研究种植密度对玉米群体特征及产量的影响，旨在探明实现春玉米进一步增产的调控途径，同时确定陕北灌区玉米适宜种植密度。于2018-2019年以陕科9号和大丰30为材料，设置4个密度4.5万株?hm-2、6.0万株?hm-2、7.5万株?hm-2和9.0万株?hm-2进行田间试验。分析了玉米冠层结构、光合性能以及产量构成指标。结果表明，2个品种籽粒产量随密度增大先增加后降低的趋势，均在密度7.5万株?hm-2时产量最高，2年平均产量分别为14.1和13.2 t?hm-2；随种植密度增大亩穗数显著增加，而穗粒数和百粒重减少。随着密度的增加，2个品种能够调节穗上中部叶倾角、株型变紧凑，穗位层接受到更多的光能，增加了群体光合速率，积累更多光合同化物，但高密度条件下陕科9号协调形态结构和生理功能方面优于大丰30。可见，适当增加密度配合耐密品种是陕北灌区春玉米增产的重要途径。玉米种植密度7.5万株?hm-2适合该区大面积推广。
英文摘要:
The aim of this study was to explore the canopy characteristics for high yield under increased plant density and determine the suitable planting densities in the irrigated region of north Shaanxi. Four plant density 45000, 60000, 75000 and 90000 plantshm-2were designed during 2018 and 2019 growing seasons. Two maize cultivars SK 9 and DF 30 were used to explore the effects of planting density on leaf area index, leaf direction value, light energy interception rate, photosynthetic characteristics and yield traits of maize. The results showed that the grain yield of the two cultivars increased then decreased with the increase of density, and the highest yield was obtained at the density of 75000 plantshm-2, the average yield of the two years was 14.1 t hm-2 and 13.2 t hm-2, respectively. The number of productive ear was remarkably increased with the increasing of planting density, but the seed numbers per ear and 100-kernel weight decreasedwith the increase of planting density. With the increase of planting density, the two cultivars can adjust the leaf angle of upper ear, plant type becomes compact, the leaf layer of ear position receives more light energy, improving the photosynthetic performance of population, and resulting in making more accumulation of photosynthetic production; but the coordination morphological structure and physiological function of SK 9 is better than DF 30 under the higherplant density, indicating that the grain yield potential of SK 9 is higher than DF 30. We conclude that properly increasedplant density couple with density tolerant cultivars is potential way to improve the maize yield in the irrigation area of Northern Shaanxi. The optimal planting density of maize is 75000 plantshm-2, which is suitable for the large-scale promotion in this area.
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