机插条件下低氮密植栽培对“早晚兼用”双季稻产量和氮素吸收利用的影响

Effect of Low Nitrogen Rate Combined with High Plant Density on Yield and Nitrogen Use Efficiency of Machine-transplanted Early-late Season Double Cropping Rice

为了缓解长江中下游双季稻区机插双季稻生育期不配套的矛盾,2014—2015年早晚两季均以常规早稻品种中嘉早17为材料,在大田栽培条件下研究机插密度（36.4、28.6、19.0穴m–2）与施氮量（0、110~140、176~189 kg N hm–2）对机插双季稻产量及氮肥利用率的影响。结果表明：采用＂早晚兼用＂机插双季稻栽培模式有利于早、晚2季周年高产,以＂高密＋高氮＂处理产量最高,2年分别达到16.94 t hm–2和16.99 t hm–2,但与＂高密＋低氮＂处理的产量差异不显著;氮肥利用率随氮肥用量增加而下降,随栽插密度增加而提高,以＂高密＋低氮＂处理最高,2年4季分别为62.77%、55.75%、65.82%、64.37%,比＂高密＋高氮＂处理分别提高12.11%、9.01%、8.49%、2.14%;＂高密＋低氮＂处理与＂低密＋高氮＂处理相比,群体干物质积累量及辐射利用率均有一定的优势。由此可见,在此模式下适当增加机插密度,减少氮肥用量,既可实现高产,又能显著提高氮素利用率。采用＂早晚兼用＂品种搭配模式,低氮、密植栽培可作为长江中下游双季稻区机插双季稻生产的关键技术。

In order to alleviate the contradictions of growth period mating problem of machine-transplanted double cropping rice in Changjiang Rive regions, a field experiment with three nitrogen rates（0, 110–140, and 176–189 kg N ha–1） and three plant densities（36.4, 28.6, and 19.0 hill m–2） was conducted using conventional early variety ＂Zhongjiazao 17＂ in both early and late seasons to explore the effects of machine transplanting densities and N application on yield and N recovery efficiency（REN） in 2014–2015. Adopting the same conventional early variety was able to reach the high yield in machine-transplanted early-late season double cropping rice. The treatment of high density（36.4 hills m–2） with high nitrogen rate（176 kg ha–1 in early season, 189 kg ha–1 in late season） had the highest yield of 16.94 t ha–1 in 2014 and 16.99 t ha–1 in 2015, but not significantly higher than the treatment of high density with low nitrogen rate（110 kg ha–1 in early season, 140 kg ha–1 in late season）. REN declined with increasing N application and improved with increasing density. The treatment of high density with low nitrogen rate showed the highest REN of 62.77%, 55.75%, 65.82%, 64.37% in early and later season 2014 and 2015, which are 12.11%, 9.01%, 8.49%, and 2.14% higher than the treatment of high density with high nitrogen rate, respectively. The treatment of high density with low nitrogen rate displayed certain advantages of dry matter accumulation and radiation use efficiency compared with the treatment of low density（19.0 hills m–2） with high nitrogen rate. As a result, adopting high planting density and low nitrogen fertilizer could not only achieve high yield, but also significantly improve REN in early-late season double cropping rice. The key technology provided in the study would be available for machine-transplanted double cropping rice cultivation in the Yangtze River regions.