Study On Improving The Fruit Quality And Reducing The Occurrence Of Diseases Of Table Grapevines By Shelter-rain Cultivation

Shaanxi Province located in the hinterland of China belongs to a continental monsoon climate with an annual average temperature and rainfall being 12.7℃ and 700 mm,respectively,from June to August during an important period for the grapevine growth and development.However,the overcast and rainy days make grape downy mildew,gray mold,acid rot and other fungal diseases frequently happen,which is not conducive to the growth of grape plants and the accumulation of fruit sugar,resulting in a substantial decline in grape yield and quality.These seriously hinder the development of grape industry in Shaanxi Province.Therefore,the experiments are conducted to explore the influence of shelter-rain cultivation and fruit bagging technology on the growth and development,fruit quality and disease occurrence of table grapes in Shaanxi Province.In this study,we obtain the optimal cultivation mode and the best fruit bags through the statistics and comparison of the relevant physiological index and growth parameters under different cultivation and bagging modes,resulting in improving the growth and development,enhanced the fruit quality and reduced the occurrence of disease in table grapevines,which provides a theoretical basis for the promotion and application of rain-proof cultivation modes in Shaanxi Province.The main findings are as follows:1.Generally,the V.vinifera L.× V.labrusca resistance to downy mildew is significantly better than that of V.vinifera L.in the natural conditions.The main cultivars,‘Hutai No.8’ and‘Summer Black’,have a strong resistant capability to downy mildew,though the diseased leaves rates is 67.27% and 75.47%,respectively.And the rate of diseased leaves of ‘Red Globe’and ‘Flame Seedless’ is as high as 100%,without intact leaves.2.Shelter-rain cultivation reduces Pn and Gs in these table grapevines,while increases its Tr.It also decreases its NPQ,and augments the Fv/Fm and Y(Ⅱ).The contents of chlorophylla,chlorophyllb,total chlorophyll,sucrose and starch in the leaves grown in shelterrain cultivation are all higher than those in open-fields cultivation,especially in ‘Red Globe’and ‘Flame Seedless’,except for some unexpectedness.The chlorophyll a/b ratio in all cultivars leaves is significantly higher under open-field cultivation than that undershelter-rain cultivation.In addition,shelter-rain cultivation promotes the lengthening and thickening of grape branches,and significantly improves the quality of grape winter buds.3.Shelter-rain cultivation significantly increased the grain and berry weight,fruit size and CIRG value and significantly decreased the C* in ‘Hutai No.8’ and ‘Summer Black’grapes,while no remarkable influence on ‘Flame Seedless’ grape.Moreover,shelter-rain cultivation also significantly increased the soluble solid content and solid-acid ratio,but had less effect on the total acid content in all three grapevine berries.And the decrease of organic acids was significantly improved with shelter-rain cultivation in ‘Hutai No.8’ and ‘Summer Black’ grapes.Additionally,fruit bagging brought effect on the quality of grapevine table fruits at varying degree,and there were significant differences depending on the various cultivation patterns.According to the principal component analysis,red non-woven bags have the best effect on improving the fruit of table grapevines under shelter-rain cultivation.4.Shelter-rain cultivation significantly reduced the diseased leaf rate and disease index of grape leaves downy mildew,especially for ‘Red Globe’ and ‘Flame Seedless’,which were reduced by 56.21% and 30.06,57.68% and 41.61,respectively.Furthmore,this cultivation mode markedly improves the disease resistance level of grapevines,reduces the grape leaves SA contenst,and dramatically decreases the disease rate and disease index of fresh grapes.And red non-woven bags have the largest decreased rates under shelter-rain cultivation.In summary,shelter-rain cultivation can effectively control the occurrence of grapevine diseases,improve the quality of leaves,and significantly increase the PSⅡ activity.It is conducive to promoting the growth and development of grapes in the current year and the germination of winter buds in the following year,which is the main way to cultivate robust grapevines.Simultaneously,red non-woven bags can more effectively improve the internal and external quality of grapes,which makes it possible to improve the quality and efficiency of healthy and safe grape production.