ABSTRACT
Drought and heat stress are significant factors limiting fruit crop yield in arid conditions. Foliar fertilization is a common practice of supplying fruit crop production with mineral nutrients, especially under limited soil nutrient availability conditions. To evaluate potential effectiveness of the foliar application of macro-, micronutrient and growth regulators on dynamics of physiological parameters of the pear and apple cultivars under abiotic stresses, three-year experiments were carried out under arid conditions at the Russian Research Institute of Arid Agriculture during the 2015-2017 growing seasons. It has been revealed that foliar nutrition reduces the negative influence of heat stress, stabilizes the functional state of plants, thereby enhancing resistance to drought. During the most severe drought periods of vegetation, under the influence of foliar nutrition, there was a significant increase in the total water content (TWC), relative leaf turgidity (RLT) and water retention capacity (WRC); and also index of leaf water deficiency (LWD) was improved as compared to the non-treated control. All foliar treatments involving the macro-, micronutrient and growth regulators significantly enhanced fruit crop yield of pear and apple varieties over the control, yield enhancement was obtained 2.7-22.0 t ha-1 for the Talgar beauty (pear variety), 2.2-19.3 t ha-1 for the Renet Symirenko (apple variety), and 1.6-10.5 t ha-1 for the Starkrimson (apple variety). The most effective treatments for water consumption coefficient (WCC) were plantafol and speedphol. The results suggest that foliar plantafol and speedfol could be used as part of an efficient, sustainable fertilizer program for apple and pear trees for maintaining or improving fruit quality, productivity, and avoiding negative efficacy of abiotic stresses.
