外源褪黑素对小麦幼苗生理及光合荧光特性的影响

o explore the effects of different concentrations of melatonin on physiological andphotosynthetic fluorescence characteristics of wheat seedlings. The growth morphology,photosynthetic, fluorescence parameters and antioxidant enzyme activity of wheat seedings treatedwith different concentrations of melatonin were determined by using Liangxing 99 asexperimental material. The results were as follows: (1) 0.1 molL-1 melatonin significantly increased the photosynthetic capacity of wheat plants, Chlorophyll a (Chl a), Chlorophyll b (Chl b)and Chlorophyll (a+b) [Chl (a+b)] increased to the maximum value when melatonin concentrationwas 0.1 molL-1. Chlorophyll fluorescence parameters include parameters of quantum yield ofregulated energy dissipation Y (NPQ), the electron transport rate (ETR) and non photochemicalquenching (NPQ) also reaches the maximum at 0.1 molL-1. The PS maximum photosyntheticefficiency (Fv/Fm) and maximum photochemical conversion potential (Fv/Fo) decreased with theincrease of melatonin concentratio. Photochemical quenching (qL) decreased first and thenincreased with the increase of melatonin. (2) Compared with CK (0 molL-1), low melatoninconcentration significantly decreased peroxidase (POD) activity in wheat and decreased catalase(CAT) activity in wheat leaves, high melatonin concentration significantly increased POD activityin wheat. Low concentration of melatonin treatment significantly reduced the catalase (CAT)activity in wheat leaves by compared with CK. The content of malondialdehyde (MDA) in wheatroots decreased firstly and then increased with the increase of melatonin concentration. Inconclusion, it suggested that appropriate melatonin treatment can promote the growth of wheatand maintain the photosynthetic capacity of wheat at a high level. Enzymes including POD andCAT can also regulate oxidative stress induced by different concentrations of melatonin in wheatseedlings. This study laid a foundation for further understanding the regulatory mechanism ofmelatonin in wheat.