Regulatory effects of water-nitrogen coupling on photosynthetic characteri-stics and yield of drip-irrigated maize
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,W2N2(moderate water and moderate nitrogen)was significantly higher than that of W3N1(high water and low nitrogen),and for Tr,there was no significant difference between W2N2 and W3N1.Accordingly,the increase of water from middle to high irrigation volume of 1 802-2 315 m3·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(W2N2 was significantly higher than W2N1,and W3N2 was significantly higher than that of W3N1),while continued nitrogen application had no significant effect.The increase in maize yield was posi-tively 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 W3N2(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 1 802-2 315 m3·hm-2 and the moderate nitrogen application level 240 kg·hm-2 were the optimal water-nitrogen coupling amount.
water-nitrogen couplingphotosynthetic parametersdrip irrigation under filmintegra-tion of water and fertilizermaize
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