高温胁迫对玉米杂交种及其亲本自交系光合特性、保护酶活性和产量的影响

Effects of high-temperature stress on photosynthetic characteristics,protective enzyme activity,and yield of maize hybrids along with their parental inbred lines

研究并明确高温胁迫对玉米杂交种及其亲本自交系叶片光合性能、产量性状等的影响,以期为耐高温玉米品种选育和推广提供理论依据。以‘京农科728’‘MC812’‘先玉335’和‘郑单958’及其亲本自交系为试验材料,于花期前后(大喇叭口期—吐丝后7 d)对其进行高温胁迫(高温胁迫15 d)处理,研究高温胁迫对不同基因型玉米杂交种及其亲本自交系叶绿素相对含量、光合特性、最大光化学效率(F_(v)/F_(m))、保护酶活性、产量及其产量构成要素的影响。结果表明:1)与大田对照相比,花期前后高温胁迫下不同杂交种及其亲本自交系的叶绿素相对含量、净光合速率、气孔导度和F_(v)/F_(m)均呈降低趋势,杂交种以‘京农科728’降幅最小,亲本自交系以‘京2416’降幅最小。胞间CO_(2)浓度和蒸腾速率则均呈升高趋势,杂交种以‘京农科728’增幅最小,亲本自交系以‘京2416’增幅最小。2)花期前后高温胁迫导致玉米杂交种及其亲本自交系的穗位叶磷酸烯醇式丙酮酸羧化酶(PEPCase)、核酮糖-1,5-二磷酸羧化酶(RuBPCase)、过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性呈降低趋势。3)花期前后高温胁迫降低了玉米杂交种及其亲本自交系的穗行数和行粒数,进而导致产量下降,杂交种‘京农科728’‘MC812’‘先玉335’和‘郑单958’产量分别降低3.18%、5.00%、50.61%和9.50%;亲本自交系中,‘京2416’的穗行数、行粒数和产量降幅最小,而‘PH6WC’产量降幅最大。由此可见,花期前后高温胁迫下‘京农科728’‘MC812’及其父本自交‘京2416’具有较高的叶绿素相对含量、光合能力和保护酶活性,产量受高温影响较小,具有较好的耐热性。

The Huang-Huai-Hai summer maize region is a dominant maize producing area in China.Adverse climates,such as hightemperatures and heat damage,occur frequently during maize growing season and have a great impact on maize production.The effects of high-temperature stress on leaf photosynthetic performance and yield traits of maize hybrids as well as their parent inbred lines were studied to provide a theoretical basis for the breeding and popularization of high-temperature-tolerant maize varieties.‘Jingnongke728’‘MC812’‘Xianyu335’‘Zhengdan958’and their parental inbred lines were used,high-temperature treatments from the bell-mouthing stage to 7 d after silking were conducted,and the effects of high-temperature stress on the relative content of chlorophyll,photosynthetic characteristics,F_(v)/F_(m),photosynthetic enzyme activity,yield and yield components were studied.Compared to field control,the relative chlorophyll content,net photosynthetic rate,stomatal conductance,and F_(v)/F_(m)of different hybrids and their parent inbred lines decreased under high-temperature stress pre-and post-flowering.The decreases of hybrid‘Jingnongke728’and parent inbred line‘Jing2416’were the smallest.The intercellular CO_(2)concentration and transpiration rate displayed an increasing trend,with‘Jingnongke728’and‘Jing2416’having the smallest increase.The activities of phosphoenolpyruvate carboxylase,ribulose 1,5-diphosphate carboxylase,catalase,and superoxide dismutase in the ear leaves of maize hybrids and their parent inbred lines decreased under high-temperature stress pre-and post-flowering.High-temperature stress pre-and post-flowering reduced ear row number,kernel per row in maize hybrids and their parent inbred lines,decreasing yield.The yields of hybrids‘Jingnongke728’‘MC812’‘Xianyu335’and‘Zhengdan958’decreased by 3.18%,5.00%,50.61%,and 9.50%,respectively.Among the parent inbred lines,‘Jing2416’had the smallest decrease in ear row number,kernel per row and yield,whereas the yield of‘PH6WC’had the largest decrease.‘Jingnongke728’‘MC812’and their male parent‘Jing2416’had higher relative chlorophyll content,photosynthetic capacity,and protective enzyme activity under high-temperature stress pre-and post-flowering,and their yield was less affected by high-temperature;thus,they have better heat tolerance.