覆膜和种植密度对旱作春玉米产量和蒸散量的影响

为探究黄土高原旱作玉米的适宜种植密度,开展了玉米露地与覆膜6个种植密度的大田试验。结果表明:覆膜加速了玉米的生长和发育,表现在株高和叶面积指数的增加,生育期的提前,如抽穗期(即最大高度出现时)比露地种植提前了11 d。在玉米生长的中后期,露地玉米株高具有随密度增加而降低的趋势,而覆膜玉米则无显著差异。无论是覆膜还是露地种植,玉米叶面积指数都是随种植密度的增加而提高。玉米的蒸散量随种植密度的增加而增加,但覆膜种植降低了玉米对水分的消耗,在不同程度上缓解了因种植密度增加而导致的蒸散量增加与降水不足之间的矛盾。覆膜显著提高了玉米产量和水分利用效率,平均产量和水分利用效率较露地种植分别提高52.79%和60.55%。露地与覆膜种植产量和水分利用效率随种植密度的增加都呈现先增加后减小的趋势,但获得最高产量与水分利用效率对应的种植密度不同:露地种植在密度为52 500株/hm~2(D2)时获得最高产量和水分利用效率,而覆膜种植增大了单位面积土地可支撑的群体,最高产量和水分利用效率分别在密度为82 500株/hm~2(D4)和67 500株/hm~2(D3)时获得,但D3与D4下水分利用效率无显著差异,所以在试验气候年型下,黄土高原东部露地和覆膜种植的春玉米适宜密度分别为52 500株/hm~2和82 500株/hm~2。

Effects of Plastic Film Mulching and Plant Density on Yield and Evapotranspiration of Rainfed Spring Maize

Concerning the increasing of plant density is one of important ways to achieve high yield, field experiments were conducted to investigate the effects of increasing plant density and plastic film mulching on the growth and yield of spring maize, and crop evapotranspiration. The results showed that film mulching accelerated growth and development of maize. It also increased height and leaf area index of the plant at early growth stage of maize. At the late growth stage of maize, plant height of maize without film mulching was decreased with the increase of density, but no significant difference was found for plastic film mulching. Whether mulching or un-mulching, leaf area index of maize was increased with the increase of the density. Evapotranspiration increased with the increase of the density, however, film mulching reduced consumption of water and alleviated the contradiction between increase of water consumption because of the increased plant density and plant height and insufficient precipitation. Film mulching significantly increased maize yield and water use efficiency by 52.79% and 60.55% compared with un-mulching. The grain yield and the water use efficiency of un-mulching and film mulching treatments were all increased with the increase of the plant density until a plateau and then declined. The difference was that the maximum yield of un-mulching was 8466.02kg/hm2 and it was achieved at 52500 plants/hm2, however, the maximum yield of film mulching was 12778.47kg/hm2 and it was achieved at 82500 plants/hm2. As a result, the optimum planting densities on eastern Loess Plateau for film mulching and un-mulching of spring maize were 52500 plants/hm2 and 82500 plants/hm2.