Intraspecific variability overlays abiotic site effects on some quality parameters of walnut (Juglans regia L.) fruits from Kyrgyzstan

Abstract

Kyrgyz walnut-fruit forests harbour a unique walnut diversity, which has rarely been investigated concerning nut properties and the influence of environmental conditions on these. We evaluated the influence of soil properties and altitude on physical and some chemical walnut properties at three sampling sites differing in altitude by 200 m. Walnut samples were collected from 15 randomly chosen trees. Soil samples from two depths under each tree were analysed for plant available mineral nutrients and soil chemical properties. In contrast to our hypothesis, physical nut and chemical kernel quality parameters did not differ between sampling sites at different altitude and were not affected by soil properties. Only pH showed a relationship with manganese availability in soil and kernel content, and was related to amino acid content of kernels. Tree and site-specific variability overrides abiotic influence caused by different altitude or soil properties and reflect the high genetic variability in these forests.