麦-稻轮作系统中小麦施氮水平对后季直播水稻产量和氮肥利用效率的影响

【目的】研究华中地区麦—稻轮作系统中小麦季不同施氮水平对后季直播水稻生长发育、产量和氮肥利用效率的影响,探讨此系统中最佳的氮肥管理模式,为制定合理的氮肥管理方案提供理论依据和技术支持。【方法】采用裂区设计,主处理为小麦季3个不同氮处理(施N 0、105和210 kg/ha,分别记作WN0、WN105和WN210),副处理为后季水稻3个不同氮处理(施N 0、90和180 kg/ha,分别记作RN0、RN90和RN180),测定小麦和水稻不同生育期的株高、分蘖数、叶面积指数和生物量等指标,成熟期测定产量、产量构成因子及秸秆和籽粒氮含量。【结果】与其他施氮量相比,麦季施氮210 kg/ha对后季直播水稻的株高、分蘖数、生物量、产量和氮肥利用效率均有明显影响,其中WN210RN90处理的各项指标均较高,整体表现较好。在麦稻季均施氮的情况下,系统周年产量表现为WN210RN180>WN105RN180>WN210RN90>WN105RN90,前3个处理的系统周年产量均在13.50 kg/ha以上;结合小麦产量来看,WN210RN180和WN210RN90处理(3.55 t/ha)高于WN105RN180处理(2.79 t/ha)。【结论】小麦—直播水稻轮作系统中水稻生长季应充分考虑前季小麦的氮肥后效,适当降低后季直播水稻的施氮量。综合考虑产量和氮肥利用效率,麦季210 kg/ha和稻季90 kg/ha的施氮组合(WN210RN90)为华中地区小麦—直播水稻轮作系统的最佳氮肥管理模式。

Effects of N application rates on grain yield and N-fertilizer utilization efficiency of succeeding direct-seeded rice in wheat-rice rotation system

Objective]The present study was conducted to investigate effects of N application rates in wheat growing season on growth, grain yield and N-fertilizer utilization efficiency(NUE) of succeeding direct-seeded rice, in order to explore the optimal mode of N management in a wheat-rice rotation system in central China. Method]Split block design was employed with three N application rates(0, 105 and 210 kg/ha, expressed as WN0, WN105, and WN210, respectively) in wheat growing season, and after harvest of wheat, each plot was divided equally into three small plots which were assigned to three N application rates(0, 90, and 180 kg/ha, expressed as RN0, RN90, and RN180, respectively) in succeeding rice season. Plant height, tiller number, leaf area index, aboveground biomass, grain yields and yield components of wheat and rice were recorded at different growth stages, respectively. N contents of straw and grain of wheat and rice at maturity stage were determined, respectively. Result]The results showed that, N application at 210 kg/ha in wheat growing sea-son had significant influence on plant height, tiller number, aboveground biomass, grain yield and NUE of succeeding di-rect-seeded rice compared with other N application rates. Among all treatments, every index for WN210RN90 was higher, and overall the performance under WN210RN90 was better. When N was applied in both wheat and rice growing seasons, all treat-ments was ranked in order of total grain yield: WN210RN180>WN105RN180>WN210RN90>WN105RN90, especially total grain yield of system under WN210RN180, WN105RN180 or WN210RN90 was over 13.50 kg/ha. In view of wheat grain yield, WN210RN180 and WN210RN90(3.55 t/ha) were better than WN105RN180(2.79 t/ha). Conclusion]N-fertilizer application in wheat growing season have a significant residual effect to the succeeding rice season. Therefore, in wheat-rice rotation system, N application rate in rice growing season should be reduced due to residual N-fertilizer effect of wheat season. Considering grain yield and NUE in both rice and wheat seasons, the recommended N application rates(WN210RN90) are 210 kg/ha in wheat season and 90 kg/ha in rice season in central China, this N application combination is optimal mode of N management in rice-wheat rotation system.