Comparison of Heat Tolerance of Maize Hybrids and Their Parental Inbreds with Different Genotypes
[Objective]In recent years,the adverse weather of high temperature and heat damage in the Huang-Huai-Hai maize region of China occurred frequently,which has become an important adverse factor threatening maize production.Study and clarify the effects of high temperature stress on male and female ear characteristics and yield of maize can provide useful guidance for the cultivation and selection of high temperature tolerant maize varieties.[Method]The variety of Zhengdan958(Zheng58×Chang7-2),Xianyu335(PH6WC×PH4CV),Jingnongke728(JingMC01×Jing2416),MC812(JingB547×Jing2416),and their parents were used as the test materials.High temperature stress before and after flowering(from V12 stage to 7 d after silking)were conducted.The effects of high temperature stress on the growth and development of male and female panicles,ASI,pollen activity,yield and yield components of different genotypes of maize hybrids and their parents were studied.[Result]High temperature stress before and after anthesis significantly reduced the ear length,rows per ear and grains per row of the tested maize varieties and their parents,and then resulted significant decrease in yield.Compared with the control,the grain number per spike of Zhengdan958,Xianyu335,Jingnongke728 and MC812 decreased by 22.28%,47.69%,6.13%and 8.11%respectively under high temperature stress,resulting yield decrease of 9.50%,50.61%,3.17%and 5.00%respectively.Among the parental materials,the decrease of rows per panicle,grains per row and yield of Jing2416 under high temperature treatment was the smallest and not significant,while the decrease of PH6WC was the largest.Under high temperature stress,the total number of tassel branches,the length of tassel,the total amount of loose pollen and pollen activity decreased significantly,the silking period of loose pollen was prolonged,and the duration of loose pollen was shortened.Among them,Jingnongke728 had the smallest decline,followed by MC812,showing good heat resistance,while Zhengdan958 had the largest decline in the length of tassel,but the amount of pollen was the largest due to the large number of tassel branches.Xianyu335 has fewer male panicle branches,a large decrease in male panicle length,the least amount of pollen and low activity.Among the parental materials,Jing2416 had a large amount of total loose pollen and strong pollen vitality under high temperature treatment,with the smallest decline,only 4.50 and 3.98 percentage points.Compared with the control,the interval of loose pollen silking(ASI)was prolonged by 1.6d under high temperature stress.The decrease in male spike length is manifested as Zhengdan958＞Xianyu335＞MC812＞Jingnongke728.Zhengdan958 had the largest decrease in male spike length,but had more branches and the largest pollen yield;Xianyu335 has fewer branches of male spikes,a significant decrease in male spike length,the least pollen quantity,and the lowest activity;Jing 2416 has a large amount of loose pollen and strong pollen vitality,with the smallest decrease(only 4.50%and 3.98%).[Conclusion]High temperature stress before and after anthesis has a significant impact on the grain yield,male and female ear development process,pollen activity and filament microstructure of the tested maize varieties.Under high temperature stress at this stage,the decline of yield and pollen activity of Jingnongke728 and MC812 is significantly less than Xianyu335,showing higher single ear yield and heat tolerance.By comparing the heat resistance of the parental inbred lines of the tested maize hybrids,it was found that the heat resistance of the paternal inbred lines was better than that of the maternal inbred lines.The male panicle branch and length of the parent material Jing2416 decreased slightly,the amount of pollen was large,the pollen activity was high,the filaments were hairy,the ability to capture pollen was strong,the single panicle yield was high,and the heat resistance was the best.Therefore,in the planting area with frequent high temperature and heat damage,selecting maize varieties such as Jingnongke728 can achieve stable and high yield;and during the maize breeding process,we should pay more attention to the utilizing of the higher temperature resistant inbred such an Jing2416 and then combination higher temperature maize varieties.
high temperaturemaizeparental inbred linesheat resistance
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