苹果树是需硼较多的果树,其叶片含硼量通常在25 PPm以上。据测,当土壤中水溶性硼的含量低于0.2～0.3 PPm时,就会出现许多缺硼症状。缺硼的苹果树,顶芽逐渐枯死,嫩叶上出现水渍状斑,叶片逐渐脱落,新梢停止生长。有的叶片变厚、发脆、退绿,中、短枝很难现花或花芽分化不良。 Apple trees are more need to boron fruit trees, the leaf boron content is usually above 25 PPm. It is reported that when the content of soluble boron in soil is less than 0.2 ~ 0.3 PPm, many boron deficiency symptoms occur. Boron-deficient apple trees, the top bud gradually withered, water stains spotted on the young leaves, leaves gradually fall off, the new shoots stop growing. Some leaves thicken, brittle hair, back green, spur, spur is difficult to spend flowers or poor bud differentiation.