Influence of Soil Extractable Plant Nutrients on the Walnut Kernel Ionome in Southern Kyrgyzstan at Different Elevations

Abstract Background and Aims Climate change causes altered precipitation patterns and temperature increases, which may affect food quantity and quality. In Kyrgyzstan anticipated temperature changes are expected to influence the physiology of walnuts ( Juglans regia L.) and soil properties relevant to plant nutrition, thereby impacting walnut fruit quality. This study explores the relationship between plant available nutrients in soil and walnut fruit nutrient content as affected by future temperature changes. Methods The soil samples were collected in the walnut forests of Southern Kyrgyzstan from top- and subsoils at three elevation levels (1000, 1300, and 1600 m above sea level). The walnut samples were collected from the same sampling sites and both soil Mehlich-3 extracts and acid digests of walnut fruits analyzed by ICP-OES. Results The results revealed no consistent relationship between Mehlich-3 extractable elements and walnut extractable elements, except for a weak negative correlation with zinc (Zn). Stronger relationships were observed among soil elements, but no clear associations with elevation levels were found. The walnut kernel ionome exhibited differences, particularly in calcium (Ca) and potassium (K) concentrations, with the low elevation site showing higher Ca and lower K concentrations compared to the high elevation site. Conclusions Differences in average temperature as caused by elevation did not affect available plant nutrients in the soil but altered the walnut kernel ionome and thus affected the walnut quality in the investigated forest systems. Future investigations should focus on climate change effects, such as altered precipitation patterns and drought, which may impact walnut fruit development and kernel properties.