氮肥缓速配施对机插杂交稻氮素利用特征的影响

【目的】探索在西南稻区,钵苗机插和氮肥缓速配施能否发挥杂交籼稻的大穗优势获得高产,以及钵苗机插杂交稻在氮肥缓速配施下的氮素吸收利用特征,为我国杂交水稻育插秧节肥丰产技术的应用提供理论和实践依据。【方法】本试验采用二因素裂区设计,主区为钵苗机插和毯苗机插2种机插方式,分别记为M₁和M₂;副区为4种氮肥管理模式,分别是N₁（100%缓释肥一次基施）,N₂（70%缓释肥+30%尿素一次基施（缓速基施））和N₃（70%缓释肥做基肥+30%尿素做穗肥（缓基速追））,其中,施肥处理的总施氮量均为150 kg·hm^-2,另设一个不施氮肥的处理作为对照,记为N₀;以F优498为试验材料,以毯苗机插和缓释肥一次基施为参照,研究钵苗机插和氮肥缓速配施下的杂交籼稻氮素吸收利用特征。【结果】与毯苗机插相比,钵苗机插杂交籼稻拔节至抽穗阶段的氮素吸收速率显著加快了0.49—1.33 kg·hm^-2·d^-1,抽穗至成熟阶段的茎叶氮素转运量、转运率以及氮素转运对穗部的贡献率均显著提高,抽穗期和成熟期植株的氮素吸收量分别显著提高了12.63%和5.20%;干物质、稻谷生产效率和氮素收获指数分别提高了8.19—11.39、0.66—5.72和5.41—6.42个百分点;氮肥农学利用率、生理利用率和偏生产力平均分别提高了12.62%、11.94%和8.69%,有效穗数和每穗粒数也显著提高,2016年和2017年的平均产量分别提高了1 042.4 kg·hm^-2和722.3 kg·hm^-2（增产幅度分别达到10.30%和7.2%）。在钵苗机插下,与缓释肥一次性基施相比,缓速基施降低了抽穗期和成熟期的氮素积累量,加快了播种至拔节阶段的氮素吸收速率和积累量,但拔节至抽穗阶段显著降低,造成氮肥回收利用率和生理利用率明显降低,此外,它还降低了每穗粒数和单位面积颖花数,导致2年的平均产量下降了3.66%;而缓基速追在抽穗期和成熟期氮素积累量分别提高了2.34%和1.80%,拔节至抽穗阶段氮素吸收速率和吸收量分别提高了0.60 kg·hm^-2·d^-1和18.01 kg·hm^-2,氮肥回收利用率提高了2.84个百分点,农学利用率、生理利用率和偏生产力分别提高了12.54%、7.91%和52.55%,其每穗粒数和单位面积颖花数也得到了显著提高,最终产量显著提高了4.61%。【结论】 钵苗机插杂交籼稻在氮素利用效率方面比毯苗具有明显优势,而且采用“缓基速追”的施肥方式,能进一步提升钵苗机插杂交籼稻氮素的吸收与转运能力,进而提高了产量。

Effects of Combined Application of Slow Release Nitrogen Fertilizer and Urea on the Nitrogen Utilization Characteristics in Machine- Transplanted Hybrid Rice

【Objective】The aim of this study was to investigate using the big panicle advantage of indica hybrid rice to obtain a high-yield under the potted machine-transplanted and combined application of slow release nitrogen (N) fertilizer and urea, and to explore N utilization characteristics of the potted-seedling machine-transplanted hybrid indica rice in the Southwest rice region, so as to provide the theoretical and practical basis for the technology of saving-fertilizer and high-yield of machine-transplanted hybrid rice seedling in China. 【Method】 A 2-year split-plot experiment (2016-2017) was conducted in Meishan, Sichuan province, China. In the experiment, two machine-transplanted methods was set, including potted-seedling (M₁) and blanket-seedling (M₂), and four N treatments were set, including 150 kg·hm^-2 slow release N fertilizer (SRNF) as a base (N₁), 105 kg·hm^-2SRNF + 45 kg·hm^-2 urea as a base (N₂, SBUB), 105 kg·hm^-2 SRNF as a base + 45 kg·hm^-2 urea at the panicle initiation stage (N₃, SBUP), and another treatment without N fertilizer as a control (N₀). F-you 498 was the experimental variety, and the blanket-seedling machine-transplanted method and 100% slow-release N fertilizer as base were the reference. The N utilization characteristics of hybrid indica rice under the potted-seedling machine-transplanted and slow and rapid N fertilizer combined application were studied.【Result】Compared with the blanket-seedling rice, the potted-seedling significantly accelerated the N absorption rate by 0.49-1.33 kg·hm^-2·d^-1 from elongation stage to heading stage; The potted-seedling improved N transportation and N transportation efficiency of stems and leaves, and the contribution rate of N transportation from heading to maturity; The potted-seedling increased the N accumulation at heading and maturity by 12.63% and 5.20%, respectively; The potted-seedling increased N use efficiency for biomass production and grain yield, and N harvest index by 8.19-11.39, 0.66-5.72 and 5.41-6.42 percentage points, respectively; The potted-seedling improved N agronomic efficiency, N physiological efficiency, and partial factor productivity by 12.62%, 11.94% and 8.69%, respectively; The potted-seedling improved the effective panicles and spikelets per panicle, and improved the yield on 1 042.4 kg·hm^-2 and 722.3 kg·hm^-2, and increased by 10.3% and 7.2%, in 2016 and 2017, respectively. Under the potted-seedling, compared with 100% SRNF as base, SBUB decreased the N accumulation at heading stage and maturity stage, accelerated the N absorption rate and N accumulation from sowing stage to elongation stage, but decreased them from elongation to heading; N recovery efficiency, N physiological efficiency, the spikelets per panicle and spikelets per unit area under SBUB were significantly decreased, then the mean yield of 2 years decreased by 3.66%. Conversely, compared with 100% SRNF as base, SBUP increased the N accumulation at heading and maturity by 2.34% and 1.80%, respectively; SBUP improved the N absorption rate by 0.60 kg·hm^-2·d^-1 and N accumulation by 18.01 kg·hm^-2 from elongation to heading; N recovery efficiency under SBUP were improved by 2.84 percentage points, and N agronomic efficiency, N physiological efficiency, and partial factor productivity by 12.54%, 7.91% and 52.55%, respectively; SBUP improved the spikelets per panicle and spikelets per unit area, then the yield improved by 4.61%.【Conclusion】Compared with the blanket-seedling, the potted-seedling had obvious advantages on N utilization efficiency, and SBUP could further enhance its N absorption and transfer capacity, then improved indica hybrid rice yield.