水氮耦合对滴灌玉米光合特性及产量的调控效应

Regulatory effects of water-nitrogen coupling on photosynthetic characteristics and yield of drip-irrigated maize

探索水氮施用对玉米光合参数及产出指标的影响规律,寻求适宜水氮耦合量,为西辽河流域水肥管理提供理论和应用参考。膜下滴灌田间试验设置三种灌溉水平与三种施氮量组合形成9个处理,对比分析不同水氮组合作用效果。结果表明,水氮两因素对玉米光合速率Pn、蒸腾速率Tr、气孔导度Gs、胞间二氧化碳浓度Ci影响程度表现为灌水>施氮,对叶片水分利用效率WUE影响程度表现为施氮>灌水。对于Pn,W_(2)N_(2)(中水中氮)显著高于W_(3)N_(1)(高水低氮)、对于Tr,W_(2)N_(2)和W_(3)N_(1)差异不显著,因此灌溉量由中水至高水(1802~2315 m^(3)·hm^(-2))对Pn提升作用无法补偿中氮240 kg·hm^(-2)降至低氮192 kg·hm^(-2)对Pn的削弱作用,但可补偿对Tr的负效应。中高灌溉水平下氮肥192~240 kg·hm^(-2)可有效提升Pn、Tr、百粒重、穗粒重(W_(2)N_(2)显著高于W_(2)N_(1)、W_(3)N_(2)显著高于W_(3)N_(1)),继续施氮无显著作用。玉米产量提升与Pn、Tr增大呈正相关,水分亏缺时中氮240 kg·hm^(-2)至高氮288 kg·hm^(-2)无明显增产作用,中等灌溉水平下氮肥增产效果显著。W_(3)N_(2)(高水中氮)耦合下玉米可获得最佳光合能力及产量水平,但超过W_(2)N_(2)(中水中氮)的耦合量对WUE无增效、降低光合产物在籽粒中的分配比例。综合考虑光合参数及产量,推荐中等至较高的灌溉水平1802~2315 m^(3)·hm^(-2)(W2~W3)与中等施氮水平240 kg·hm^(-2)(N2)为最优水氮耦合量。

The effects of water and nitrogen on the photosynthetic parameters and output indices of maize were studied,and the appropriate amount of water-nitrogen coupling was sought to provide theoretical and application references for water and fertilizer management in the West Liaohe River Basin.Comparative analysis of the effects of different water-nitrogen combinations in a field experiment with nine treatments formed by combining three irrigation levels and three nitrogen application amount drip irrigation under film.The effects extent comparison of water-nitrogen factors on photosynthesis rate Pn,transpiration rate Tr,stomatal conductance Gs,and intercellular carbon dioxide concentration Ci of maize was irrigation>nitrogen,and the effect on leaf water use efficiency WUE was nitrogen>irrigation.For Pn,W_(2)N_(2)(moderate water and moderate nitrogen)was significantly higher than that of W_(3)N_(1)(high water and low nitrogen),and for Tr,there was no significant difference between W_(2)N_(2) and W_(3)N_(1).Accordingly,the increase of water from middle to high irrigation volume of 1802-2315 m^(3)·hm^(-2) could not compensate for the decrease of nitrogen from 240 kg·hm^(-2) to 192 kg·hm^(-2),but could compensate for the negative effect on Tr.Under medium and high irrigation levels,nitrogen fertilizer from 192-240 kg·hm^(-2) could effectively increase Pn,Tr,hundred-grain weight,and grain weight per ear(W_(2)N_(2) was significantly higher than W_(2)N_(1),and W_(3)N_(2) was significantly higher than that of W_(3)N_(1)),while continued nitrogen application had no significant effect.The increase in maize yield was positively correlated with the increase of Pn and Tr.When water deficit occured,there was no significant increase in yield from moderate nitrogen of 240 kg·hm^(-2) to high nitrogen of 288 kg·hm^(-2),while nitrogen fertilizer had a significant increase in yield under moderate irrigation levels.Under W_(3)N_(2)(high water middle nitrogen coupling),maize could obtain the best photosynthetic capacity and yield level,but exceeding the coupling amount of nitrogen in the middle water had no effect on WUE and reduced the distribution proportion of photosynthetic products in grains.Considering photosynthetic parameters and output 1802-2315 m^(3)·hm^(-2) and the moderate nitrogen application level 240 kg·hm^(-2) were the optimal water-nitrogen coupling amount.