Study on different groups receive light posture and photosynthesis character of summer maize

Chinese. 试验对两个不同基因型品种在45000、60000、75000、90000和105000株／hm. 5个密度下，对叶面积系数和受光态势及光合特性的变化及与产量的关系进行了研究。结果表明：随着叶面积系数的增加，净同化率减少，作物生长率增加，但超过适宜叶面积系数后，作物生长率随叶面积系数的增大而减少。叶面积系数与产量的关系呈二次曲线变化，大喇叭口期、吐丝期、成熟期地面透光率与子粒产量的关系可用y=ax. ＋bx＋c来表示。随着密度的增加，单叶的光合速率、气孔导度和蒸腾速率下降，胞间CO2浓度升高，超过合理范围后，各指标变化幅度增加。群体光合势最高阶段主要在大口期至吐丝25d和吐丝25d至成熟期，在吐丝25d以前，随密度的增加群体光合势增强；在吐丝25d后，群体光合势在适宜范围内随密度的增加而提高，密度过大时光合势下降。合理密度下，群体整个生育期的叶面积系数变化平稳，成熟期的叶面积系数较高，生育后期光能截获量大，群体内透光率适宜。[著者文摘]

English. Studied of relationship of leaf area index and received light posture and photosynthesis character on different 2 genotype breeds and five densities （45 000, 60 000, 75 000, 90 000 and 105 000 plants/ha）, it was found that with the leaf area index increasing, assimilation rate was falling off, crop growth rate was increasing. When exceed the proper leaf area index, growth rate was falling by area index enhancing, the leaf area index and the output relation assume repeated curve change. Floor transmitting rate and seed granule output indicated that coming y=ax2＋bx＋c, in big bugle period and spinning period and maturity. By density was increasing, the simple leaf brightness was down, the air hole leading degree was rising, compatriot room CO2 thickness rose, every index changed extent within rational density group range, not too. The period of group light posture sum maximal stage was big bugle to after spin 25 days and after spinning 25 days to harvest. The group light posture was increasing with the density increasing before spin 25 days. After spin 25 days, Photosynthetic potential in the appropriate groups within the framework of the increase in the density increase, the density too much time of potential. Reasonable density, the leaf area index of groups throughout the growing period changed in a smooth. Maturity of the leaf area index higher, fertility late intercepted a large quantity of solar energy, suitable for groups within the transmission rate.