Objective The response of maize root characteristics on population density were studied .[Method] Four maize varieties Yifeng29, Zhengdan958, Xianyu335 and Xianyu420 were used as the tested materials.The number of brace root , dry mass and protective enzyme activities of root were meas-ured, and the effects of population density on basic characteristics of root were determined .[Result and conclusion] With the increase of population density , the number of brace root , dry mass and root activity increased first and then decreased , and the peaks occurred under different treatments .Protective enzyme activities of root were different with varieties , and MDA contents increased with the increase of population density .The percentage of lodging , the number of brace root and dry mass of root of Zhengdan 958 were the biggest , while Xianyu335 had a higher protective activities .%【目的】从玉米根系形态及生理学角度探讨根系对群体密度变化的响应机制。【方法】以益丰29、郑单958、先玉335和先玉420共4个玉米品种为试验材料，通过气生根数目、根系干质量及保护酶活性等指标，分析群体密度对玉米根系基本特征的影响。【结果和结论】过高的群体密度对根系的形态及生理特性存在一定的负效应。随着密度的增加，气生根数量、根系干质量、根系活力均先升高后降低，最大值因品种和生育时期而不同；根系保护酶活性的变化规律则因品种各不相同，但以先玉335最高；随种植密度增加，MDA含量逐渐增加。在气生根数量和根系干质量方面，郑单958表现最好。
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