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]

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]

The conversion of farmland to forestland not only changes the ecological environment but also enriches the soil with organic matter and affects the global carbon cycle. This paper reviews the influence of land use changes on the soil organic carbon sink to determine whether the Chinese “Grain-for-Green” (conversion of farmland to forestland) project increased the rate of SOC content during its implementation between 1999 and 2010 in the hilly and gully areas of the Loess Plateau in north-central China. The carbon sink was quantified, and the effects of the main species were assessed. The carbon sink increased from 2.26×106 kg in 1999 to 8.32×106 kg in 2010 with the sustainable growth of the converted areas. The black locust (Robinia pseudoacacia L.) and alfalfa (Medicago sativa L.) soil increased SOC content in the top soil (0–100 cm) in the initial 7-yr period, while the sequestration occurred later (>7 yr) in the 100–120 cm layer after the “Grain-for-Green” project was implemented. The carbon sink function measured for the afforested land provides evidence that the Grain-for-Green project has successfully excavated the carbon sink potential of the Shaanxi province and served as an important milestone for establishing an effective organic carbon management program. [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]

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]

Water availability is a major factor that limits grain yield in the Loess Plateau of China. As competition for water intensifies between the agricultural and industrial sectors, it is essential to improve the agricultural water use efficiency (WUE) in the region. This requires the development of alternative irrigation schedules that maximize WUE. A field experiment was conducted for winter wheat (Triticum aestivum L.) during the period 1995–1998 to calibrate and test a biophysically based model WAVES in terms of grain yield and WUE predictions. Different irrigation treatments were carried out and the data collected included water and energy balance components, biomass, and grain yield. The model was run for 3 years with the measured meteorological data and grain yield was modeled using two different formulations. Comparisons between the measurements and the model predictions were made with 3 years of independently measured data. The results showed that the simulated grain yield and WUE based on biomass and harvest index are in better agreement with the measurements than those based on transpiration and harvest index. The model is sensitive to different irrigation treatments, and in reasonable agreement with field measured data. Results from both the field experiments and model simulation showed that evapotranspiration was greatest in the highest irrigation treatment, but the grain yield was not the highest and WUE was relatively low. Appropriately limited irrigation could improve the grain yield and WUE. Therefore, the WAVES model can be used to simulate grain yield and WUE of winter wheat in the Loess Plateau. A better irrigation scheme should aim for maximum WUE and any attempts to solely increase grain yield in the region would not be sustainable. [Copyright &y& Elsevier]

On the Loess Plateau of China crop yields are mainly limited by available water. A field experiment was conducted for winter wheat (Triticum aestivum L.) during the period 1995–1998 to evaluate the effects of limited irrigation on yield and water use efficiency. A controlled soil water deficit, either mild or severe, was applied at different stages of crop growth. Photosynthesis rate, soil water content, and root and shoot dry mass accumulation were measured. Final grain yields and total water consumption were recorded, and the water use efficiency and harvest index were calculated.The results showed that, in different growing periods, evapotranspiration, grain yield, biomass, water use efficiency (WUE), and harvest index depended on the controlled ranges of soil water content. Grain yield response to irrigation varied considerably due to differences in soil moisture contents and irrigation scheduling between seasons. Evapotranspiration was largest in the high soil moisture treatment, and so was the biomass, but this treatment did not produce the highest grain yield and WUE was relatively low. WUE increased linearly with harvest index (HI) and improvement in the latter gave better WUE under limited irrigation conditions. Appropriately controlled soil water contents can improve the grain yield, WUE, and harvest index. Consistently high values of grain yield, WUE, and harvest index were produced under conditions of mild water deficit at the seedling and start of regrowth to stem-elongation stages, in addition to a further soil water depletion at the physiological maturity to harvest stage. We therefore suggest that periods of mild soil water depletion in the early vegetative growth period together with severe soil water depletion in the maturity stage of winter wheat is an optimum for limited irrigation regime in this region. [Copyright &y& Elsevier]