施氮对杂交谷子产量与光合特性及水分利用效率的影响

Effects of nitrogen application on yield,photosynthetic characteristics and water use efficiency of hybrid millet

【目的】随着杂交谷子高产特性的凸显和栽培技术研究的不断深入,确立高产条件下的合理施肥方案具有重要现实意义。本文设定了不同氮素水平,研究施氮量对谷子生物量、产量、光合特性及水分利用效率(WUE)的影响,以确定杂交谷子高产的合理施氮方案。【方法】以"张杂5号"谷子为对象,采用田间小区试验,设施氮量0、100、200、300(分3次施)、300(分2次施)、400 kg/hm2共6个氮素水平(N0~N5处理),通过测定杂交谷子籽粒产量、生物量、农田耗水量和光合特性,分析施氮与杂交谷子产量、光合特性及水分利用效率(WUE)之间的关系。【结果】谷子产量、光合特性及WUE与施氮水平密切相关。不同施氮处理谷子生物量比对照N0处理增加了26.33%~87.21%,处理间差异显著。谷子籽粒产量以N3(300 kg/hm2,分3次施)和N5(400 kg/hm2)处理较高,分别为8202 kg/hm2和8537 kg/hm2,两处理间差异不显著。各生育阶段谷子的耗水特征变化趋势不同。生育前期耗水变化不明显,拔节-抽穗期谷子农田耗水量以N0处理日均耗水量最大;在生育后期N0处理耗水量最小,N3耗水量最大。全生育期谷子总耗水量处理间差异较小,以N1(100 kg/hm2)处理总耗水量最大。杂交谷子叶片的净光合速率、蒸腾速率和气孔导度均以N0处理最小,N3处理为最大。籽粒水分利用效率、生物水分利用效率及单叶水分利用效率均以N3处理为最高。本试验条件下,施氮量为400 kg/hm2时,虽获得了最高产量,但与施用N 300kg/hm2差异不显著,且水分利用效率较低,说明高量施氮的增产效果不明显。【结论】氮素的合理使用协调了水氮关系,提高了水分利用效率。同时,施氮还提高了杂交谷子的净光合速率、蒸腾速率和气孔导度。施氮量相同,但施肥时期不同,产量和WUE也差异显著。谷子生育前期大量施肥降低了营养物质向籽粒的转移,产量较低。因此,推荐施氮300 kg/hm2(分3次施)作为本地区杂交谷子高产高效的合理施氮量。

Objectives] The rational fertilization schedule has being required by the steadly increasing of yield of hybrid millet and intensive cultivation technique.A field experiment was conducted to study the influence of nitrogen application rate on biomass, yield, photosynthetic characteristics and water use efficiency ( WUE ) of hybrid millet for determining the rational nitrogen application scheme.[Methods]The field experiment was conducted with‘Zhangzagu No.5’ hybrid millet as research object.The study consisted of 6 nitrogen application rates, 0, 100, 200, 300 kg/ha (application for three times), 300 kg/ha (application for two times) and 400 kg/ha with the treatments code from N0 to N5 continuously.[Results]The yield, photosynthetic characteristics and water use efficiency of millet are significantly related to nitrogen application levels.The hybrid millet biomass in the nitrogen application treatments are increased by 26.33%-87.21%than that in the control treatment (N0), and the variation of biomass in different treatments was significant.The higher millet grain yields are in the N3 (300 kg/ha) and N5 (400 kg/ha) treatments, which are 8202 kg/ha and 8537 kg/ha respectively, and the difference between N3 and N5 is not significant.The variation tendency of water consumption is different at the growing stages of millet.At the early growing stages the water consumption of hybrid millet is not changed significantly, and the maximum daily water consumptions are in the N0 treatment at the jointing and heading stages.The largest daily water consumption is in the N3 treatment at the late growth stage.The variation of total water consumption in whole growing period of millet is relatively small,the largest total water consumption is in the N1 treatment.The smallest net photosynthetic rates ( Pn) , transpiration rates ( E) and stomatal conductances ( C) of hybrid millet are separately in the N0 and and the largest in N3 treatments.The highest water use efficiencies of yield (WUE), of dry matter (WUEDM) and of single-leaf (WUESL) are all in the N3 treatment.Under the highest nitrogen application amount, 400 kg/ha ( N5 ) , the highest yield of millet is obtained, while the water use efficiency is lower than that in the N3 treatment.[Conclusions] The rational use of nitrogen increases Pn, E and C of hybrid millet and coordinates the relationships between the water and nitrogen, improves the water use efficiency.The same amount of nitrogen application the yields and WUEs are significantly different when the fertilization are applied different periods.The larger amount of nitrogen application at the earlier growing period of millet decreases the nutrients translocation to grains, and has low yield.N 300 kg/ha ( application for three times) is proposed as the rational amount of nitrogen application for higher yield of hybrid millet in the region.