种植密度和行距配置对超高产夏玉米群体光合特性的影响

在67 500株 hm^-2、90 000株hm^-2和112 500株hm^-2等3个种植密度条件下，研究了密度和行距配置对超高产夏玉米品种登海701产量和群体光合特性的影响。结果表明，随密度增加，籽粒产量、叶面积指数(LAI)、光合有效辐射(PAR)上层截获率、群体光合(CAP)和群体呼吸(CR)、干物质积累量均提高；而叶绿素含量、穗位叶层和下层PAR截获率则降低。在67 500株 hm^-2下，宽窄行与等行距处理相比无显著优势。但在90 000株 hm^-2和112 500株 hm^-2密度下，80 cm+40 cm行距处理的产量、叶面积指数(LAI)、叶绿素含量、穗位叶层的PAR截获率、花后群体光合速率(CAP)平均值均显著高于其他行距处理(等行距、70 cm+50 cm和90 cm+30 cm)；而群体呼吸速率与光合速率的比值(CR/TCAP)则显著低于其他行距处理。说明在较高密度条件下，80 cm+40 cm的宽窄行配置有助于扩大光合面积、增加穗位叶层的光合有效辐射、提高群体光合速率、减少群体呼吸消耗，从而提高籽粒产量。

Effects of Planting Density and Row Spacing on Canopy Apparent Photosynthesis of High-Yield Summer Corn

With different plant population densities (6.75´10⁴, 9.00´10⁴, and 11.25´10⁴ plants ha^-1), the effects of the deneity and row spacing on grain yield and canopy apparent photosynthesis were studied in this article. The results were as follows: with the increase of planting density, grain yield, leaf area index (LAI) and capture efficiency of photosynthestically active radiation(PAR) in upper leaf layer, as well as canopy apparent photosynthesis (CAP) and canopy respiration (CR) and dry matter quantity increased accordantly; but, chlorophyll content and capture efficiency of PAR in the middle and lower layers of canopy decreased. Within different row spacing treatments, the wide-narrow row spacing were not superior to the uniform one significantly at 6.75´10⁴ plants ha^-1. However, at 9.00´10⁴ and 11.25´10⁴ plants ha^-1, grain yield, LAI, chlorophyll content, capture efficiency of PAR in middle leaf layer and average rate of CAP after anthesis in row spacing of “80 cm+40 cm” were remarkably higher than those in other three row spacings (uniform, 70 cm + 50 cm, 90 cm + 30 cm); while CR/TCAP (ratio of canopy respiration to total canopy apparent photosynthesis) in row spacing of ’80 cm+40 cm’ was the lowest, compared to the others. From the above, it was suggested that at higher plant density the row spacing of ’80 cm+40 cm’ could enlarge photosynthetic area, enhance PAR in middle leaf layer, increase CAP, reduce CR and improve grain yield.