Effects of Exogenous Melatonin on Helianthus annuus L.Under NaCl Stress
Salt stress is one of the abiotic stresses that affect crop yield and quality.Melatonin can effective-ly enhance a plant's response to salt stress.In this study,Helianthus annuus L.was chosen as the subject,and a stress concentration of 0.25 mol/L NaCl was selected.The physiological regulation mechanism of exogenous melatonin on sunflower seed germination under salt stress was investigated by assessing seed germination index,membrane lipid peroxidation degree,osmotic adjustment substance content,and antioxidant enzyme activity.The results showed that with the increase of melatonin concentration,the germination potential,germination rate,germination index,and soluble protein content of seeds increased first and then decreased,with the optimal con-centration at 25 μmol/L.The proline content increased compared with the control,with the optimal effect at 100 μmol/L.The content of MDA decreased compared with the control,and the inhibitory effect of 25 μmol/L was the most significant.Different concentrations of exogenous melatonin significantly increased the activities of SOD,POD,and CAT in seeds,with the most significant effect at 25 μmol/L.In summary,25 μmol/L melatonin can be used as an effective pretreatment measure for sunflower seed germination under NaCl stress.This study lays a foundation for the utilization of melatonin and the regulation of Helianthus annuus L.cultivation.
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