不同锌水平果园苹果树锌含量的年周期变化动态

【目的】研究大田条件下不同锌水平果园苹果树体锌吸收运转分配和锌运转系数的周年变化,解释不同锌水平果园苹果树锌含量的周年变化规律。【方法】以盛果期‘红富士/平邑甜茶’苹果为试材,测定缺锌小叶病树和正常树周年内不同物候期土壤及树体各器官的锌含量。【结果】不同锌水平树体根系锌含量周年动态变化差异显著,正常树锌含量周年内基本处于稳定水平,而病树根系前期呈下降趋势,后期急剧上升;在多年生枝条中,正常树锌含量始终处于较高水平,且后期有所增加,而病树在生长发育后期锌含量显著降低;新生器官的锌含量变化趋势基本一致,但正常树的锌含量始终高于病树。【结论】小叶病树生长发育后期锌低位贮藏引起地上部/根锌的运转系数低、树体锌含量上运受阻,同时,缺锌改变了树体养分吸收的节奏,致使小叶病苹果树春夏根系供锌能力低,形成了生长发育后期锌在根系贮藏、上运困难的特有锌运转规律。

Annual Dynamics of Zinc Contents in Apple Trees Under Different Zinc Levels of Apple Orchard

Objective] In order to explain the dynamic changes of absorption and transportation of zinc in apple tree with different zinc content level of apple orchard, the annual regularity of distribution and transportation of zinc nutrition was studied.Method] Zinc concentration in soil and organs from apple cultivar 'Fuji' with rootstock M. hupehensis Rehd in the diseased apple tree (lack zinc) and the normal apple tree were determined at different stages. Result] The concentration and the annual regularity of soil zinc nutrition in both diseased apple tree (lack zinc) and normal apple tree was consistent, but the content of zinc in 20-40 cm layer of diseased tree was lower than that of normal tree. The difference of root zinc concentration between diseased and normal tree was significant, the root of diseased trees showed a rise-and-fall motif, but in normal tree it kept higher level. The content of zinc in perennial shoots of normal tree kept high level, and increased in later period of development, but the diseased tree showed an inverse tendency. The tendency of the changes of zinc concentration in new organs under different zinc levels were similar in general, but the concentration of zinc in normal trees exhibited more than that of diseased trees. Conclusion] The lower content of available zinc in the layer where the apple tree roots concentrated was the main reason for the diseased trees (lack zinc), besides, the diseased trees resulted in the lower transportation index of upward/roots of zinc induced by zinc restoration in the lower position in later period of development and the inhibition of zinc uptake of apple trees. Meanwhile, Zn-deficiency disturbed the rhythm of zinc absorption of trees and resulted in that the diseased trees formed specific zinc translocation regularity, i.e. the zinc supplying ability of roots was low in spring and summer and had difficulty to uptake zinc while large amount of zinc was restored in roots in the later period of development.