Effects of Planting Density under Different Row-Spacings on Photosynthesis and Yield of Maize

A semi-compact maize cultivar,which is best adaptable to the environment of Chongqing and Southwest China,was grown in a field experiment of two-factor split-plot design with four planting densities(main plots) and three row-spacings(sub-plots) to study the influence of planting density and row-spacing on yield and agronomic characters of maize so as to provide a theoretical and practical basis for maize cultivation in Chongqing and Southwest China.The result showed that maize yield was highly significantly influenced by planting sensity,being the highest when the planting density was 3 500 plants/mu(667 m2).Planting density had highly significant effects on ear length,ear width and kernels per row,a significant effect on 100-kernel weight and no significant effect on rows per ear and bald length.With increasing planting density,plant height and ear height increased,stem diameter declined,photosynthetic rate dropped and the leaf area of the ear leaf first increased and then decreased.Maize yield was significantly influenced by row spacing,being the highest with a spacing of 0.9 m.Row spacing had no significant effect on ear characters.With increasing row spacing,plant height,ear height,photosynthetic rate and ear leaf first increased and then decreased and stem diameter showed a downward trend.Interaction between planting density and row spacing had no significant effect on yield.In conclusion,planting density and row spacing had a regulation effect on yield,yield-related traits and agronomic characters,and the combination of 3500 plants/ha and a row spacing of 0.9 m is recommended for maize cultivation in Chongqing.