Productivity and ecological plasticity of plum ( Prunus domestica) varieties under environmental instability

In perennial crops, particularly in plum trees, a genotypic (varietal) ecological plasticity as the ability to respond to external changes and anthropogenic factors is little studied. Plum tree is one of the most adaptive and wide spread fruit crop peculiar in its drought resistance, winter hardiness, high and sustainable fruit production. However, plum varieties significantly differ in valuable traits and ecological plasticity. Here we show the data on yield, fruit size and plasticity of differently originated plum varieties under conditions of four soil and climatic zones of Krasnodarskii krai. The data were obtained by statistical processing results of varietal testing. The main regional varieties Kabardinskaya rannyaya, Renklod Altana, Vengerka italianskaya, Anna Shpet, Vengerka azhanskaya and Tuley Gras were assessed. The role of the genotype in adaptation to environment indicated by fruit size and yield as an integrated parameters of the response to adverse condition was studied. In some varieties the yield varied from 18.0 до 50.0 centner per ha but did no exceed an average value for all varieties in each zone. Higher average yield for all zones was observed in Stenley variety at 165-170 centner per ha, in Anna Shpet variety at 115-145 centner per ha, in Kabardinskaya rannyaya variety at 130.4-147.9 centner per ha, and it was a little bit lower in Renklod Altana and Tuley Gras while the lowest in Vengerka azhanskaya and Vengerka italianskaya varieties. The yield was shown to be specific to genotype as a varietal biological peculiarity influencing the yield at 51.6 % rate, and also it depends on weather condition of the year with 28.7 % influence, and on their interaction at 17.2 % influence. Definite effects were shown for additional factors such as scheme of planting, type of crown, mineral nutrition, protection measures against diseases and pests. Fruit size was shown to be a varietal parameter closely related to the weather conditions and stresses during vegetation such as heat and water deficit at the phases of ovary and fruit formation and maturation. According to fruit size the rate of influence for weather, variety and their interaction was 41.6 %, 37.5 % and 20.8 %, respectively. Calculated regression coefficient b 1 for the yield value was > 1, thus the tested plum varieties were characterized as intensive and responding to new technologies such as dense planting schemes, flattened crowns, integrated protection, etc. The Kabardinskaya rannyaya and Stenley plum varieties being the most plastic, adaptive and productive were selected as basic for commercial assortment of plum trees in the conditions of the southern gardening.