Study On Analysis And Control Technology Of Postharvest Diseases Of Table Grapes In Liyang Plain

In recent years, the grape industry is developing rapidly in Liyang plain in Hunan. The table Grapes in Hunan has suffered substantial post-harvest losses influenced by the climate, seasonality and regionality. To improve the storage quality of grapes, extend the shelf life of grapes and reduce the post-harvest losses, the study investigated and analyzed the main diseases of table grapes in Liyang plain. This study use Red globe grapes in Liyang plain as test materials. The study isolated the major pathogenic fungi FLJ-01～FLJ-06 during the post-harvest storage period of Red globe grapes in Liyang plain. The Study choosed the konjac purified powder concentration, phytic acid concentration, sodium hexametaphosphate concentration to do the response surface experiment analysis after the research on bacteriostatic effect of several fresh keeping agents and selected an antimicrobial preservative formula and verify its effect in the storage period of grapes. Main results were as follows.(1)The kinds of disease of table grapes in Liyang plain were:bird’s eye rot, alternaria rot, ripe rot, white rot, downy mildew, powdery mildew, gray mold, fruit cracking, root knot, virus disease, penicilliosis, soft rot, cross-linking spore mildew rot and bud branch mildew rot. Multiple diseases were:downy mildew, gray mold, fruit cracking, penicilliosis and soft rot. Comprehensive the three main diseases of downy mildew, gray mold and fruit cracking, the grape varieties of strong disease resistance were Karen seedless, Ruby and Victoria.(2)There were six major pathogenic fungi of the grapes during the post-harvest storage period in Liyang plain. They were preliminary identificated as Aspergillus flavus, Aspergillus niger, Penicillium, Alternaria alternata, Fusarium and Botrytis cinerea.(3)The minimal inhibitory fungal concentration of konjac purified powder to the mixed fungi suspension was 10mg/mL. The minimal inhibitory fungal concentration of phytic acid to the mixed fungi suspension was 0.625mg/mL. The minimal inhibitory fungal concentration of sodium hexametaphosphate to the mixed fungi suspension is 0.25mg/mL. The antimicrobial preservative optimal formula was: 0.74% konjac purified powder+0.06% phytic acid+0.02% sodium hexametaphosphate+0.2% calcium chloride.(4)Antimicrobial preservative effect of keeping fresh is better than the other treatment group, significantly better than CK group. Storaged after 60 days, antimicrobial preservative treatment of grapes weightlessness rate was lower than the control group 10.20%, also threshing rate was lower than the control group 22.42%, healthy fruit rate was higher than the control group 40.24%, the respiration intensity was lower than the control group 3.33 mgCO2/kg · h, relative electric conductivity was lower than the control group 17.07%, malondialdehyde content was lower than the control group 5.35μmol/g, the peroxidase activity was higher than control group 7.47U/gmin, superoxide dismutase activity was higher than control group 37.62U/g, electron microscope scanned the grapes’ endocarp, the endocarp was still smooth membrane-like structure, it’s better to keep the quality of the grapes.