不同水氮管理模式下玉米光合特征和水氮利用效率试验研究

Photosynthesis, Water and Nitrogen Use Efficiency of Maize as Impacted by Different Combinations of Water and Nitrogen Applications

【目的】提高水氮利用效率、玉米产量和经济效益。【方法】设置3个灌水定额水平(W0:0 mm、W1:40 mm、W2:80 mm),4个施氮量水平(N0:0 kg/hm2、N1:180 kg/hm2、N2:230 kg/hm2、N3:280 kg/hm2),分析比较了不同水氮管理模式对拔节期春玉米光合速率、叶片瞬时水分利用效率(WUEi)、成熟期地上部分干物质量、产量、水分利用效率(WUE)、氮素积累量以及对氮素利用的影响。【结果】施氮可以显著提高拔节期光合速率,当施氮量由230 kg/hm2提高到280 kg/hm2,光合速率的增幅减小。施氮对WUEi有促进作用,而灌水定额在40～80 mm之间时,增加灌水定额不利于WUEi提高。N2W1处理的成熟期地上部分干物质累积量和产量较N0W0处理分别提高54.27%和78.36%。玉米水分利用效率在2.31～3.61 kg/m3之间,在各施氮水平下WUE表现为W0水平>W1水平>W2水平。灌水施氮处理植株和籽粒的氮素累积量明显高于N0W0处理的,施氮对成熟期籽粒和植株的氮素累积均有显著影响(P<0.05)。W1水平下植株氮素积累量与W0水平差异显著,但与W2水平差异不大。W1水平下的籽粒氮素积累量最大,与W0水平差异显著。氮肥偏生产力随施氮量的升高而减小,在同一个施氮水平下,氮肥偏生产力表现为W1水平>W2水平>W0水平。N2W1处理的氮素籽粒生产效率最高,除N3处理外,当灌水定额增加时,氮素籽粒生产效率有所增加,但增幅变小。【结论】增加施氮量可以提高产量和干物质量积累,提升水分利用效率,而氮素利用效率随着施氮量的增加呈先增加后减小的趋势,氮肥偏生产力与施氮量负相关。建议当地采取灌水定额40 mm,施氮量230 kg/hm2的灌水施氮方式。

【Objective】This paper aimed to find an optimal combination of water and nitrogen application which can simultaneously improve their use efficiency by maize under sprinkler irrigation.【Method】The experiment consisted of three irrigation levels : No irrigation(W0); irrigating 40 mm(W1) and irrigating 80 mm(W2); and four nitrogen fertilizer applications: No fertilizer(N0), 180 kg/hm^2(N1), 230 kg/hm^2(N2) and 280 kg/hm^2(N3).In each treatment, we measured photosynthetic rate, leaf water use efficiency(WUEi) at jointing stage, above-and below-ground biomass at mature stage, yield, overall water use efficiency(WUE) and nitrogen accumulation and nitrogen fertilizer utilization.【Result】With increase in nitrogen fertilizer application, the photosynthetic rate at the jointing stage increased but at a decreasing rate. Nitrogen fertilizer application had a positive effect on WUEi,but was less effective when the irrigation amount was between 40 mm and 80 mm. Compared with N0+W0, N2+W1 increased the above-ground biomass and yield by 54.27% and 78.36% respectively. The WUE varied between2.31 to 3.61 kg/m3, and under the same nitrogen application, the WUE of different irrigations ranked in W0>W1>W2. Irrigation and nitrogen application increased nitrogen accumulation in plants and grains, especially nitrogen application whose impact at the maturity stage was significant(P<0.05). Nitrogen accumulation peaked in W1 differing significantly from that in W0, but was statistically the same as that in W2. The partial productivity of nitrogen decreased with the increase in nitrogen fertilizer application. Under the same nitrogen fertilizer application,the partial production of irrigation was ranked in W1>W2>W0. N2+W1 gave the highest NUW in terms of grain output. Except N3, the grain production efficiency of nitrogen increased with irrigation amount despite at a decreasing rate.【Conclusion】With nitrogen application increasing, both dry biomass and WUE increase but the NUW increases at a decreasing rate. Partial productivity of nitrogen is negatively related to nitrogen application.The experimental results suggest that irrigating 40 mm and applying 230 kg/hm^2 of nitrogen is an optimal combination under sprinkler irrigation.