Effect Of Load Capacity On The Growth And Development Of ’Daqing’ Grape Fruit And Analysis Of Differential Metabolites

’Daqing ’grape is a local variety in Ningxia.It is mainly planted in Wuzhong Litong District and Qingtongxia in Ningxia.The cultivated area is about 402000 m2,which has become a pillar industry for local rural revitalization.At present,the outstanding problems in the production of ’Daqing ’ grape are uneven yield and quality,thin skin,easy to break and difficult to keep fresh.In this study,12-year-old’Daqing ’grapes cultivated in field trellis were used as materials to study the effects of different loads 12 spikes/m2 trellis(CK),10 spikes/m2 trellis,8 spikes/m2 trellis on the appearance quality changes,intrinsic flavor and active substance accumulation,and fruit texture characteristics of ’ Daqing ’ grapes.The purpose of this study was to explore the relationship between the reasonable amount of spikes on the trellis of ’Daqing ’ grapes and the formation of fruit growth and quality,and to provide theoretical basis for the production of ’Daqing ’ grapes and provide reference for its postharvest preservation.At the same time,non-targeted metabolomics analysis during fruit growth was carried out to analyze the enrichment pathway of nutrients in ’ Daqing’ grape,aiming to elucidate the highly enriched nutrients during fruit development and explore the therapeutic value of ’Daqing’ grape.The results are as follows:(1)The effect of load on the appearance quality of ’ Daqing ’ grape fruit The results showed that compared with the control,the two low loads could promote fruit growth,increase fruit hardness and improve fruit color.When the fruit matured,the single grain weight,vertical and horizontal diameter of 8 spikes/m2 were the highest,followed by 10 spikes/m2.Fruit shape index and hardness 10 spikes/m2 maximum;fruit yellow and blue color value b*,color saturation C*and color index CIRG,10 spikes/m2 is the largest.(2)The effects of load on the intrinsic flavor and accumulation of active substances in ’Daqing ’grape berries were studied.The results showed that compared with CK and 10 spikes/m2,8 spikes/m2 was more conducive to the accumulation of soluble solids and total soluble sugar content and the decrease of titratable acid content.The ratio of solid to acid and the ratio of sugar to acid were 96.77 and 79.10,respectively.The changes of vitamin C,resveratrol and melatonin contents in ’Daqing ’grape berries were consistent under different loading levels,and the loading level had no significant effect on the content of active substances during fruit ripening.The content of vitamin C reached 19.9～24.45 mg/100g at fruit ripening stage.The content of resveratrol and melatonin in each organ of berry showed seed>peel>pulp.The content of resveratrol in pulp reached 0.23 μg/g～0.24 μg/g,and the content of melatonin reached 7.27 ng/g～8.35 ng/g,indicating that ’ Daqing ’ grape fruit was rich in various active substances during ripening.(3)The effect of load on the texture characteristics of ’ Daqing ’ grape mature fruit.The results showed that there was no significant difference in peel toughness and flesh hardness between the three load treatments,and the peel hardness was 10 spikes/m2.Compared with the control,the fruit firmness of 10 spikes/m2 and 8 spikes/m2 decreased.(4)According to correlation and the principal component analysis,the fruit quality of ’Daqing’grape were better under the load of 8 and 10 spikes/m2,the 10 spikes/m2 was best.(5)Based on metabolomics,the nutritional components and enrichment differences during the growth of ’Daqing’ grape fruits were analyzed.The results showed that 647 differential metabolites were identified in ’ Daqing ’ grape fruits.Among them,the KEGG pathway corresponding to the enrichment of metabolic differences was found to be more important for the color conversion and ripening of ’Daqing’ grapes.Betalain biosynthesis,Valine,leucine and isoleucine degradation,Flavone and flavonol biosynthesis,Biotin metabolism,Glycerophospholipid metabolism and Biosynthesis of unsaturated fatty acids biosynthesis.The most important metabolic pathways for fruit ripening were phospholipid metabolism and unsaturated fatty acid biosynthesis.Subsequent research on ’Daqing’grapes in different periods can start from these pathways.Based on above results,different loadings had a certain effect on the growth and accumulation of flavor active substances of ’Daqing’ grape fruit,but had no obvious effect on the fruit texture characteristics.The comprehensive evaluation suggested that the loading of 8-10 spikes per square meter of shelf surface should be selected At the same time,’wing’ grape fruit contains a variety of highly enriched nutrients with high nutritional value,and its active substances can be further excavated from the above metabolic pathways.