氮素营养水平对大垄双行膜下滴灌玉米花粒期叶片衰老特性及产量的影响

Effects of nitrogen on leaf senescence and yield of maize under-mulch-drip irrigation in double lines at one width ridge

研究了氮素营养水平对大垄双行膜下滴灌玉米生育后期叶片衰老特性及产量的影响。结果表明:随着氮素施用水平的增加,玉米叶片叶绿素和可溶性蛋白含量、4种保护酶(SOD、POD、CAT和APX)活性均显著升高,MDA和H2O2含量与氧自由基产生速率则降低,当氮肥达到400 kg.hm-2,则呈现相反趋势。花后同一时期的同一氮肥处理下,玉米不同层位叶片叶绿素含量,可溶性蛋白含量,POD、CAT和APX活性从大到小依次为:穗位叶、穗位上第5片叶、穗位下第5片叶。玉米不同层位叶片SOD活性从大到小,开花初期(0～10 d)依次为:穗位叶、穗位上第5片叶、穗位下第5片叶;开花中后期依次为穗位上第5片叶、穗位叶、穗位下第5片叶。氮素营养水平和玉米叶片衰老及产量之间密切相关,应合理施肥,防止因氮素缺乏和过量引起的叶片早衰及产量降低。

The effects of different levels of nitrogen nutrition on leaf senescence and yield were studied under-mulch-drip irrigation. The results showed that the contents of chlorophyll and protein and the activities of protective enzymes（ SOD, POD, CAT and APX） were enhanced,and the contents of MDA, H2O2,O2 production rate decreased with the increase of nitrogen fertilizer. When 400 kg. hm-2 nitrogen application amounts was used, parameters mentioned above of leaves from different positions showed the opposite trend. Under the same nitrogen fertilizer level and stage, the sequence of chlorophyll and protein content, POD, CAT, APX activities was：ear leaf,5th leaf above ear,5th leaf below ear. From the flowering stage to 10 days, the order of SOD activity was ear leaf, 5th leaf above ear,5th leaf below ear. While the order was 5th leaf above ear,ear leaf,5th leaf below ear at later flowering stage. There was close relationship between leaf senescence, nitrogen nutrition and kernel yield. We should apply nitrogen reasonably, and lacking and excessive nitrogen could cause leaf senescence and yield reduction.