Resistance of domestic plum tree rootstocks against periodic overwatering of floodplain soils

Abstract

This work investigates the effect of domestic plum rootstocks on the stability and productivity of Stanley plum plants. The main factor limiting the productivity of fruit crops in the floodplain soils of the foothill horticultural area of Krasnodar Oblast was found to be an unfavorable water-air regime of these soils in wet periods. The main geogenic factors that negatively affect the state and productivity of plum plants include the following: the presence of layers of low fertility and medium-clay granulometric composition in the soil profile. Depression and death of trees is promoted by prolonged overwatering of the upper part of the soil profile, caused by low filtration capacity of soil layers in combination with heavy granulometric composition and conditions of laying on the terrain (absence of horizontal surface runoff). A different degree of plum trees resistance to these unfavorable geogenic conditions depending on the type of rootstock was revealed. The lowest degree of depression under prolonged overwatering of the root-containing soil layer was observed in plum trees on the PK SK2 rootstock, which demonstrated the highest vegetative mass growth under the smallest number of dead plants. Stanley plum trees on rootstock AP1 were subjected to the greatest depression. The different degree of plum tree stability on different rootstocks is mainly related to the location of potentially active roots in the soil. The root system of plum trees on rootstock PK SK2 is characterized by the concentration of the main part (about 65 %) of potentially active roots in the upper soil layer of 0–40 cm. In plum trees on AP1 rootstock, potentially active roots penetrate to greater depths, with about 60% of the roots located in the soil layer of 40-80 cm. During wet periods and after abundant precipitation, when the soil below the 40 cm level is saturated with moisture, more than half of potentially active roots of plum trees on AP1 rootstock have to survive in unfavorable conditions.