观察苹果树不同枝龄的树皮切片,发现未曾形成落皮层的部位树皮韧皮纤维束的层数和枝龄是一致的,为观察树皮组织结构变化,提供了发育解剖学依据。探明在树皮衰老过程中,新周皮下面树皮组织中韧皮射线外端开始弯曲和结构消失的年份与树体发生腐烂病的轻重存在明显的相关性,经统计分析,提出了"壮树"的初步标准,经检查验证,结果一致。试验证明,对衰老部位的树皮人为更新,可取得防病保树的效果。

An invastigation on the relation between bark senescing process and susceptibility to Valsa invasion was conducted. The number of circles of phloem fiber bundles is corresponding to the age of apple, bark growth. During the senescing process of bark, the disturbance and disorganization of the end part of phloem rays in the outer old bark tissues is closely related to susceptible performance of the bark. Characteristic standard of "strong tree" was suggested and verified in field trials. Artificial renewal of senescent bark was helpful for enhancing resistance to fungal invasion and therefore prevention of disease incidence.