施氮水平对不同栽培模式小麦旗叶衰老及产量的影响

Effect of Nitrogen Application on Senescence of Flag Leaf and Grain Yield in Wheat in Different Planting Models

氮素水平与小麦后期旗叶衰老有着密切关系。中氮和高氮处理与低氮和无氮处理相比,显著提高了SOD和POD的活性,相对改善了细胞中活性氧产生与清除之间的平衡,减少了细胞内过氧化物的积累,减缓了叶片衰老;但平作栽培小麦264kg/hm2水平(N3处理)与165kg/hm2水平(N2处理)间的SOD、POD活性、MDA含量以及叶绿素含量等生理指标差异不显著,表明施氮量达到一定水平后继续增加施氮量对延缓小麦旗叶衰老无显著效应。通过对垄作和平作2种栽培模式的比较发现,小麦旗叶衰老进程分为两个阶段;平作小麦以花后14天,垄作小麦以花后21天为拐点,前期为缓慢衰老期,后期为急剧衰老期。在缓慢衰老期,旗叶POD、SOD活性,叶绿素含量会略有上升;而进入急剧衰老期后,上述3个生理指标都急剧下降。平作小麦比垄作小麦提前进入急剧衰老期。氮素水平为165kg/hm2时,2种栽培模式均可以获得中产以上产量;264kg/hm2水平下能够获得更高的产量,且垄作栽培小麦的增产优势较平作小麦更明显。

There is a close relation between nitrogen nutrition and senescence of wheat flag leaf. Treatment N3 （264kg ha-1） and N2 （165kg ha-1） remarkably increased the activity of SOD and POD compared with treatment N0, improved the balance of reactive oxygen production and scavenging, reduced the accumulation of peroxide in cells, and thus slowing down the processes of flag leaf senescence. No remarked differences in the activities of SOD and POD, MDA content and chlorophll content were observed between treatment N3 and N2, indicating that when the nitrogen application amount rose to a reasonable level, the flag leaf senescence can not be slowed down by continuous increase of nitrogen application. The process of senescence could be divided into two periods, i.e. slow-senescence phases and fast-senescence phases. In slow-senescence phases, the activities of POD and SOD, MDA content and chlorophll content in flag leaf increased slightly. At fast-senescence phases, the three physiological parameters decreased sharply, and the wheat showed obvious senescence characteristics. The inflection point of flag leaf senescence is 14 days after anthesis with flat planting and 21 days after anthesis with raised bed planting. When 165 kg ha-1 of nitrogen applied, middle yield to higher yield can be obtained with the both planting models . On condition of nitrogen nutrition level 264 kg ha-1, the grain yield of 7845.7 kg ha-1 was achieved in raised bed planting, 9.6 % higher than that in flat planting.