钾对大白菜的营养作用及其生理机制研究

STUDY ON K-NUTRITION OF CHINESE CABBAGE AND ITS PHYSIOLOGICAL MECHANISM

通过砂培试验和田间试验探讨了钾对大白菜的营养作用及其生理机制。砂培试验结果表明，钾能通过促进大白菜根系的生长、提高根系的脱氢酶活性和叶片的硝酸还原酶活性；增加对氮磷等养分的吸收，改善植株体内的氮磷钾营养状况；提高叶绿素含量，增加气孔导度和蒸腾强度，提高净光合作用速率，增加干物质的积累。田间试验得出，钾能在提高大白菜内源激素（玉米素、生长素和脱落酸）整体水平的同时，调节其平衡。主要表现在玉米素／脱落酸和生长素／脱落酸比值的降低，从而有利于叶球的形成。

This paper deals with the K-nutrition for chinese cabbage and its physiological mechanism. The results from sandy culture experiment indicated that K supply can enhance both the contents and the amounts of N. P in chinese cabbage by promoting root growth, activity of dehydrogenase in root and activity of nitrate reductaes in leaf,and increasing dry matter production by enhancing Chl. content and promoting stomatal conductance (CS). transpiration rate (TR), net photosynthesis rate (PN) as well as transplration efficiency. And from the field experiment, it can be obtained that K fertilization increase the levels of endogenous phytohormones in chinese cabbage as well as regulate their balance as decreasing the ratios of ZT/ABA and IAA/ABA, which is functional for head production.The experimental results also indicated that potash sulphate affects on these physiological mechanisms more efficiently than potash chloride does, which is the reason why chinese cabbage can yield more with potash sulphate applied at the adequately-high rates of K fertilization.