氮肥后移和栽插规格对华南晚稻产量和氮肥利用率的影响

Grain Yield and Nitrogen Use Efficiency of Late-cropping Rice in Response to Delayed Application of Nitrogen and Altered Plant Spacing in South China

【目的】通过氮肥减量后移和改变栽插规格,进一步提高水稻产量和氮肥利用率。【方法】两年晚季,设置不施氮肥(T1)、习惯施肥(对照,T2)、3个中度氮肥后移(T3~T5)和3个重度氮肥后移并减量(T6~T8)8个处理,T3~T8包含施氮量、种植密度和栽插规格的变化。【结果】与T2处理相比,T3~T5处理平均产量两年分别增产29.7%和15.9%,T6~T8处理分别增产26.4%和18.6%。T3~T5和T6~T8处理氮素吸收和生长速率在穗分化前比T2更少或缓慢,此后则大幅增加或加快。两年均值,T3~T5和T6~T8处理抽穗期平均叶面积指数比T2处理分别提高8.5%和11.8%,抽穗期叶片含氮量分别提高16.8%和23.5%;每公顷穗数分别增加14.5%和15.2%,穗大小持平或增加12.5%,库容分别扩大13.6%和29.3%,结实率提高9.0%或持平,千粒重持平或下降9.0%,生物学产量分别增加14.8%和15.5%,收获指数分别提高7.2%和6.4%;氮素吸收总量分别增加27.6%和40.7%,氮肥吸收利用率分别提高85.9%和124.2%,氮肥农学利用率分别提高99.1%和102.5%,氮肥偏肥生产力分别提高32.1%和36.2%。增施氮肥、增密和改变栽插规格对产量和氮肥利用率的影响不大。与中度氮肥后移处理相比,重度氮肥后移处理的库容扩大13.5%并进一步提高了氮肥利用率,但未能再提高产量。【结论】在氮肥减量的情况下,中度和重度氮肥后移均使水稻的源和库显著扩大,产量和氮肥利用率显著提高。

【Objective】In order to further enhance grain yield of rice and nitrogen(N)use efficiency(NUE),N fertilizer was reduced and topdressing was delayed,together with alteration in row and plant spacing and planting density.【Method】In two late seasons,comparison trials were conducted with 8 treatments,including zero applied N(T1),farmers’practice(T2,control),3 moderately-delayed N topdressing(T3-T5)and 3 highly-delayed N topdressing(T5-T8).T3-T8 also had alteration in N application rate,planting density and row and plant spacing.【Result】In comparison to T2,the average grain yields under T3-T5 were increased by 29.7%and 15.9%,and those of T6-T8 were increased by 26.4%and 18.6%in two late seasons,respectively.In both late seasons,nitrogen uptake and plant growth under T3-T5 and T6-T8 were slower before panicle initiation and they were both increased or accelerated thereafter.Based on average results in two late seasons,leaf area indexes at heading stage were enhanced by 8.5%and 11.8%respectively under T3-T5 and T6-T8 compared with that under T2.Leaf nitrogen contents at heading stage were enhanced by 16.8%and 23.5%,respectively.The numbers of panicles per hectare were increased by 14.5%and 15.2%,panicle size remained unchanged or was increased by 12.5%,sink sizes were increased by 13.6%and 29.3%,seed setting rate was enhanced by 9.0%or remained the same,1000-grain weight remained identical or was decreased by 9.0%,biomasses were increased by 14.8%and 15.5%,and harvest indexes were increased by 7.2%and 6.4%,respectively.The total amounts of N uptake were increased by 27.6%and 40.7%,N uptake efficiencies were increased by 85.9%and 124.2%,agronomical efficiencies were increased by 99.1%and 102.5%,and partial factor productivity was increased by 32.1%and 36.2%,respectively.Additional N input,dense planting and alteration in row and plant spacing had little effect on yield and NUE.Highly-delayed N topdressing could further expand sink size and improve NUE,but could not enhance grain yield anymore.【Conclusion】With reduced N input,both source and sink of rice were substantially enlarged,and the yield and NUE were dramatically increased under moderately-delayed and highly-delayed N topdressing.