzi pear and Xinjiang pear are also the main economic cultivars in China, Japan and North Korea. Shali and Qiuzi pears also have a large number of wild resources and are widely used as rootstocks. Other kinds of oriental pears are wild or semi-wild species, which are mainly used for rootstocks and ornamental purposes.
Pear varieties are an important part of pear germplasm resources, which belong to five varieties: Xiyang pear, Shali pear, Pak Lei pear, Qiuzi pear and Xinjiang pear, and are also the main body of pear cultivation at present.
There are at least three varieties of western pears, namely Elaeagnus mollis, willow pear and Syrian pear. Like cold and dry, but not cold-resistant. The tree stands upright, forming a conical crown. The leaves are small, and the edges are rounded and obtuse. The fruit stalk is short and thick, mostly gourd-shaped or obovate, mostly persistent calyx. This kind of fruit can only be eaten when it is ripe and softened. The biggest feature is that the pulp is creamy when it becomes soft, smooth and soluble at the entrance, sweet in taste and rich in aroma. Representative varieties are bartlett, Enjiu, Bauske, Conference and klapp's favorites. The triploid varieties are Bree Amanris, Bree Dyer, Pity maston Duchess, Spina De Corpi, Jodl Shengli and Cure. Tetraploid varieties include Daba pear and Daenjiu pear.
Sand pear varieties are suitable for warm and humid climate, with strong heat and drought resistance and weak cold resistance. The tree is upright; The branches are stout, the leaves are large, and the edges have spiny serrations. The fruit is generally round or nearly spherical, with long pedicels and sepals falling off. You can eat the immature fruit, which is sweet, crisp, dense and less fragrant. The representative varieties of pears in China are Yiwu Zaosanhua, Yanzhou Sydney, Zhenghe Grand Sydney, Guanyang Sydney, Cangxi Pear and Chenggong Zhubaoli Pear, while Japanese pears are Taibai, Twentieth Century, Jushui, Ergongbai, New Century and Fengshui. Among them, the triploid varieties are Wuyuan Daye Sydney and Siyang Huanggai pear. Tetraploid varieties include Shinjiro and Tosa Brocade.
At present, no wild variety has been found in Pak Lei, but Akio Kikuchi thinks it is a hybrid variety of Du pear and Sha pear. The cold resistance is weaker than Qiuzi pear and stronger than Shali pear. Frostbite usually occurs when the temperature is below -25℃. The tree is open, the branches are dark purple-brown, the leaves are large, the edges have sharp serrations, the teeth are slightly closed inward, the fruit is generally round or oblong, the sepals fall off, and it can be eaten immature. Crispy and juicy, with few stone cells, slightly fragrant and storage-resistant. The representative varieties are Yanbian Apple Pear, Suizhongqiu Pak Lei, Dingxian Yali Pear, Zhaoxian Sydney and Laiyang Pear. Among them, the triploid varieties are Siyang Dashuihe pear, Haitang crisp pear and Suining soft branch pear; Tetraploid varieties include Jinxian Dayan pear.
Qiuzi pear varieties have the strongest cold resistance and can tolerate the low temperature of -50℃. Strong resistance to scab and leaf spot. The crown is broad, the branches are light and gray-brown, the leaves are large, and the edges have sharp serrated thorns. Most fruits are very small. It is round or oblate, with persistent calyx, and can only be eaten after it is mature. It is a kind of soft meat with thick texture, many stone cells, sweet and sour taste and rich flavor, and most of it is not resistant to storage. The representative varieties are perfume, full garden fragrance, Balixiang, pointed autumn pear and so on. The varieties with good flavor are Jing Pak Lei and Nanguo pear. Among them, the triploid variety is Xingcheng Anli; Lanzhou soft pear; Yuzhong peel embryo fruit, etc.
Xinjiang pear variety is a new variety formed by interspecific hybridization between Xiyang pear and Pak Lei. Like cold and dry, strong cold resistance and wide adaptability. The crown is semi-circular, the branches are medium in color, the upper part of the leaf margin has fine sharp teeth, and the lower part or base has shallow or blunt serrations. The fruit is large, ladle-shaped or oval, with persistent sepals, soft meat and crisp meat, which are generally not resistant to storage and transportation. Representative varieties are Korla fragrant pears; Lanzhou Flower Pear; Guide pears, etc. Among them, the triploid varieties are Wuwei Zhutou pear, Xikezeke pear and Aksu Hongnahe pear. The tetraploid variety is Bazhousha -0 1 Xiangli.
In addition, there are some varieties of Sichuan fragrant pears in southwest China and northern India. These varieties adapt to the hot and humid climate. The fruit is of medium size. Compared with other pears, the quality and flavor are average. Some cultivated varieties of black pear have dark brown or even black fruits.
Related plants of pear
The dwarf rootstock of pear has long been a related plant of different genera. These plants include apples. ), prickly fruit. , Tang Di (spp. ), heather DC. And Castanopsis species. But in production practice,
As a dwarf rootstock of pear, Lirong has a history of nearly 400 years. It has many types, including QA, QB and QC. QA has strong growth, resistance to leaf spot, easy rooting by layering cutting, developed fibrous roots and good soil fixation as a rootstock. The growth potential of QB is slightly weak, the layering cutting has good rooting, less fibrous roots and the grafted crown is slightly smaller than QA. QC crown is short, waxy platform, weak cold resistance. It is easy to be infected with leaf spot, layering and hardwood cutting are easy to take root, and the root system is small and shallow. The grafted crown is smaller than QA and QB, and bears fruit earlier.
