Seed productivity of Rosaceae species used as rootstocks in the conditions of forest-steppe of Western Siberia

The research objective was to estimate the possibilities of receiving seeds of stocks for some fruit and decorative crops in the conditions of the forest-steppe of Western Siberia. The possibilities of receiving seed material of Sorbus sibirica, Malus baccata and Rosa majalis in the places of natural growth, and also collecting the fruits of Pyrus ussuriensis from trees created at growth of rootstock shoots after the death of high-quality grafted part were considered. The indicators of potential and real seed efficiency, and also the coefficient of efficiency were of great importance for the assessment of adaptive potential of types introduced species. At representatives of local flora the coefficients of seed efficiency were used for the definition of the influence of hydrothermal conditions of the concrete periods of vegetation on fructification. During studying of 2017-2019 the coefficient of the efficiency of Rosa majalis varied from 67.03 to 79.11. The maximum value of the coefficient of efficiency of the type introduced species of Pyrus ussuriensis - 54.20 that can be connected with early blossoming and the lack of sufficient number of pollinators in cool weather. The indicators important for forecasting of quantity of saplings of stocks, - the mass of the fruit and number of executed seeds in it were allocated. From 1 kg of collected fruits of Pyrus ussuriensis it was possible to allocate about 90 pieces of executed seeds, Sorbus sibirica - about 6 500 pieces, Malus baccata - about 9 000 pieces. These data have to be corrected depending on field and laboratory viability of the objects ((with different methods of overcoming dormancy). Studied representatives of the Maloideae subfamily were characterized by dormant types B2 or B3, due to physiological mechanism of inhibition, which required long-term cold stratification or treatment with hormones. For studied representatives of the subfamily of Maloideae the types of rest of B2 or B3 caused by physiological braking mechanism were characteristic, overcoming it requires long cold stratification or processing by hormones. Rosa majalis has a combined resting type (A2-B3) with a strong inhibitory effect of the pericarp.