幼穗分化期氮肥用量降低水稻遮光减产效应研究

Research of Panicle Nitrogen Fertilizer Amount on Reducing Yield Reduction Caused by Shading at Young Panicle Differentiation Stage of Rice

【目的】探讨水稻幼穗分化期氮肥用量对遮光导致的水稻减产效应的作用,为水稻遭遇寡照稳产栽培提供理论依据。【方法】以超级稻品种桂农占为试验材料,幼穗分化期氮肥用量0kg/hm^2(N0)、22.5kg/hm^2(N1)、37.5kg/hm^2(N2)和52.5kg/hm^2(N3)为主区,幼穗分化二期至成熟期不遮光(S0)、幼穗分化二期至齐穗期遮光(S1)、齐穗期至成熟期遮光(S2)、幼穗分化二期至成熟期遮光(S3)为副区,进行大田裂区试验,研究幼穗分化期氮肥不同用量与幼穗分化后不同遮光时间对水稻生育进程、茎蘖特征、产量及其构成的影响。【结果】不同氮肥水平下,水稻产量均表现为处理S0>S1>S2>S3。相较于S0,处理S1、S2和S3分别减产32.0%、52.7%、67.8%,且差异显著;增施氮肥降低了遮光导致的减产幅度,在S1、S2、S3处理下,处理N2和N3水稻产量较N1分别提高3.9%和4.3%、4.4%和6.8%、0.9%和3.1%;同时分析发现增施氮肥延长了遮光处理下水稻的籽粒灌浆期,减少了成穗率、有效穗数、实粒数和千粒重的降低幅度。【结论】增施穗肥氮素用量可延长幼穗分化期后遭遇寡照水稻的籽粒灌浆期,降低遮光对水稻产量及构成因素的影响,在一定程度上降低遮光导致的水稻减产效应。其中增施氮肥对S2处理的稳产效果最好,其次为S1。

【Objective】Theoretical basis for stable yield cultivation of rice under shading environment will be provided based on the exploration of the effect of panicle nitrogen(N)fertilizer application on rice yield reduction caused by shading environment at young panicle differentiation stage.【Method】The Guinongzhan,a super rice variety of Guangdong province,was selected as test material to conduct split plot experiment.At second young panicle differentiation stage,four different panicle N fertilizer applications of 0 kg/hm^2(N0),22.5 kg/hm^2(N1),37.5 kg/hm^2(N2),52.5 kg/hm^2(N3)were set as main part.Four shading treatments were set as the secondary part:not shading from the second young panicle differentiation stage to maturity(S0),shading from the second young panicle differentiation stage to full heading stage(S1),shading from full heading stage to maturity(S2),and shading from the second young panicle differentiation stage to maturity(S3).The effects of different N fertilizer amount at second young panicle differentiation stage and different shading time after the young spike differentiation on rice growing process,stem tiller characteristics,yield and its components were studied.【Result】Under different N fertilizer application amount,yields all showed as:S0>S1>S2>S3.Compared with S0,yields of S1,S2 and S3 significantly decreased 32.0%,52.7%and 67.8%,respectively.The increment of N fertilizer reduced the yield reduction effect resulted by shading.Compared with N1,yields of N2 and N3 under S1,S2 and S3 increased 3.9%and 4.3%,4.4%and 6.8%,0.9%and 3.1%,respectively.Meanwhile,the increment of N fertilizer prolonged grain filling stage,decreased the reduction range of spike rate,effective panicle number,filled grains and 1000-grain weight.【Conclusion】The increasing application of panicle N fertilizer application could prolong the grain-filling of rice young panicle differentiation stage encountered low light,and reduce the effect of shading on yield and its components,which decreased the yield reduction extent caused by shading.The increasing application of N fertilizer had the best effect on the stable production of rice in S2,and then followed by S1 treatment.