供氮水平对香根草光合特性和抗氧化酶活性的影响

Effects of Different Nitrogen Supply on Photosynthesis,Antioxidant Enzymes in Vetiver Leaves

通过水培试验,研究了0、1、8和16mmol.L-14个供氮水平下香根草叶片净光合速率(Pn)、叶绿素荧光参数、抗氧化酶类活性和MDA、脯氨酸含量的变化。结果表明,随着氮浓度的增加,香根草叶片Pn、PSⅡ最大光化学效率(Fv/Fm)、PSⅡ电子传递量子产率(ФPSⅡ)、光化学猝灭系数(qP)、非光化学猝灭系数(NPQ)、超氧化物歧化酶(SOD)和过氧化物酶(POD)活性先升高后降低,8mmol.L-1氮浓度时达最大,16mmol.L-1氮浓度时最小,而1mmol.L-1与8mmol.L-1氮浓度时相比差异不显著;随着氮浓度的增加,过氧化氢酶(CAT)活性、丙二醛(MDA)含量则先下降后升高;游离脯氨酸(Pro)含量上升,说明香根草叶片在低氮情况下能保持较高的Fv/Fm、ФPSⅡ、qP和抗氧化酶活性。

The effects of four nitrogen （N） treatments （0, 1, 8 or 16 mmol · L^-1） on the photosynthesis, antioxidant defense systems and lipid peroxidation in vetiver leaves were studied in a solution culture experiment. The results show that the net photosynthetic rate （Pn）, the maximum photochemical efficiency of PS Ⅱ reaction centres （Fv/Fm）, quantum efficiency of PS Ⅱ electron transport （ФPsn）, photochemical quenching （qP）, non-photochemical quenching （NPQ）, superoxide dismutase （SOD） and peroxidase （POD） activities rose firstly and then declined when N concentrations increased from 0 mmol · L^-1 to 16 mmol· L^-1. They reached heighest at 8 mmol ·L^-1 N and were minimum at 16 mmol · L^-1 N. During the two types of treatments （1 and 8 mmol· L^-1 N）, Pn, Fv/Fm, ФPS Ⅱ, qP, NPQ, SOD and POD activities did not show difference significantly. Catalase activity and malondialdehyde （MDA） content reduced firstly and then enhanced while proline （Pro） accumulated with increasing N supply. These results indicate that vetiver leaves have a higher Fv/Fm,ФPSⅡ , qP and activities of antioxidant enzymes under low nitrogen conditions.