种植密度对夏玉米果穗叶生理功能衰退的影响

以郑单958为供试品种，在大田条件下研究不同种植密度对夏玉米果穗叶生理功能衰退特性的影响。结果表明：果穗叶叶绿素a+b含量、原初光化学效率(F_v/F_m)、光系统Ⅱ(PSⅡ)潜在活性(F_v/F_o)、可溶性蛋白、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性均随果穗叶功能期的推进呈下降趋势，且随密度的增大下降趋势明显，吐丝后39d下降最显著；果穗叶叶绿素a/b、丙二醛(MDA)含量呈逐渐上升趋势。随着种植密度的增大，果穗叶光能转化和自身保护酶系活性下降，光合生产能力减弱，造成果穗叶生理功能早衰，缩短了叶片功能期。

Effects of Planting Density on Physiological Decline on Ear Leaf of Summer Maize

Taking Zhengdan958 as material, six density levels were designed to investigate the effects of different planting density on physiological decline on ear leaf of summer maize.The results showed that with ear leaf functional stage developing, Chl(a+b), maximum photo-chemical efficeiency(F_v/F_m), PS Ⅱ potential activity(F_v/F_o), light-saturated photosynthetic rate(Pnmax), apparent quantum yield(AQY), soluble protein content, SOD activity,CAT activity all took on decline tendency, and they were decreased with density increasing, especially after silking 39 days.Chl(a/b), MDA content showed a gradually increase tendency.The increasing of cultivation density leaded to the decline of ear leaf physiological function and self-guard enzyme activity and eventually shortening leaf functional stage, decreasing its photosynthesis.