Morphological and biological peculiarities of sweet cherry productivity development in the south of the Non-Chernozem zone

Sweet cherry ( Cerasus avium L. Moench) is a valuable fruit crop; its industrial planting is concentrated mainly in the South of Russia because of insufficient winter hardiness. Nowadays, 16 varieties have been adapted in the Non-Chernozem zone, and 11 varieties bred in the Russian Lupin Research Institute are under the testing. A deep understanding of the patterns of development and formation of the yield components allows for a better use of genetic potential of the species. This study, for the first time, revealed the significant variability in morphobiological indices of new sweet cherry varieties in the Non-Chernozem zone conditions, which provides new possibilities for genotype selection and commercial planting. The yield components are shown to be related to each other but only some correlations are significantly valid. The cluster analysis grouped the varieties by growth and fruiting similarity, and the factors with the highest contribution were found. The work aimed to study morphobiological parameters determining productivity of sweet cherry plants and to highlight genotypes which are valuable for breeding and commercial use. The experiment estimated 23 sweet cherry varieties for 9 morphobiological traits, i.e., the number of annual shoots, the average length of annual shoots, the number of sprays (“May bouquets”), the number of flower buds per annual shoot, the number of flower buds per sprays, the number of flowers per flower bud, yield, crown width, trunk circle (the garden experimental plots, the All-Russian Lupine Research Institute, Bryansk Province, 1991-1996). Estimation of variation coefficients allowed us to classify the varieties into two groups. The first group consists of varieties with high variation degree (more than 10 %) of such correlated traits as the number of annual shoots, the average length of annual shoots, the number of sprays, the number of flower buds per annual shoots and the number of flower buds per sprays. In this group, the varieties Podarok Petelinu, Teremoshka, Bryanochka, 2-3-67, 2-6-36, 2-3-45, Odrinka, Krasnaya plotnaya, Yantarnaya, 2-5-2 and 2-3-35 formed correlation pleiades. The pleiades had different power and strength. The varieties of this group are appropriate for breeding for a complex of economic valuable traits. The all tested genotypes made the second group with the variation degree for the number of flowers per flower bud ( Cv = 1.0-6.0 %), crown width ( Cv = 2.0-5.0 %), and trunk circle ( Cv = 0.3-0.4 %) less than 6 %. Only seven of 36 pair correlations are significant. The significant pair correlations are the average length of annual shoots-the number of annual shoots ( r = -0.49, p = 0.016); the average length of annual shoots-the number of sprays ( r = 0.73, p = 0.000); the average length of annual shoots-crown width ( r = 0.74, p = 0.000); the average length of annual shoots-trunk circle ( r = 0.42, p = 0.044); the number of annual shoots-the number of flower buds per annual shoots ( r = 0.77, p = 0.000); the number of sprays-crown width ( r = 0.59, p = 0.003); crown width-trunk circle ( r = 0.54, p = 0.008). There is no link between the yield and its components. The cluster analysis resulted in four clusters grouping the varieties that are similar in terms of the generalized indicator of the studied traits. It makes easier to select initial lines for breeding. The lack of the significant valid correlations between yield and morphological traits made us to apply the factor analysis which revealed four factors with eigenvalues of > 1. The contributions of these factors to the observed variability are 35.9, 18.6, 11.9, and 11.5 %. The other four factors can be regarded as scree ones.