施氮量对水稻源库协同衰老特征的影响

Effects of nitrogen application on the synergistic senescence of rice source and sink

为探究施氮量对水稻源库器官协同衰老的影响及其生理机制,本试验测定了不同氮肥水平下水稻结实期天数、全生育期天数、叶面积指数(LAI)、叶片SPAD值、籽粒灌浆特性、叶片与籽粒的抗氧化酶活性[超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)]和丙二醛(MDA)含量。结果表明,2019—2020年,高氮水平(345 kg·hm;)下水稻的结实期和全生育期分别比低氮水平延长13.3~16.3 d和16.0~18.7 d, LAI、叶片SPAD值和籽粒灌浆活跃期较高,而叶面积衰减率较低。高氮水平的水稻剑叶和籽粒中的抗氧化酶活性均显著较高,而膜质过氧化产物MDA含量显著较低。相关性分析表明水稻施氮量与抽穗后叶片和籽粒不同生育阶段的抗氧化酶活性呈正相关,而与MDA含量呈负相关。综上所述,高氮水平下水稻源库的抗氧化酶系统酶活性较强,能减少MDA的积累,提高叶片持绿天数和籽粒灌浆活跃期,从而延缓了水稻源库协同衰老进程。

In order to explore the effect of nitrogen application rate on the synergistic senescence of rice source and sink organs and its physiological mechanism, the grain filling period, growth period, leaf area index(LAI), leaf SPAD value, grain filling characteristics, antioxidant enzyme activities [superoxide dismutase(SOD), peroxidase(POD), catalase(CAT)] and malondialdehyde(MDA) contents of leaves and grains under different nitrogen application rate were measured. The results showed that from 2019 to 2020, the grain filling period and whole growth period under high nitrogen levels were 13.3–16.3 d and 16.0–18.7 d higher than those under low nitrogen levels, respectively. Under high nitrogen level, the LAI,leaf SPAD value and active grain filling period were higher, and the leaf area attenuation rate was lower.Compared with CK, the activities of antioxidant enzymes in flag leaves and grains under high nitrogen level were significantly higher, and MDA content was significantly lower. Correlation analysis showed that the nitrogen application rate was positively correlated with antioxidant enzyme activities of leaves and grains,and negatively correlated with MDA content. In all, under high nitrogen level, the activities of antioxidant enzymes in rice source and sink organs were higher, which reduced the accumulation of MDA, promoted the leaves stay-green and prolonged the active period of grain filling, thus delaying the synergistic senescence process of rice source and sink.