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The objective of this study was to investigate health-promoting bioactive compounds and related enzymes of grape in response to regulated deficit irrigation under greenhouse and rain-shelter. The experiment had five treatments in 2016: FI (75%–90% of FC [field water holding capacity] from budburst to full maturation), DI (50%–60% of FC from budburst to full maturation), DI1(same as FI except 50%–60% of FC from budburst to anthesis), DI2(same as FI except 50%–60% of FC from anthesis to pea size) and DI3 (same as FI except 50%–60% of FC from pea size to full maturation). Another three treatments were setted in 2017: DI4(same as FI except 50%–60% of FC from pea size to véraison), DI5 (same as FI except 50%–60% of FC from véraison to mid ripening) and DI6 (same as FI except 50%–60% of FC from mid ripening to full maturation). Results showed that deficit irrigation post véraison was an efficient approach for inducing the bioactive compounds biosynthesis. Greenhouse cultivate could increase WUE, yield and improve the content of soluble sugar, Vc, soluble protein. While rain-shelter cultivate could accumulated higher bioactive compounds in grape tissue. Abbreviations: L-Phe, L-Phenylalanine; RES, Resveratrol; PAL, phenylalanine ammonialyase; C4H, cinnamate-4-hydroxylase; 4CL, 4-coumarate: coenzyme A ligase; PPO, polyphenol oxidase; L*, lightness; C*, chrome; SS, soluble sugar; TA, titratable acidity; Vc, vitamin C; SP, soluble protein; TSS, total soluble solids and MI, maturity index; ET, plant evapotranspiration; WUEET, water use efficiency based on plant evapotranspiration. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the changes of health-promoting bioactive compounds and related enzymes of 'Hutai No.8' grape (Vitis vinifera L.) in response to deficit irrigation. The experiment had five irrigation treatments: FI (75%–90% of FC [field water holding capacity] from budburst to full maturation), DI (same as FI except 50%–60% of FC from peasize to full maturation), DI1 (same as FI except 50%–60% of FC from peasize to véraison), DI2 (same as FI except 50%–60% of FC from véraison to mid-ripening) and DI3 (same as FI except 50%–60% of FC from mid-ripening to full maturation). Results showed that contents of different bioactive compounds and activity of related enzymes in grape leaves and berries tissue increased over control due to the application of deficit irrigation, and these changes were dependent on the fruit developmental period. Correlation analysis revealed the most significant positive relationship was observed between bioactive compounds and related enzymes activities in the grape seeds (r = 0.804). However, the most significant negative relationship was observed between bioactive compounds and polyphenol oxidase activity in the grape leaves (r = −0.769). Deficit irrigation treatment after véraison is an efficient approach for inducing the accumulation of bioactive compounds. [ABSTRACT FROM AUTHOR]

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]