Effects of Abiotic Stress on Yield Traits of Maize Hybrids and Their Parental Inbred Lines

The field experiments were conducted to study the changes of grain yield and concerned physiological traits in stress-tolerant maize variety Zhengdan 958 and its parental inbred lines(Zheng 58 and Chang 7-2),as well as stress-sensitive maize variety Shaandan 902 and its parental inbred lines(K22 and K12) under different treatments of density(45 000 and 75 000 plants ha?1),nitrogen application(112.5 and 337.5 kg ha?1),and irrigation(normal irrigation and controlling water at prophase).The results showed that there were little differences in yield,mean leaf area index after anthesis,mean SPAD after anthesis,post-anthesis dry matter accumulation and harvest index between Zhengdan 958 and Shaandan 902 under resource-replete condi-tions(low density,high nitrogen and normal irrigation).But there were great differences in all traits(besides harvest index) be-tween Zhengdan 958 and Shaandan 902 under abiotic stress(high density,low nitrogen and drought stress),with much higher values in Zhengdan 958 than in Shaandan 902.Compared with Shaandan 902,mid-parent values of leaf area index,SPAD,post-anthesis dry matter accumulation and grain yield of Zhengdan 958 under abiotic stress(high density,low nitrogen and drought stress) increased by 45%,36%,51%,and 45%,respectively,and heterosis of Zhengdan 958 increased by 18%,9%,28%,and 22%,respectively.The mid-parent value of yield was much higher than heterosis of yield and both of them were higher in Zhengdan 958 than in Shaandan 902.So the maize variety Zhengdan 958 showed greater tolerance to abiotic stress which was mainly inherited from its parental inbred lines.Higher SPAD and LAI after anthesis contributed to post-anthesis dry matter accu-mulation,resulting in higher yield and higher stress tolerance.