研究了UV-C辐射下短期和长期脱落酸(ABA)处理对小麦幼苗CO2同化作用、羧化效率、光合CO2响应以及抗氧化酶活性等的影响.结果表明,在无UV-C辐射情况下,短期和长期ABA处理能提高光合速率,比对照增加14.69%和20.46%,降低气孔导度,比对照降低14.74%和17.31%,但对胞间CO2浓度和羧化效率影响不大.当受到UV-C辐射时,光合速率、羧化效率、气孔导度和胞间CO2浓度逐渐降低.长期ABA处理变化最小,其次为ABA短期处理,对照降低最大.ABA处理能够提高小麦光合对CO2的响应,UV-C辐射抑制光合对CO2的响应.ABA处理能够提高小麦抗氧化酶(CAT、SOD、POD)活性而降低MDA含量.在UV-C辐射下,CAT活性先升高随后降低,在辐射处理1h时活性达最大值,ABA处理的SOD和POD活性先升高后降低,且ABA长期处理比短期处理增加明显,对照则逐渐降低.ABA处理可能通过提高小麦CO2同化作用和抗氧化酶活性增强对UV-C胁迫的抗性,且ABA长期处理比短期处理效果更明显.
This paper studied the effects of short- and long term abscisic acid (ABA) treatments on the CO2 assimilation (Pn), carboxylation efficiency (CE), response of Pn to CO2, and antioxidant enzyme activities of wheat seedlings exposed to UV-C. The results showed that under no UV-C, short- and long term ABA treatments increased Pn by 14.69% and 20.46%, and decreased stomatal conductance (Gs) by 14.74% and 17.31%, respectively, compared to the control, while no effects were observed on intercellular CO2 concentration (Ci) and CE. Under UV-C, the Pn, CE, Gs and Ci decreased, with the least decrease in long term ABA treatment, less in short term ABA treatment, and the most in control. ABA could increase the response of Pn to CO2, while UV-C inhibited it. In ABA treatments, antioxidant enzyme activities were enhanced, while MDA content was decreased. Under UV-C, CAT activity increased first, reached its maximum after 1 h, and decreased then. The activities of SOD and POD in ABA treatments increased first and decreased then, with the greater increase in long term ABA treatment than in short term ABA treatment, while those in the control decreased. It was suggested that through enhancing Pn and antioxidant enzyme activities, ABA could enhance the resistance of wheat to UV-C, and long term ABA treatment had better effects than short term ABA treatment.