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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 incompatible contradiction between the growth period of double cropping rice and double cropping rice in the middle and lower reaches of the Yangtze River, two rice varieties, Zhongjiazao 17, which is a conventional early rice variety, 36.4, 28.6, 19.0 m-2) and nitrogen application rate (0, 110 ~ 140, 176 ~ 189 kg N hm-2) on the yield and nitrogen use efficiency of double cropping rice. The results showed that the “double cropping” rice-planting double cropping pattern was beneficial to the high yield in the early and second seasons, and the highest yield was obtained with the “high density + high nitrogen” treatment, reaching 16.94 t hm-2 in two years 16.99 t hm-2, but no significant difference with the “high density + low nitrogen” treatment. The nitrogen use efficiency decreased with the increase of nitrogen application rate, and increased with the increase of planting density. The highest treatment was 62.77%, 55.75%, 65.82% and 64.37% in 2 years and 4 quarters, respectively, which were 12.11%, 9.01%, 8.49% and 2.14% higher than that of “Gaomi + Compared with the treatment of ”low density and high nitrogen“, the dry matter accumulation and the radiation utilization rate of the population had certain advantages. This shows that in this mode, the appropriate increase in mechanical insertion density, reduce the amount of nitrogen, both to achieve high yield, but also significantly improve nitrogen utilization. Adopting the pattern of ”morning and evening", the combination of low nitrogen and close planting can be used as the key technology of double cropping double cropping rice in the middle and lower reaches of the Yangtze River.