研究玉米群体冠层结构对超高密度的响应，校正及补充北方春玉米区不同春玉米品种高产高效冠层结构的评价指标体系，为耐密性品种在实际生产中的适宜种植密度提供参考依据。以华美1号和郑单958为材料，以1.5万株为梯度，种植密度自1.5万株/hm2增至18万株/hm2，共设置12个密度处理，研究探讨高产高效春玉米的冠层结构特征和光合特性。结果表明，华美1号在12.0万株/hm2时产量达到最高，为15912.8 kg/ hm2；郑单958在6.0万株/hm2时产量最高，为13685.9 kg/hm2。在适当高的种植密度内 (华美1号为9.0万株/hm2~13.5万株/hm2，郑单958为6.0万株/hm2~9.0万株/hm2)，华美1号吐丝期最大LAI达4.19~5.30，群体穗位层透光率达17.57%~23.79%；郑单958吐丝期最大LAI达4.71~6.54，群体穗位层透光率达17.77%~23.66%。冠层内透光率、叶夹角、茎粗、叶片厚度、净光合速率和叶绿素相对含量均随密度增加而不同程度下降。华美1号穗位层及穗位层以上LAI占全株叶面积比例高，叶片小而厚，穗位层透光率好，各项冠层指标不同程度优于郑单958。本试验中超耐密型品种玉米种植密度较目前大田试验增加1.8~6.0万株/hm2，为超耐密型品种的适宜种植密度提供了参考依据。
英文摘要:
Plant density strongly affected canopy structure of maize, thus determined the yield production. However, current plant density remained at around 60 k plants /hm2, which in some extent limited the yield improvement. The suitable plant density for high productivity and high efficiency maize production system is urgently needed. Therefore, high plant density resistance maize cultivars were investigated under a broad range of plant densities in order to enrich the quantitative criteria for high-yield and high-efficiency canopy structure and provide a theoretical basis of optimum plant density for density-resistant maize cultivars. Field experiment was carried out in Shanxi province in 2014. Two commercial available cultivars, Huamei 1 (HM) and Zhengdan 958 (ZD), were planted under 12 different densities from 15 k plants/hm2 to 180 k plants/hm2 with a gradient of 15 k plants/hm2. Canopy structure and characteristics of high-yield and high-efficiency spring maize were studied. The highest yield of HM and ZD were 15912.8 kg/ hm2 at density of 120 k plants /hm2 and 13685.9 kg/hm2 at plant density of 60 k plants/hm2, respectively. For HM, LAI is approximately 4.19~5.30 at silking stage. Moreover, the transmission percentage of ear layer is around 17.57%~23.79%; For ZD, LAI is approximately 4.71~6.54 at silking stage, and the transmission percentage of ear layer is around 17.77%~23.66%. Furthermore, percent transmission of base and ear layer, leaf angle, stem diameter, leaf thickness, Pn and the SPAD value all decreased with the increase of planting density for both cultivars. Compared with previous research, the plant density of density-resistant maize cultivar in this research increased 18 ~ 60 k plants /hm2, which benefit the optimization of plant density for density-resistant maize cultivars. Combination of density-resistant maize cultivars and optimum plant density can establish high-yielding and high-efficiency canopy structure.
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