低温胁迫下北方强冬性区甘蓝型冬油菜的低温光合生理特征

Physiological and photosynthetic characteristics of winter rapeseeds under low temperature stress in northern strong winterness region

【目的】探讨低温胁迫对甘蓝型冬油菜生理及光合特征的影响,为甘蓝型冬油菜在北方旱寒区种植提供理论依据.【方法】以TSG10、天油2266、天油2288和Vision 4个甘蓝型冬油菜品种为材料,低温处理(-4℃)后,测定幼苗光合生理特征变化;并采用电子显微镜观察叶绿体超微结构变化.【结果】低温胁迫下,弱抗寒品种Vision受害症状较重,叶片萎蔫,叶缘出现大小不同水渍状冻斑;强抗寒品种TSG10受害症状明显较轻.低温胁迫下,甘蓝型油菜各品种渗透调节物质含量、抗氧化酶活性均明显升高;但与Vision相比,强抗寒品种TSG10渗透调节物质含量,比弱抗寒品种高29.6%~34.5%,抗氧化酶活性高37.6%~50.4%,相对电导率和丙二醛含量分别比弱抗寒品种低34.5%和37.5%.低温胁迫后,甘蓝型油菜叶片Gs、Tr、Pn均明显降低,表明低温胁迫下,气孔限制是引起甘蓝型冬油菜光合减弱的主要因素;低温处理后,强抗寒品种TSG10较好保持了叶绿体膜的完整性和基质片膜的连续性,其Pn下降幅度也最小,为69.5%,抗寒较弱的品种下降幅度在83.6%~93.0%之间.【结论】低温胁迫下,甘蓝型冬油菜强抗寒品种有较高过氧化物清除能力和较强渗透调节能力,叶绿体膜结构保持较为完整,净光合速率相对较高.

【Objective】The effects of low temperature stress on physiological and photosynthetic characteristics of winter rapeseeds(Brassica napus)were studied to provide a theoretical basis for winter rapeseeds growing in the cold and arid areas of northern China.【Method】Four winter rapeseeds cultivars were used to determine the changes of photosynthetic and physiological characteristics of seedlings and the ultrastructure of chloroplast was observed with electron microscope under low temperature treatment(-4℃).【Result】Cultivar Vision suffered more severe injury with the symptoms of leaf wilting and different sizes of water-stained frozen spots on leaf edge,while the injury to cultivar TSG10 was less under low temperature treatment.Both osmotic adjustment substance contents and antioxidant enzyme activity showed a significant increasing trend.Compared with Vision,the osmotic substance content of strong cold-resistant cultivar TSG10 was 29.6%to 34.5%higher than that of weak cold-resistant cultivar,and the activity of antioxidant enzymes was 37.6%to 50.4%higher.The relative conductivity and MDA content were 34.5%and 37.5%lower than those of weak cold-resistant cultivars,respectively.Gs,Tr and Pn in leaf significantly decreased under low temperature stress,indicating that stomatal limitation was the main factor resulting in the weakening of photosynthesis.After low temperature treatment,the strong cold-resistant cultivar TSG10 well maintained the integrity of the chloroplast membrane and the continuity of the matrix membrane,and its Pn decreased by 69.5%,however,the Pn of the weak cold-resistance cultivars decreased by 83.6%to 93.0%.【Conclusion】Under low temperature stress,the strong cold-resistant rapeseeds cultivars performed higher peroxidation scavenging ability and strong osmotic regulation ability,the chloroplast membrane structure was relatively intact,and the net photosynthetic rate was relatively high,which were the important physiological basis of strong cold resistance.