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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]

Soil respiration is an important component of the carbon cycle and is also recognized as one of the primary pathways that release CO2from the soil into the atmosphere in terrestrial ecosystems. Soil CO2flux resulting from soil microbial activity and root respiration is one of the major components of the total carbon flux in agro-ecosystems. However, the impact of agronomic practices such as mulching on soil respiration in greenhouses has been less thoroughly studied. Consequently, field experiments were conducted during the growing seasons of 2011 and 2012 in greenhouse to evaluate soil respiration and the biotic and abiotic factors that influence it in hot pepper cultivation under four types of mulch practices (without mulch, wheat straw mulch, plastic film mulch, and combined mulch with plastic film and wheat straw). Soil water content had an overriding influence on soil respiration in hot pepper culture during the growing season under mulching treatments in a greenhouse, whereas the influence of soil temperature was relatively less. Additionally, the study showed that root biomass and root vigor should also be incorporated as predictor variables for soil respiration under mulching in greenhouses. [ABSTRACT FROM AUTHOR]

Soil degradation resulting from recropping of greenhouse-cultivated cucumber (Cucumis statirus L.) has become a serious problem for production. The objective was to determine the soil degradation processes and make suggestions for prevention. Experiments were conducted in a solar greenhouse 4.0 m long and 0.7 m wide during 2001–2005 in northern China. In 2001, every fourth plot was filled with continuously cropped typical sandy soils from the winter–spring cucumber season for 0, 1, 4, or 8 years, respectively. Soil particle composition, nutrient content, and species of soil microbes were analyzed. A grafted cucumber with squash root was transplanted to the continuously cropped soil. Results indicated that cucumber fruit productivity increased with increases of recropping year up to the fourth year and then decreased thereafter with continuous cropping. Soil particle percentages did not change significantly as recropping years increased. Soil nutrients were not the main factor for decreased productivity. As the number of recropping years increased, the soil available nitrogen (N), available phosphorus (P), available potassium (K), and organic content increased. The soil bacteria and fungi increased after 3 or 5 years of recropping, and soil actinomycetes decreased significantly after 5 years of recropping. The ratio of bacteria–fungi–actinomycetes changed, populations of fungi and bacteria increased, and the ratio of actinomycetes decreased, which led to an increase in the occurrence of pathogenic and soil-borne microbes and a decrease in fruit productivity, which were assumed to be the main factors of soil degradation. To stop recropping from influencing populations of fungi, bacteria, and actinomycetes, recropping should not be utilized after 4 years of recropping in order to continue with vegetable productivity in greenhouses. [ABSTRACT FROM AUTHOR]