The effect of foliar feeding on physiological condition of apple trees and chemical content of fruits

Abstract

Chemical content of leaves and fruits of the low growing apple trees on the rootstocks SК4 and М9 in the result of application of foliar feeding with water solutions of various mineral fertilizers was studied. Special ballastless multi-nutrient fertilizers in solid and liquid forms containing a wide range of chelated microelements were used. The effect of foliar feeding on the content in plants and fruits of macro- and microelements at the fruit maturity stage was estimated with the help of the method of leaf analysis. Significant stable increase of the content of nitrogen and potassium was observed in the leaves of apple trees on the rootstocks SК4 and М9. The content of potassium and calcium in apples became higher. With the help of statistical analysis it is shown that there exists close correlation between the content of elements in leaves and fruits: (N) r = 0.79; (K) r = 0.77; (Ca) r = 0.94; (Cu) r = 0.75; (Mn) r = 0.89; (Zn) r = 0.75; (B) r = 0.70. In the result of our physiological and biochemical tests positive effect of mineral feeding on the functional condition of apple trees during summer season when being subjected to intensive hydrothermal stress factors was established. The foliar feeding effect appeared as changing of the ratio of water fractions in the apple tree leaves at the background of increasing atmospheric drought, which in some years in July and August reached the criteria of "hazardous weather". Sufficient level of water content in the cells of apple trees on the rootstocks SК4 and М9 in case of foliar application of fertilizers was ensured as a result of bound water increasing. Statistic analysis of the experimental data showed significant changes in the ratio of bound and free water fractions. In August, in the environment of strong impact of negative abiotic factors, at higher level of water content in the tissues it was found that the content of pigments in leaves was much higher than in the reference version. The functional changes confirm that application of mineral nutrients contributes to activation of the adaptation mechanism. When foliar feeding is used the content of biologically active substances in apples is the highest: content of vitamin C increases by 13.6 - 15.2%, vitamin Р - by 8.7 - 24.6%.