抽穗期施氮肥对延缓小麦旗叶衰老的机理初探

抽穗期施氮肥可提高小麦旗叶的光合速率、全氮与Rubisco的含量,而蛋白水解酶活力则下降。在小麦旗叶光合功能可逆衰退阶段,叶片全氮、Rubisco的15N丰度均处于高水平,莱州953小麦旗叶全氮、Rubisco的15N丰度分别从0.998降至0.651和1.432降至0.470,扬麦5号旗叶中全氮、Rubisco的15N丰度分别从0.896降至0.485和1.243降至0.511,表明Rubisco仍处于动态的降解、合成这一周转过程中,仍有大量的Rubisco重新合成;而在光合功能不可逆衰退阶段,叶片全氮、Rubisco的15N丰度均处于低水平,全氮、Rubisco的15N丰度分别维持在近对照水平,且基本无变化,表明此时无Rubisco的重新合成;同时也说明小麦植株在生育后期仍有较高的吸收、利用氮素的能力。

A PRELIMINARY INVESTIGATION ON SENESCENCE MECHANISM OF FLAY LEAF BY NITROGEN FERTILIZER IN EARING PERIOD

Applying nitrogen fertilizer in earing period could enhance net photosynthetic rate,content of total nitrogen,content of Rubisco,while could decline the proteases activity.During the relative active photosynthetic duration(RAPD) of wheat flag leaf,~(15)N abundance of total nitrogen and Rubisco were at the high level.~(15)N abundance of total nitrogen of Laizhou953 decreased from 0.998 to 0.651,while~(15)N abundance of Rubisco was from 1.432 to 0.470;~(15)N abundance of total nitrogen of Yangmai No5 was from 0.896 to 0.485 while~(15)N abundance of Rubisco is from 1.243 to 0.511.During the Rapid Photosynthetic Duration(RPD) of wheat flag leaf,they were at a lower level(~(15)N abundance of total nitrogen and Rubisco were near the control sample level),and had little changes.All these indicated that there were a large number Rubisco re-synthestized during RAPD,but there was little Rubisco re-synthesized during RPD.These also illustrated that wheat had higher ability on absorbing and utilizing nitrogen during later stage of wheat growth.