PurposeTo study the mechanism of nitrogen fertilizer affecting maize yield and water use efficiency, proposing a suitable nitrogen application rate for dryland maize.
MethodFour nitrogen fertilizer levels (N0: 0 kg/hm2, N1: 100 kg/hm2, N2: 200 kg/hm2 N3: 300 kg/hm2) were set to study the effects of different nitrogen rates on soil water deficit, leaf protective enzyme activities, photosynthetic performance, grain yield and water use efficiency.
ResultsIncreasing nitrogen application rate increased dry matter accumulation, grain yield, and water use efficiency, but there was no significant difference between N2 and N3 treatments (P>0.05). The grain yield and water use efficiency of N2 was 10 542.67 kg/hm2 and 22.28 kg/(mm·hm2), respectively, and were increased by 161% and 132% as compared to N0. The highest grain yield and nitrogen fertilizer application fitted by this equation were close to the N3 treatment. Nitrogen application rate had a significant impact on corn water consumption (P<0.05). During the growth stage, the soil water deficit of nitrogen treatment was greater than N0. Nitrogen application promoted corn growth, increased soil water consumption, and exacerbated soil water deficit. With the increase of nitrogen application rate, the SOD, POD and CAT activities of corn leaves increased, and the MDA and soluble sugar content increased, delaying leaf senescence and enhancing the drought resistance of corn. Furthermore, corn leaf PEP carboxylase, RuBP carboxylase activity and chlorophyll content and the net photosynthetic rate significantly increased (P<0.05) with the increase of nitrogen application rate.
ConclusionIn contrast to the N0 treatment, the nitrogen application rate at 200 kg/hm2 could increase drought resistance of corn, increase the photosynthetic carbon assimilation ability of corn, delay senescence, and improve the quality of corn dry matter, grain yield and water use efficiency.
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