红富士苹果树小叶病与营养条件的关系

Relationships Between Little Leaf and Nutrient Condition of Fuji Apple Trees

测定了苹果国土壤、树体中的Ｚｎ和有关养分的含量，结果表明：２０个正常果园土壤有效Ｚｎ的平均含量为３．７ｍｇ·ｋｇ－１，１０个小叶病果园的土壤有效Ｚｎ低于１ｍｇ．ｋｇ－１．小叶病果树枝、叶中Ｚｎ的含量显著低于正常树，根中则相反．小叶病果树枝、叶中的Ｐ／Ｚｎ、Ｋ／Ｚｎ和Ｆｅ／Ｚｎ显著高于正常树，病叶中的Ｐ／Ｚｎ＞１００，正常树叶的Ｐ／Ｚｎ＜１００．由此认为，除土壤有效Ｚｎ不足外，根中的Ｚｎ向地上部分运输受阻和营养元素间的不平衡，也是小叶病发生的重要原因。

The contents of Zn and other nutrients in soil and trees Of orchards were measured. The results showed that in 20 orchards without little leaf the means of soil availible Zn was 3.7 mg.kg-1; in 10 orchards with little leaf it was below 1 mg. kg-1. The Zn contents in branches and leaves of trees with little leaf was significantly lOwer than that in trees without little leaf,and the reverse was true for Zn in roots, P/Zn, K/Zn and Fe/Zn in branches and leaves of trees with little leaf were significantly higher than that in trees without little leaf,and P/Zn in trees with little leaf was higher than 100. in trees without little leaf it was below 100. Therefore,it was conolided that except low availible Zn in soil,retardation of Zn transportation to upper part of tree and nutrient imbalance in tree were the couses of occurence of little leaf.