关键词: 覆膜时期, 施氮量, 生理指标, 产量, 水氮利用效率

Abstract: 【Objective】To optimize the agricultural practice in supporting high production and high efficiency of spring maize cultivation in dryland region of eastern Gansu province, the effects of film mulching period and nitrogen addition level on maize physiology, yield, and water and nitrogen (N) use efficiencies were investigated in this study, using a compact maize variety (xianyu 335) with high stress resistance as tested crop.【Methods】A two-factorial experiment with split-plot design was established from 2012 to 2019, which consisted of two treatments of mulching period (spring and autumn mulching) and seven levels of N addition (0, 75, 150, 225, 300, 375, 450 kg N·hm^-2), and the physiological characteristics, yield variables, and water and N use efficiencies of maize plants under different treatments were annually measured.【Results】Film mulching and moderate levels of N addition increased the photosynthetic rate and the relative content of leaf chlorophyll (SPAD value), extended the green duration of leaves, efficiently balanced the source-sink relationship, and improved the grain number per spike and 100-grain weight. The yield, grain number per spike and 100-grain weight of maize were significantly affected by N application rate, annual rainfall pattern and their interactions, and all these variables showed similar trends of inverted U-shaped curves with the increasing of N addition levels. Maize yields under treatments with N addition of 150~450 kg N·hm^-2 were significantly higher than that of 75 kg N·hm^-2, with a peak (15142.5kg·hm^-2) occurring in the treatment with N addition of 300 kg N·hm^-2. The yields did not differ significantly between treatments with N addition of 225 kg and 300 kg N·hm^-2, whereas maize yield would not increase or even decline when N inputs were beyond the level of 300 kg N·hm^-2. Maize yield was highly dependent on the annual rainfall pattern and the amounts of precipitation in key growth periods, of which the rainfall amount from July to September, especially in early July (tasseling-silking stage of maize), as well as the type of drought year were especially important in determining maize yield. Furthermore, film mulching period, experimental year, nitrogen application rate and the interaction between nitrogen application rate and rainfall annual pattern also significantly affected the water use efficiency (WUE). The WUE under autumn film mulching was 8.6% higher than that under spring film mulching. The N partial factor productivity and N use efficiency under treatment of 225 kg N·hm^-2 were increased by 28.6% and 20.1% than that under 300 kg N·hm^-2, respectively. Moreover, the average N use efficiency was increased from 34.8% under treatment of 300 kg N·hm^-2 to 35.8% under 225 kg N·hm^-2. In other words, 225 kg N·hm^-2 can realize the simultaneous increases in maize yield and N use efficiency.【Conclusion】These results suggest that film mulching and nitrogen addition of 150~225kg·hm^-2 could be used as efficient models for maize cultivation, especially with autumn film mulching in dry years. Farmers should choose the appropriate mulching practice and N addition levels according to the weather forecast in annual rainfall types.

Key words: mulching period, nitrogen amount, physiological indices, yield, water and nitrogen use efficiency