Search

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]