Relationships of Shading-Induced Reductions in Yield and Morphological Traits with Mineral Nutrition of Apple Trees

Abstract

Protective nets are commonly used in orchards to prevent hail damage and sunburns. However, these nets partially prevent sunlight exposure of the trees. Sunlight directly influences plant physiology. In present study, the effects of reduced sunlight on mineral nutrition of trees were investigated. Experimental orchard had protective nets with different shading ratios (0, 32, 42 and 56%) for 7 years. In 8, 9 and 10th year of the orchard, to reveal relationships of protective nets and mineral nutrition, apple trees were sampled from part of leaves, bud, and flower and subjected to mineral analyses. Leaf nutrients were all influenced by light intensity and increasing N, K, Fe, Cu, Mn and B levels were observed with increasing shading ratios. In fruit buds, shading treatments all had more Ca, Fe and Cu concentrations. In flower samples, only P and Mg were found to be significant and the lowest values were obtained from the greatest shading ratio. Nutrient ratios were assessed for each sample group and only the leaf nutrient ratios were found to be significant. It was observed when the common ratios (N:K and K:Mg) were assessed that the greatest N:K ratio was obtained from the control treatment and the other treatments were placed into the same group; the lowest K:Mg ratio was obtained from the control treatment and the other treatments were placed into the same group. It couldn’t be detected any relationships between decreasing yield, morphological traits and reduced sunlight with nutrient contents based on concentrations under experiment conditions.