施氮量和栽培模式对旱地冬小麦旗叶衰老及其活性氧代谢的影响

以冬小麦小偃22为试验材料,研究3种栽培模式(常规栽培、覆草栽培、地膜覆盖)和3种施氮水平(施纯氮0、120和240 kg/hm2)下旗叶衰老与活性氧代谢特性.结果表明,与常规栽培(CK)相比较,覆草栽培条件下叶绿素含量始终较高(P<0.05),叶片衰老速度缓慢,代谢强度旺盛,有利于籽粒灌浆和光合产物的积累,产量显著增加(P<0.05).在灌浆前期,地膜覆盖条件下叶片叶绿素含量增加(P<0.05),叶片保护性酶活性(POD、CAT)提高,膜脂过氧化程度低;但在灌浆后期,叶绿素含量急剧下降,叶片衰老速度加快,膜脂过氧化程度加剧,产量仍显著增加(P<0.05).施用氮肥在一定范围内可提高旗叶叶绿素含量和保护性酶活性(POD、CAT),降低膜脂过氧化程度;施氮量为120 kg/hm2时,冬小麦旗叶叶绿素含量最高,叶片衰老迟缓,代谢强度降低缓慢,膜脂过氧化程度低,有利于小麦后期生长和籽粒灌浆,在3种栽培模式下产量均最高.

Winter Wheat Flag Leaf Aging and Reactive Oxygen Species Metabolism under Different Nitrogen and Cultivation Modes in Dryland

The experiment was carried out to study the effects of three cultivation modes(flat planting,straw mulching,plastic sheet-mulching) and three different N levels(without nitrogen,120 N kg/hm2 and 240 N kg/hm2) on flag leaf aging of the winter wheat cultivar 'Xiaoyan 22'.The results showed that compared with flat planting(CK),straw mulching could increase the chlorophyll content of flag leaf(P<0.05),slow the speed of flag leaf aging and the extent of declining metabolizability,increase the yield(P<0.05).At the early filling stage,plastic sheet-mulching could increase the chlorophyll content of flag leaf,enhance POD,CAT activities,and lower malondialdehyde(MDA) content.At the late filling stage,there were a remarkable decline of leaf chlorophyll content,a quick leaf aging and a marked increase of MDA.Plastic sheet-mulching could increase the yield(P<0.05).Nitrogen could enhance the chlorophyll content of flag leaf and the extent of active oxygen(POD,CAT),lower malondialdehyde(MDA) content.When the nitrogen was 120 N kg/hm2,the chlorophyll content of flag leaf was the most highest,the speed of flag leaf aging was slow,the extent of declining metabolizability was slow too.It is was of great benefit to wheat growth and filling at the late filling stage.