Study on Resistance to Alternaria Rot of Postharvest Winter Jujube Induced by Melatonin

In the present research, the postharvest winter jujube was treated with 0, 2, 20, 200 μmol/L melatonin conjugated Alternaria alternate, aiming to investigate the nosotropic effects of melatonin on Alternaria rot in postharvest winter jujube. Results showed that melatonin treatments could inhibit the expansion of disease spot diameters, reduce the decay indices and weight loss rates of winter jujube, and suppress the increase of respiration rates and relative electrical conductivity, and maintain the MDA contents at a low level. In addition, melatonin treatments could also improve the activities of phenylalanine ammonia-lyase（PAL）, chitinase（CHI）, β-1,3-glucanase（ GLU）, catalase（ CAT）, peroxidase（ POD） and the contents of disease-resistance related substances（flavonoids, total phenols and lignin）. These results suggested that melatonin could improve the anti-black spot ability of postharvest winter jujube by activating resistance-related enzymes and improving anti-fungal substances contents, which could be used as a potential activator to improve the resistance to postharvest pathogens, thereby applied for the prevention and control of postharvest fruits decay.