| Agricultural sciences |
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| Effects of seeding rates and nitrogen fertilizer managements on photosynthetic productivity and nitrogen utilization in direct-seeded rice |
| Jiang Mingjin, Ma Jun, Sun Yongjian, Yan Fengjun, Xu Hui, Yang Zhiyuan, Sun Jiawei |
| (Key Laboratory of Crop Physiology, Ecology, and Cultivation in Southwest China, Ministry of Agriculture/Rice Research Institute, Sichuan Agricultural University, Wenjiang 611130, Sichuan, China) |
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Abstract Due to the climatic feature of low light, small temperature difference and high humidity, transplanting rice was the major pattern in rice production in Sichuan Basin. As the rural labor force was decreased and the new types of rural management body were developing rapidly, the development of direct-seeded rice has becoming increasingly concerned. With the further development of direct seeding technology,direct seeding technique of rice has been successfully applied in 12 provinces and cities in China, which showed a significant role in improving the production and efficiency. In terms of the particular climate, topographic condition, and the hybrid rice in Sichuan Province, there were few studies on direct-seeded rice. Many researches had been done on the growth and development in direct-seeded rice under mechanical dry direct seeding and precision hill-direct-seeding, but the nitrogen management in those studies was according to the high-yield cultivation management of transplanting rice, and whether the nitrogen fertilizer management of transplanting rice was appropriate for direct-seeded rice was undefined. Seeding rate could immediate affect the population quality of rice plants and grain yield. The former researches often used the conventional rice as material but not the hybrid rice, so, further studies on the effects of seeding rate and nitrogen management on the dry matter production characteristic, nitrogen absorption and utilization law in direct-seeded hybrid rice were necessary.
Hybrid rice 446A/518 was used to investigate the effects of seeding rate and nitrogen fertilizer management on the photosynthetic productivity, dry matter accumulation and translocation, nitrogen absorption and utilization under manual wet direct-seeding,
and the correlation among the three which are photosynthesis index, grain yield and nitrogen utilization efficiency of rice plants were also taken to analyze. The results indicated that increasing the seeding rate would enhance the leaf area index during jointing stage and promote the nitrogen accumulation, nitrogen use efficiency (NUE) for biomass production and NUE for grain production. However, the leaf area index (LAI), SPAD value, photosynthetic rate, dry matter accumulation and translocation, partial factor productivity of applied nitrogen and NUE firstly increased and then decreased with the increasing of seeding rate. From the views of nitrogen management, the nitrogen fertilization for heading sprouting of 40% (N2) would obtain the highest LAI during jointing stage. Adding the nitrogen fertilization for heading sprouting was beneficial to increase LAI after heading stage and promote photosynthetic rate, dry matter accumulation and nitrogen accumulation, enhance substance accumulation and turn-over capacity and nitrogen-absorption and nitrogen utilization efficiency under the seeding rates of 15.0 or 22.5 kg/hm2. Moreover, when the seeding rate was added up to 30.0 kg/hm2, through antedisplacement of nitrogen would avail the nutrient absorbability of rice and promote substance accumulation and turn-over capacity and improve the NUE. Correlation analysis indicated that both the photosynthetic efficiency and LAI during heading stage were significantly correlated with grain yield, nitrogen-absorbing ability and nitrogen-utilizing efficiency of rice plants. In summary, when the seeding rate was 22.5 kg/hm2 and the ratio of nitrogen application at transplanting stage, tillering stage and booting stage were 40%, 10%, and 50%, respectively, it would lead to gain the relatively high grain yield and higher photosynthetic efficiency, dry matter production capacity and nitrogen utilization efficiency.
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Published: 20 September 2015
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播种量和氮肥运筹对直播杂交稻光合生产力及氮素利用的影响
在人工湿润直播条件下,以早熟杂交稻组合446A/518为试验材料,研究播种量和氮肥运筹对直播稻的光合特性、物质积累与转运和氮素吸收利用的影响,并探讨了光合指标与产量和氮素吸收利用效率的相关性。结果表明,增加播种量能提高拔节期叶面积指数,同时促进各时期氮素积累、氮素干物质生产效率及稻谷生产效率,但抽穗后叶面积指数、SPAD值、光合速率和水稻物质积累与转运能力、氮素偏生产力和氮素利用率则表现为先增加后降低。从氮肥运筹方式来看,拔节期叶面积指数均以氮素穗肥比例40%下最大。S1、S2播种量下增加氮素穗肥比例有利于提高抽穗后叶面积指数,促进光合速率、干物质积累量和氮素积累,提高物质积累与转运能力和氮素吸收利用效率。而播种量增大到30.0 kg/hm2时,氮肥适当前移更有利于水稻养分的吸收,并促进水稻物质积累与转运能力和提高氮肥利用率。相关分析表明,抽穗期光合作用速率和叶面积指数与产量和氮素吸收利用效率均表现为显著正相关。总之,播种量22.5 kg/hm2,以氮素基肥、蘖肥和穗肥分别占40%、10%和50%的运筹方式能获得最佳产量,且具备较高的光合作用效率、干物质生产效率及氮素利用效率,为本试验最佳处理。
关键词：
播种量,
氮肥运筹,
光合生产力,
氮素吸收,
氮素利用率
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