The article presents the results of 20 years of research on the implementation of a project to create pear varieties and complex donors of monogenously determined dwarfism (gene D) with high winter hardiness, group resistance to fungal diseases — scab (Venturia pirina Aderh., brownish (Entomosporium maculatum Lev.) and Septoria (Septoria piricola Desm.) and bright red color of fruits (gene C). The research was conducted according to generally accepted methods in the pear breeding gardens of Russian Research Institute for Fruit Crop Breeding in 2000-2019. The study objects were populations of hybrid pear seedlings obtained from targeted crosses of highly adaptive forms and hybrids of pears with descendants of the 4th generation of the Karlikovaya Zelyonaya variety (Nain Vert), heterozygous for the dwarfism gene (Dd) in the first stage, and hybrid seedlings from crossing a DK-2 donor with sources of good fruit taste in the second stage. The aim of the research was to identify winter-hardy complex donors of dwarfism for further use in breeding programs for the creation of intensive pear varieties. Seedlings were grown using conventional technology in a breeding garden on a plot with dark gray forest soil. As a result of research for further use in breeding as complex donors of dwarfism, winter hardiness, group resistance to fungal diseases and red color of fruits, 3 forms were selected in the second stage of crosses (DK-1-6-57, DK-1-674, DK-1-4-38). Their use in long-term innovative breeding programs for the creation of intensive pear varieties will allow to conduct rejections at the early stages of ontogenesis and thereby to reduce the volume of hybrid families by 2-4 times. These complex donors are briefly characterized.
The results of the study of the resistance to rust (Gymnosporangium sabinae (Dicks.) G. Winter) of pear cultivars, forms and intergeneric hybrids with different genetic origin as well as economical and biological characteristics of identified absolutely resistant genotypes are given. The studies were carried out in 2012-2020 in the pear collection orchard with the aim of to reveal genetic donors and sources of absolute resistance to rust for the further use in breeding programs. The work was carried out in accordance with the Program and Methods of Fruit, Berry and Nut Crop Breeding and Program and Methods of Fruit, Berry and Nut Crop Variety Investigation. Four intergeneric hybrids (Malopyrus № 1, Pyromalus № 818, Sorbopyrus auricularis, Sorbopyrus Kuryanovii); 114 pear genotypes of different genetic origin including pear cultivars and forms of Pyrus communis L., Pyrus pyrifolia (Burm) Nakai, Pyrus ussuriensis Maxim.; cultivars that are interspecific hybrids of Pyrus communis and Pyrus ussuriensis; Pyrus salicifolia Pall. and Pyrus calleryana Decne. as well as 2800 hybrid seedlings were used as objects for the research. As a result it was determined that all cultivars and hybrid seedlings used in the work regardless of their genetic origin were susceptible to pear rust: cultivars and forms derived from Pyrus communis, Pyrus ussuriensis, Pyrus pyrifolia and interspecific hybrids within the Pyrus L. genus. Intergeneric hybrids of pear with apple, apple with pear, pear with mountain ash and pear with whitebeam showed absolute resistance to the pathogen. Four intergeneric hybrids Malopyrus № 1, Pyromalus № 818, Sorbopyrus auricularis, Sorbopyrus Kuryanovii were allocated as sources for future use in breeding for high resistance to pear rust.
Development of low-growing varieties is one of the prioritized directions in groups selection. Solution of excessive growth in the selection can be solved in today’s conditions by two means: on a polygenic and on a monogenic level. Up until recently such work was performed by research institutes of horticulture in the U.S.S.R. and Russian Federation only on the polygenic level. The analysis is performed for the data of 17 summer studies on the development of complex donors of monogenic determined dwarfness (gene D), high winter hardiness, group fungal disease resistance (scab, leaf spot and Septoria blight) and bright red coloration of pear fruits (gene C). On the first stage of these studies the issue of the development of population of hybrid dwarf types with high adaptive potential in the conditions of the Central Black Earth region of Russia was solved based on a hybridization of the donors of high winter hardiness and fungal disease resistance with the donors of monogenic determined dwarfness which were the descendants of 4th generation of the NainVert variety. As a result, several complex donors were selected. Its use in long-term pear selection programs would make sorting process possible on earlier stages of the ontogenesis and thanks to that would make it possible to halve the size of hybrid funds. Brief description of the complex donors is given.
The results of the study of the aesthetic characteristics of 6 genotypes of decorative pear (17-43-30, 17-43-36, Alaya, Sharovidnaya, DK-2 and DK-3) are presented. The research was carried out at VNIISPK in 2012-2014, using a modern method for assessing the decorativeness of research objects. The most decorative for the sum of points was the DK-2 genotype, which received a score of 25 points. The Alaya variety was decorative at the average degree. Sharovidnaya, 17-43-30, 17-43-36, DK-3 were the least decorative. Some varieties, including those having a low total score, have one or several distinctive decorative features and can be successfully used in the landscape compositions in which these characters are important. The studied pear varieties in various degrees are characterized by valuable decorative qualities. Restrained growth peculiar for 2 genotypes (DK-2, Sharovidnaya). The spherical crown habitus is characteristic for 3 objects (17-43-30, 17-43-36, Sharovidnaya). DK-2 and DK-3 have a crown of a conical shape. A high intensity of flowering was observed in DK-2. Anthocyanin color of fruits is inherent in Alaya. Most of the studied varieties (17-43-30, 17-43-36, Sharovidnaya, DK-2, DK-3) retain ornamentality throughout the whole year. DK-2 can be the most attractive for landscaping purposes. It has the highest sum of decorativeness points and a set of morphological features valuable for the needs of landscape design and preserves the aesthetic appeal and originality of the appearance during the whole year.
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