机械化播栽对杂交稻氮素积累分配及碳氮比的影响

【目的】氮素吸收与积累是水稻产量形成的重要基础。随着农村劳动力转移，我国水稻生产机械化的步伐随之加快, 机械化播栽使杂交籼稻的生长发育和各生育阶段所处环境发生了改变，但针对其氮素吸收利用特性的研究还较少。本文以杂交籼稻F优498为材料，探讨机械化播栽条件下杂交稻的氮素积累、 分配及碳氮比特点。【方法】采用二因素裂区设计，主因素为播栽方式，共3个水平，分别为机械精量穴直播、 机插和常规手插；副因素为穴苗数，设2个水平，分别为低穴苗数和高穴苗数。研究播栽方式和穴苗数对杂交稻氮素积累、 分配及碳氮比的影响。【结果】机械化播栽对杂交稻氮素吸收利用及碳氮比产生了明显影响，与常规手插相比，机械精量穴直播显著提高了水稻拔节期和成熟期植株含氮量，同时提高了成熟期植株氮素积累能力。机插植株含氮量在抽穗期显著高于手插，并能在拔节期保持较高的植株氮素积累量。不同播栽方式叶片和茎鞘氮素转运量、 氮素表观转运率以及氮素转运贡献率、 氮素干物质生产效率和氮素偏生力表现为常规手插＞机插＞机械精量穴直播，而穗部氮素增加量和百千克籽粒吸氮量则为机械精量穴直播＞常规手插＞机插，氮素稻谷生产效率和氮素收获指数表现为机插＞常规手插＞机械精量穴直播。水稻植株全碳含量及植株碳氮比在各主要生育时期内均受播栽方式显著或极显著影响。机械化播栽方式配合低穴苗数能加强成熟期各器官碳氮比，配合高穴苗数处理能显著提高杂交稻抽穗期穗碳氮比，并且能够促进碳素在植株内的转化和分配。【结论】机械化播栽方式虽降低了拔节期植株全碳含量及植株碳氮比，但可显著提高水稻拔节期和成熟期植株含氮量，提高成熟期植株氮素积累能力，有利于杂交稻氮素高效吸收利用和植株体内碳氮代谢的平衡，因而获得高产高效。

Influences of mechanical sowing and transplanting on nitrogen accumulation,distribution and C/N of hybrid rice cultivars

【Objectives】The nitrogen uptake and accumulation are an important foundation for yield formation in rice. Along with the transfer of rural labor to the cities, the pace of rice production mechanization in China consequently grows rapidly. The growth, development, and the environment of each growth stage of hybrid rice have changed in the mechanical sowing and transplanting methods. However, less research has been done on how the mechanical sowing and transplanting methods influence the nitrogen absorption and utilization characterization. The hybrid indica rice (F you 498) is used in the experiments to explore the characteristics of nitrogen uptake, utilization and C/N. 【Methods】Two factorial split\|plot designs with three replications were used in this experiment, the main plots consisted of three sowing and transplanting methods (mechanical direct seeding, mechanical transplanting, and artificial transplanting), the subplots were subjected two seeding number per hill (low seeding number per hill and high seeding number per hill). The effects of sowing and transplanting methods and seedling number per hill on nitrogen accumulation, distribution and C/N were investigated. 【Results】Mechanical sowing and transplanting methods had apparent effects on the nitrogen uptake, utilization, and C/N of hybrid rice. The mechanical direct seeding improved the nitrogen content at the jointing and maturity periods, and the capabilities of nitrogen accumulation in plants of rice at the maturity period. The nitrogen content at the heading period in the mechanical transplanting was higher than the artificial transplanting, the mechanical transplanting could keep high nitrogen accumulation of rice at the jointing period. The nitrogen translocation, apparent nitrogen translocation rate of rice leaves and stem\|sheath, nitrogen transfer rate, nitrogen use efficiency for biomass and partial factor productivity of applied nitrogen in artificial transplanting were higher than those in mechanical transplanting and the lowest in mechanical direct seeding. However, the N increase in panicle and nitrogen uptake per 100 kg of grain under different sowing and transplanting methods were different, mechanical direct seeding was the highest, followed by artificial transplanting and mechanical transplanting. Furthermore, the nitrogen use efficiency for grain production and nitrogen harvest index in mechanical transplanting were higher than those in artificial transplanting, and the lowest in mechanical direct seeding. The carbohydrate content, C/N of plant in hybrid rice at the jointing, heading, and maturity periods were significantly influenced by different sowing and transplanting methods. The mechanical sowing and transplanting methods cooperate with low seedling number per hill could enhance the C/N of different organs at the maturity period. The C/N of panicles of hybrid rice cultivar is significantly increased under the mechanical sowing and transplanting methods cooperate with high seedling number per hill, subsequently improved the carbohydrate transformation and distribution in plant. 【Conclusions】The characteristics of nitrogen accumulation and utilization of hybrid rice under different mechanical sowing and transplanting methods are different. Mechanical direct sowing and transplanting methods plus lower seedling number per hill are effective way in control and regulation of the nitrogen uptake and transfer in rice, keeping a relative high N accumulation during the whole growing period of rice, thus leading to a high N requirement for 100 kg of grain production and high yield.