捷克斯洛伐克园艺学家对苹果树的养分状况进行了系统的研究,Hudska等发现,苹果产量与去年的叶片含钾量呈正相关,而和氮与钾的比率呈负相关。当金冠、Lord Lambourne和Belle de Boskoop苹果叶片中的氮与钾比率分别为1.5—1.8,1.5—2.0和1.3—2.0时产量最高;当氮与钾比率为1.9—2.1,2.0—2.5和2.0—2.3时产量最低。研究结果认为,适宜的叶片营养含量是:氮2.5%,磷0.25%,钾1.75%, Horticultural scientists in Czechoslovakia systematically studied the nutrient status of apple trees. Hudska et al. Found that apple production was positively correlated with last year’s potassium content and negatively correlated with the ratio of nitrogen to potassium. When the ratio of nitrogen to potassium in Golden Delicious, Lord Lambourne and Belle de Boskoop apple leaves was 1.5-1.8, 1.5-2.0 and 1.3-2.0 respectively, the highest yield was obtained. When the ratio of nitrogen to potassium was 1.9-2.1, 2.0-2.5 and 2.0- 2.3 when the lowest yield. The results showed that the optimum nutrition content of leaves was 2.5% nitrogen, 0.25% phosphorus, 1.75% potassium,