Research Of Improving The Quality Of Mulberry Fruit Using The Exogenous Elicitors

Mulberry is one of the berries which has very high nutritional and economic value.Mulberry is highly vulnerable to pathogen infection during the flowering season. Moreover,mulberry fruits are perishable after picked. The production of mulberry fruits has decreased.The quality of mulberry has been seriously affected. As the expansion of the needs of the fresh mulberry in domestic and international market, improving the quality of the mulberry has got more and more people’s attention. To study the overall way of improving the quality of mulberry, this paper concerns mainly: 1. disease control of mulberry fruits during flowering season. 2. active metabolite accumulation of mulberry fruits before harvest. 3.postharvest storage control of mulberry fruit. The result is as follows:This paper chose the mulberry varieties ‘zhong sang5801’ for experiments. First we studied the biocontrol effects of Trichoderma against mulberry sclerotium disease. 48 strains of Trichoderma were isolated from mulberry rhizospheric soil. Then we observed the morphology of Trichoderma under a light microscope. Trichoderma can be divided into sect. Trichoderma, sect. Pachybasium, sect. Longibachiatum, and sect. Hypocreanum according to the Bissett classification system. 20 Trichoderma strains which has high degree of powerfully occupy space against the pathogen was screened by confrontation culture method. For PCR amplification, the ITS primers amplified a single fragment. A blast analysis of the sequence indicated that the amplified gene fragment shared over 99 %similarity with the ITS gene sequences from Trichoderma spp.. Evolutionary tree construction were performed. Then we studied the effect of 20 Trichoderma metabolites on the mycelial growth of the pathogen using cellophane papers. A field trial was carried out to investigate the field efficacy of Trichoderma belong to 3 genus with the best antagonistic potential. Field spraying experiments showed that:Tr16, Tr 50 Trichoderma fermentation liquor got better controlling effect of mulberry sclerotium disease.To study the 4 different elicitors on the effect of active mulberry metabolisms accumulation, we sprayed different concentration of chitosan, coronatine, Phellinus linteus polysaccharides, Trichoderma fermentation solution before harvest. Results showed that the 4 elicitors have effects on the accumulation of total polyphenol and total flavonoids of mulberry fruits. But they had little effect on the content of total sugar. After three times of spraying, the effect of 4 elicitors on the total polyphenol is Tr16 Trichoderma fermentationsolution > 0.5 g/L chitosan > 0.01 μmol/L coronatine > 0.1 g/L Phellinus linteus polysaccharides > CK. The effect of 4 elicitors on the total flavonoids is Tr16 Trichoderma fermentation solution > 0.1 g/L chitosan > 0.01 μmol/L coronatine > 0.1 g/L Phellinus linteus polysaccharides.At last, to study the effect of the storage quality of fruit, we treated mulberry fruits with the 4 different elicitors. Results showed that Trichoderma fermentation liquor and chitosan have good potential in mulberry fruits’ s postharvest decay control. Because they have good antifungal performance. Chitosan can form the film on the fruit surface and inhibit respiration of mulberry, reduce moisture loss. Tr16 Trichoderma fermentation solution, 0.1g/L chitosan, 0.001 μmol/L coronatine treatments can keep the mulberry fruit sugar content.Tr16 Trichoderma and CTS treatments can effectively delay the decline of mulberry total phenol content. The Tr16 Trichoderma fermentation diluted 10-folds and the original fermentation fluid, 0.1g/L CTS, coronatine treatments can better keep the flavonoids content.This study first discusses the feasibility of the exogenous elicitors used to improve mulberry overall quality. We aimed at provide the theory and practice basis about the preand postharvest diseases control and the accumulation of active metabolites.