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To understand the response of grape (Hutai No.8) quality and soil respiration (Rs) to different soil relative water contents (SRWCs), this study was designed with three soil moisture levels (A: 80-95%, B: 60-75%, and C: 40-55% of SRWC) for grape cultivation. Meanwhile, environmental factors, including air temperature (Ta), air relative humidity, and light intensity, were also recorded. The results showed the following: (1) Through the comprehensive analysis of fruit quality by the method of subordinate function, we concluded that the optimum soil moisture treatment was 60-75% SRWC, and the soluble sugars, proanthocyanidin, and resveratrol were most abundant. In addition, vitamin C (Vc) content was the largest under C treatment. (2) Photosynthetic characteristic under high soil moisture was better than those under low soil moisture condition during grape coloring periods, and it was largest under A treatment in 2015. Rs rate was in accordance with the trend of grape photosynthesis. High soil moisture could accelerate the photosynthetic rate of grape leaves and increase Rs. (3) Correlation analysis showed that higher soil moisture and air humidity and lower soil temperature (Ts) and Ta could promote the accumulation of more nutrients in grape berries; it also could increase photosynthetic rate and Rs during grape coloring periods. In conclusion, 60-75% SRWC was the optimum soil moisture condition, which could improve the nutrient contents and accumulate more bioactive substances. Of course, keeping a lower Ts and Ta, as well as higher air humidity, was also necessary. Abbreviations: SRWC: soil relative water content; A, 90-95% SRWC; B, 70-75% SRWC; C, 40-55% SRWC; Rs: soil respiration; Ta: air temperature; Ts: soil temperature; OPC: proanthocyanidin; TSS: total soluble solids. [ABSTRACT FROM AUTHOR]

BACKGROUND Spraying selenium (Se) fertilizer is an effective method for Se-enriched fruit production. Sugar content in fruit is the major factor determining berry quality. However, changes in sugar metabolism in response to Se fertilizer are unclear. Hence, this study was conducted to identify the effects of Se fertilizer on sugar metabolism and related enzyme activities of grape berries. Additionally, production of leaves with and without Se fertilizer was also investigated. RESULTS Acid invertase ( AI) activity, total soluble sugar and Se content in berries, and photosynthetic rate in leaves produced under Se fertilizer treatments were higher than that of control. Glucose and fructose were the primary sugars in berries, with a trace of sucrose. In both berries and leaves, neutral invertase activity was lower than AI, there was no significant difference in neutral invertase, sucrose synthase and sucrose phosphate synthase between Se fertilizer-treated and control. In berries, AI showed a significant positive correlation with glucose and fructose; also Se content was significantly correlated with sugar content. CONCLUSION AI played an important role in the process of sugar accumulation in berries; high AI activity in berries and photosynthetic rate in leaves could explain the mechanism by which Se fertilizer affected sugar accumulation in berries. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Table grape is a fruit well suited for consumption as fresh-cut product. Selenium (Se) is an essential mineral nutrient for human growth, and Se-deficiency is a worldwide nutrition problem. Meanwhile, with Se-enriched fruits is becoming more and more popularity, improving Se content and fruit quality in grape is especially important for human health. Se content of grape berries was increased by Se fertilizer application, the maximum Se content and raise ratio of European and American species was 34.96 ug kg −1 FW and 36.88% respectively, higher than those of Eurasian species 19.46 ug kg −1 FW and 21.40%. In addition, Se fertilizer increased nutrition quality, including soluble sugar, Vc, soluble protein, soluble solid, reduced organic acid, while it had no effect on polyphenol antioxidants of Eurasian species. K and Ca content of grape berries was significantly increased, and reduced accumulation of heavy metals Pb, Cr, Cd, As, Ni. Se in fruits was positively related to fruit quality, and negatively correlation of heavy metals. In conclusion, Se fertilizer can be used to increase Se content of grape, especially for European and American species, with significant effect of increasing grape nutrition quality and an effective means of lowering heavy metals. [ABSTRACT FROM AUTHOR]

Selenium (Se) deficiency in humans could be improved by biofortification of food with selenium, 1-Methylcyclopropene (1-MCP) treatment is beneficial for the non-sulfur storage of fresh fruit. This study investigated fruit quality of table grape (Hutai No.8) with foliar Se fertilizer at maturity, and fruit quality changes of table grape during shelf life stages that caused by postharvest 1-MCP treatment in 2016 and 2017. The results showed that foliar Se fertilizer application significantly increased Se content in grape berries at maturity, and the raised rate were 43.09% and 33.24% compared to that of control in 2016 and 2017 respectively, meanwhile it increased the nutritional components in grape berries, including soluble proteins, soluble sugars, Vitamin C, total soluble solids, proanthocyanidin content and so on, and decreased the titratable acidity content. During shelf life stages, 1-MCP application decreased the decay number of grapes, and SE + 1-MCP treatment had the most excellent fruit quality among all treatments in two consecutive vintages. In conclusion, Se fertilizer application could increase Se content in grape berries, also improved the fruit nutritional and health care values at maturity. 1-MCP application could delay the process of ripening and senescence for Se-enriched grape and maintaining the postharvest quality of table grape during shelf life stages, it allows us to market the fruit at a more advanced ripening stage without quality loss. [ABSTRACT FROM AUTHOR]