耐密性玉米冠层结构对密度的响应

以华美1号和郑单958为材料,以1.5万株为梯度,共设置12个密度处理,种植密度自1.5万株/hm~2增至18万株/hm~2,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/hm~2时产量达到最高,为15 912.8 kg/hm~2;郑单958在6.0万株/hm~2时产量最高,为13 685.9 kg/hm~2。在适当高的种植密度内(华美1号为9.0万~13.5万株/hm~2,郑单958为6.0万~9.0万株/hm~2),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。

Canopy Structure of Density-Resistant Maize Cultivars under Different Plant Densities

Two commercial available cultivars of Huamei 1(HM1) and Zhengdan958(ZD958), were planted under 12 different densities from 15 000 plants/ha to 180 000 plants/ha with a gradient of 15 000 plants/ha. Canopy structure and characteristics of high-yield and high-efficiency spring maize were studied. The highest yield of HM1 and ZD958 were 15 912.8 kg/ha at density of 120 000 plants/ha and 13 685.9 kg/ha at plant density of 60 000 plants/ha, respectively. For HM1, LAI was approximately 4.19-5.30 at silking stage. Moreover, the transmission percentage of ear layer was around 17.57%-23.79%. For ZD958, LAI is approximately 4.71-6.54 at silking stage, and the transmission percentage of ear layer was 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 18 000-60 000 plants/ha, 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.