外源褪黑素对低温弱光胁迫下辣椒叶绿素荧光和抗氧化系统的影响

以陇椒10号为试验材料，待辣椒幼苗长至6片真叶时，叶面喷施不同浓度褪黑素(MT)溶液0(T1)、50(T2)、100(T3)、150(T4)、200(T5)和250(T6)μmol·L^-1,研究不同浓度褪黑素对辣椒幼苗低温弱光胁迫条件下叶绿素含量、叶绿素荧光参数、相对电导率、可溶性糖、丙二醛(MDA)含量以及抗氧化酶活性的影响。结果表明：在低温弱光胁迫下(15℃/5℃,100μmol·m^-2·s^-1)处理7 d后，与T1相比，外源喷施100μmol·L^-1的褪黑素溶液(T3)后总叶绿素含量和可溶性糖含量分别提高了25.72%、52.88%,实际光化学效率Y(Ⅱ)、光化学猝灭系数qP、光化学猝灭qL分别显著增加了43.79%、36.99%和33.88%,超氧化物歧化酶(SOD)、超过氧化氢酶(CAT)活性显著提高了66.31%、56.65%,超氧阴离子含量、相对电导率分别显著降低了48.40%、17.54%。综上所述，叶面喷施褪黑素能通过提高低温弱光胁迫下辣椒叶片叶绿素含量、叶绿素荧光特性及抗氧化能力...

Effects of exogenous melatonin on chlorophyll fluorescence and antioxidant system of pepper (Capsicum annuum L.) under low temperature and low light stress

In this study, pepper variety Longjiao 10 was used as the material. The different concentrations of melatonin including 0 (T1), 50 (T2), 100 (T3), 150 (T4), 200 (T5), 250 (T6) μmol·L^-1 were sprayed at seedling stage, and chlorophyll content, chlorophyll fluorescence parameters, relative conductivity, soluble sugar, malondialdehyde (MDA) content, and antioxidant enzyme activity of pepper seedlings under low temperature and low light stress were determined. The results showed that 7 day after treatment with low temperature and low light stress (15 ℃/5 ℃, 100 μmol·m^-2·s^-1), after exogenous application of 100 μmol·L^-1 melatonin solution (T3), total chlorophyll content and soluble sugar content increased by 25.72% and 52.88% respectively, compared with T1. The actual photochemical efficiency Y(Ⅱ), the photochemical quenching coefficient qP, photochemical quenching qL increased by 43.79%, 36.99% and 33.88%, separately. The superoxide dismutase (SOD), catalase (CAT) activities were increased significantly by 66.31%, 56.65% while the superoxide anion content and relative conductivity decreased by 48.40% and 17.54%, respectively. In summary, the application of melatonin on the leaves of pepper under low temperature and low light stress could improve the chlorophyll content, chlorophyll fluorescence characteristics and antioxidant capacity, and increase the content of soluble sugar to increase the stress resistance of the plants. The best melatonin concentration was 100 μmol·L^-1.