芘对红树植物桐花树幼苗生理生化指标的影响

Effects of pyrene on physiological and biochemical indexes of mangrove Aegiceras corniculatum seedlings

研究了一种典型多环芳香烃—芘处理(浓度为20 mg·kg^(–1))及不同处理时间对红树植物桐花树(Aegiceras corniculatum(L)Blanco)生理生化指标的影响。结果表明,芘处理显著提高了桐花树的株高(7.43%)和生物量(38.55%),而对地径和叶数无显著影响;随生长时间延长,芘处理植株和对照(CK)植株的株高、地径、叶片数和生物量均显著增加。芘处理对桐花树的叶绿素(Chl)含量不产生影响;但随生长时间延长,Chla和Chla/b显著降低,而Chlb和Chl(a+b)显著下降后在150 d时又恢复至最初水平。芘处理对桐花树的净光合速率P_n和气孔导度G_s影响不大,却显著提高了其蒸腾速率E和胞间CO_2浓度C_i。添加芘显著提高了桐花树超氧化物歧化酶(SOD)、谷胱甘肽-S-转移酶(GST)、过氧化物酶(POD)等抗氧化系统酶活性及丙二醛(MDA)的含量,使其分别提高了9.23%,94.30%,70.09%和27.40%。随生长时间延长,SOD、GST和POD显著升高,而MDA含量在第50天时显著升高后在第100天和第150天又相继显著下降。上述结果表明,添加浓度为20 mg·kg^(–1)的芘处理不会对桐花树的光合作用产生显著影响,而显著促进其生长和生物量积累;此浓度下的芘处理提高了桐花树的抗氧化酶活性,说明桐花树对芘胁迫具有一定的耐受性。

In the present work,the physiological and biochemical responses of Aegiceras corniculatum seedlings to pyrene(Pyr)contamination(20mg·kg–1)were studied.Results showed that the height,ground diameters,leaves and biomass of A.corniculatum all significantly increased with treatment time,especially the height and biomass were significantly enhancedunder Pyr treatment by7.43%and38.55%,respectively.The chlorophyll(Chl)content of A.corniculatum was found nodifference under Pyr treatment.Chla,Chlb,Chl(a+b)and Chla/b initially declined significantly with treatment,while Chlband Chl(a+b)returned to the initial content later.The transpiration rate and intercellular CO2concentration were enhancedsignificantly while no effects were observed on net photosynthetic rate and stomatal conductance under Pyr treatment.Antioxidant enzyme activities of contaminated A.corniculatum,including superoxide dismutase(SOD),glutathione-stransferase(GST),peroxidase(POD)and content of malondialdehyde(MDA)significantly increased by9.23%,94.30%,70.09%and27.40%,respectively.SOD,GST and POD all increased significantly with time while MDA declined on the100thand150th day.In summary,20mg·kg–1Pyr contamination had no significant effects on the photosynthesis while a promotionon the height and biomass of A.corniculatum seedlings.The additional enhancement of antioxidant enzyme activities of A.corniculatum indicated its potential tolerance to Pyr contamination.