硒对镉胁迫下不同基因型油菜镉积累、光合特性及抗氧化活性的影响

摘要

A hydroponic experiment was performed to investigate the mechanisms of Se mitigation of Cd toxicity in oilseed rapes. The effects of 0.3 mg·L-1 Se on Cd accumulation, photosynthetic characteristics and activities of antioxidant enzymes in two genotypes of rape(WH-19 and WH-95)under 0.5 mg·L-1 Cd stress were studied. The results showed that:Se application significantly decreased Cd contents in roots, stems and leaves in WH-95 with the decrease rates of 8.51%, 34.61%and 46.14%respectively compared with only Cd treatment, while no significant differences were observed in WH-19. Se greatly increased the net photosynthetic rate and the transpiration rate by 18.96%and 22.77%respectively, and significantly decreased the intercellular CO2 concentrations to 72.61%in WH-19 compared with only Cd treatment. As for WH-95, only the intercellular CO2 concentrations were significantly decreased to 85.96%under Se application, while other three pho-tosynthetic characteristics showed no greatly changed;Se significantly decreased SOD activity in WH-19 by 29.03%, while no significant differences were observed in the activities of CAT and POD;For WH-95, 9%increase was found in CAT activity, while no marked differ-ences were found in the activities of SOD and POD compared with only Cd treatment. Overall, Se alleviated Cd toxicities in the two oilseed rapes by enhancement of the photosynthetic system. However, the Cd accumulation and the antioxidative system showed differenct responses to Cd stress.%为研究硒对油菜镉毒害的缓解作用,采用水培实验研究了硒(0.3 mg·L-1)对镉(0.5 mg·L-1)胁迫下不同基因型("WH-19"和"WH-95")油菜镉含量、光合特性及抗氧化活性的影响.结果表明:与镉单施相比,硒的添加并未显著改变"WH-19"油菜根、茎、叶中镉含量,显著降低了"WH-95"油菜根、茎、叶中镉含量,分别降低了8.51%、34.61%和46.14%;"WH-19"的净光合速率和蒸腾速率显著提高,分别提高了18.96%和22.77%,气孔导度略有提高,胞间二氧化碳浓度显著降低至镉单独作用时的72.61%;"WH-95"的净光合速率和蒸腾速率略有提高,气孔导度无显著变化,胞间二氧化碳浓度显著降低为镉单独作用时的85.96%;"WH-19"的SOD活性显著降低了29.03%,CAT活性和POD活性无显著变化;"WH-95"的CAT活性略有提高,为镉单独作用时的1.09倍,SOD活性和POD活性无显著变化.硒对镉胁迫下不同基因型油菜镉含量和抗氧化酶活性的影响不同,而对2个品种油菜光合特性的影响趋势基本一致,不同基因型油菜的光合能力均得到提高,缓解了镉对油菜的毒害.