Preliminary Survey on the Cause of Withered and Die off of Apple Leaf in Qin`an County of Gansu

The apple leaf and soil in orchard of Qin′an county of Gansu were investigated.The results indicated that total potassium content of leaf was 9.2 g/kg,sodium content of leaf was 315 mg/kg in health orchard,K~+/Na~+ ratio was 29.2.But total potassium of leaf was 4.2 g/kg,and sodium content of leaf was 3 900 mg/kg in leaf marginal withered orchard,K~+/Na~+ ratio was 1.1,it was less 26.5 times than the health orchard.Soil pH was 8.2 in health orchard,it was less 0.4 units than the leaf marginal withered orchard.And the water-soluble sodium in health orchard was less 84.9 mg/kg than that in leaf marginal withered orchard.In conclusion,the reason of apple leaf withered away could be deduce excessive sodium content in the soil of leaf withered orchard.