不同成熟度玉米叶片光合生理对高温胁迫的响应特征及其基因型差异

摘要

In order to explore the photosynthetic physiological response character to heat stress of maize leaves,the maize hybrids ZD958 and XY335 were used as materials,and heat stress was imposed from the 9th leaf stage to tasseling stage in 8:30-17:30 in the field conditions,the photosynthetic parameters,the activities of RuBPCase,PEPCase and sucrose phosphate synthase (SPS) were studied.The results showed that compared with control (normal condition),under heat stress,the leaf SPAD value decreased significantly except the juvenile leaf of ZD958,net photosynthesis rate (Pn),evaporation rate (Tr),and stomatal conductance(Gs) were decreased significantly with a larger reduction extent of maturity leaves than juvenile leaves,intercellular CO2 concentration(Ci) increased more in juvenile leaves than in maturity leaves,the maximum photochemical efficiency of PSⅡ was decreased with the juvenile leaves decreasing significantly,RuBPCase and SPS activities of maturity leaves of ZD958 and XY335 and the juvenile leaves of XY335 were decreased significantly,PEPCase activities of maturity leaves of ZD958 and the juvenile leaves of ZD958 and XY335 increased significantly.In conclusion,heat stress resulted in a significant decrease of photosynthesis capacity of maize leaves,and the influence of heat stress on maturity leaves was larger than that on juvenile leaves.ZD958 was more tolerant to heat stress than XY335.%为了探索玉米叶片光合生理对高温胁迫的响应特征,以郑单958(ZD958)和先玉335(XY335)为材料,从第9片叶展开期至抽雄期,每天8:30-17:30进行大田人工模拟增温试验,研究了不同成熟度玉米叶片的光合参数和RuBP羧化酶、PEP羧化酶、蔗糖磷酸合成酶(SPS)活性的变化.结果表明,高温胁迫下,叶片的SPAD值除了ZD958幼嫩叶片略高于对照(自然生长)外,其余处理均显著低于对照;净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)均显著下降,且成熟叶片的下降幅度高于幼嫩叶片;胞间CO2浓度(Ci)增加,幼嫩叶片的增加幅度高于成熟叶片;成熟叶片和幼嫩叶片的PSⅡ最大光化学效率均下降,且幼嫩叶片的下降幅度达到显著水平.高温胁迫下,2个品种成熟叶片和XY335幼嫩叶片的RuBP羧化酶和SPS活性显著降低,ZD958成熟叶片和2个品种幼嫩叶片的PEP羧化酶活性显著增加.可见,高温胁迫显著降低了玉米叶片的光合性能,且对成熟叶片的影响大于幼嫩叶片,对XY335的影响大于ZD958.