种植密度和行距配置对玉米群体光分布与群体光合特性的影响

随密度增加,群体内光合有效辐射(PAR)总截获率相应增大,上层截获率增大,穗位叶层和下层截获率下降。三个密度条件下,总截获率、穗位叶层及下层截获率均以"80+40"配置为最高;上部截获率以"60+60"配置最高,且随着大行距的增大呈递减趋势。花后群体光合速率(CAP)随密度增加相应升高;同一密度下,各行距配置间表现为"80+40">"70+50">"60+60">"90+30",且随密度增大差异变大。群体呼吸效率(CR)花后呈现先降低、后升高的趋势;不同生育期均表现为随密度增加而增大的趋势。群体呼吸速率占群体总光合的比例(CR/TCAP)随密度增大而增大;相同密度下,"80+40"配置显著低于其他配置,且随密度增大表现更加突出。

Effects of Planting Density and Row Spacing Form on Canopy Light Distribution and Photosynthesis Characteristics of Maize

With the increase of planting density,the total capture ratio and the capture ratio in upper layer of the photosynthetically active radiation(PAR) raised,while the capture ratio in ear-leaf and lower layers decreased.Under the three densities,the total capture ratio and capture ratio in ear-leaf and lower layers of the "80+40" form was the largest;the capture ratio in upper layer was the highest under the form of "60+60",and it decreased with the increase of the wide row spacing.The canopy apparent photosynthesis(CAP) rate after anthesis increased corresponding to the increase of density.At the same density,the sequence of CAP rate among all forms was "80+40">"70+50">"60+60">"90+30" and the difference became larger with the density raising.The canopy respiration(CR) after anthesis decreased first and increased later.At each growth stage,the CR value and ratio of CR/TCAP increased with the density increase.Under the same density,the ratio of CR/TCAP of "80+40" form was obvious lower than that of the other ones and the trend performed very conspicuous under higher densities.