As a dwarf rootstock, quince has the disadvantages of weak affinity and cold resistance. To this end, many countries are cultivating new types. The famous new models are BA-C-9 in France, CTS2 1 1 in Italy, BW20 and BW 1 1 in Switzerland, and S 1 and S3 in Poland.
Study on Pear Germplasm Resources
It was gradually formed on the basis of scientific research on fruit trees in the 1920s and research on raw materials in the 1950s. Its research contents mainly include collection, preservation, evaluation and utilization. In order to systematically study pear germplasm resources, countries all over the world began to collect pear germplasm resources from the beginning of 19 century. Among them, Corvallia Experimental Station in Oregon, USA has systematically collected pear germplasm resources from more than 20 countries in the world since 19 12.
On the basis of years' collection in Covalis experimental station (1984), a pear germplasm bank was established. At present, there are 382 species and varieties of Pyrus/kloc-0, and 363 species of Pyrus related plants. In addition, there is a national fruit tree variety test station in Kent, England, which has collected and preserved more than 600 varieties. Michurin Fruit Research Institute of Lenin Academy of Sciences of the Soviet Union also collects and preserves pear varieties. But these preservation centers mainly collect and preserve western pears. China is the largest in the collection and preservation of oriental pears. In the early 1950s, China also carried out a large-scale investigation of pear variety resources. The wild species, types, local varieties and rare varieties investigated were collected by local scientific research institutes and experimental stations, with about 3000 varieties. The Fruit Research Institute of China Academy of Agricultural Sciences has the largest germplasm resources garden in China. The resource park covers an area of 177 mu, and has collected 18 kinds, 60 types and 64 1 variety of pears. Among them, there are nearly 600 oriental pear varieties. There are more than 300 varieties of oriental pears in the fruit tree experimental station of Japan's Ministry of Agriculture and Forestry. Some countries have also compiled "Pear Tree Records", such as He Derrick of the United States, which recorded 80 varieties in detail; There are 2836 varieties; The Chronology of Pear Trees (1962) compiled by Smirnko (симиенко) of the Soviet Union * * * describes 568 varieties. The third volume of Records of china fruit-Pear (1963) compiled by the Fruit Research Institute of China Academy of Agricultural Sciences describes 1000 varieties of eastern and western pears. Among them, there are 72 varieties of Qiuzi pear, 459 varieties of Pak Lei pear, 452 varieties of Shari pear, 29 varieties of Xinjiang pear and 0/0 varieties of Sichuan pear. In addition, 22 western pear varieties and 65,438+05 Japanese pear varieties were described.
The main pear-producing countries in the world have successively carried out the identification of pear germplasm resources, among which the identification of American national germplasm bank is more systematic.
After 1950, China did some work in the investigation and study of specific figures. Since 1980s, the identification and evaluation of specific traits have been carried out systematically. Through investigation and study, the cold-resistant varieties of pears are Anli, Sweet Pear and Longxiang Pear in Qiuzi, and most varieties of pears in the west are resistant to scab, such as Kangfruns, Ririhong Pear and Angulimu Pear, as well as Pak Lei's Honey Pear, Golden Pineapple Pear, Zaosu Pear, Silver Pear and Fetal Yellow Pear. The varieties with strong drought tolerance are Guifei, Kant, Marjorie and Ole. The varieties with strong drought tolerance are Fetal Yellow Pear, Huangxian Changba Pear, Laiyang Li Mao Pear, Bali Pear and Shan Zhi Pear. In addition, among the wild species used as rootstocks, Lidu pear has strong cold tolerance, drought tolerance, waterlogging tolerance and saline-alkali tolerance. Li Dou is suitable for growing in warm and humid climate and has high immunity to pear rot, so it is suitable as the rootstock of sand pear. Using Mali as rootstock has high yield, long life and strong affinity (see tables 3 and 4).
Table 3
Table 4 Looking for dwarf rootstock resources from pear plants, it has been found that Korean pear, heart-shaped pear, Japanese pear, Reggie pear and Langjipu pear all have dwarf potential. Clonal rootstocks OPR2 1 1, OPR249 and OPR 157 screened from Lidou pear have great advantages as dwarfing rootstocks, because they are compatible with all pears, especially Oriental pears, and have good soil consolidation effect. At the same time, the dwarf variety resources of pear have also been paid attention to. There are seven dwarf varieties in the United States, including US309, Neinevett and the semi-dwarf Packhams Triumph in Britain. There are more than 30 varieties such as аннабретан in the Soviet Union, and 57-3 1-5 in China. Compact s 1 ~ S6 series.
Using interspecific hybridization between Pyrus pyrifolia and Pyrus pyrifolia varieties resistant to fire blight, the United States bred varieties such as Kiefer, Kant and Jiabao in the 1930s, which enhanced their resistance and were more suitable for processing and canning, and developed for many years. Disease-resistant varieties Magris, Liming and Mengnuo were obtained by crossing Qiuzi pear blood seedling line with Xiyang pear. The fruit is large and of good quality, and it is being popularized and applied.
Fruit Research Institute of China Academy of Agricultural Sciences uses the cold resistance of Qiuzi pear to improve the cold resistance of Xiyang pear. Nanguo pear and Bali pear were crossed to breed a new variety of Jinxiang pear, which has the flavor of Qiuzi pear and Xiyang pear, can safely overwinter in western Liaoning, and does not suffer from the unique rot disease of Xiyang pear in northeast China. All countries are making full use of pear germplasm resources and seeking to further increase pear yield.