| With the development of the facility vegetables, long time continuous cultivation causedthe soil physical and chemical conditions deteriorated, the plant diseases and insect pestsfrequently occurred. This resulted in the yield declined and not only seriously hampered thesustainable development of facility agricultural production, but also had the adversely effecton the safety of agricultural products and ecological environment. In recent years, peppercultivation areas continued to expand because of the economic benefit. Pepper had becomeone of the important facility vegetables in northwest region and also proved to be the superiorcrop for increasing farmers′income and promoting rural economic development. Mulchingwere widely used in agricultural production because of its good effect, however, this studywas mainly on the field crops and also concentrated one of the mulching effect on crops. Andlacked of systematic research on the effect of various mulching practices, especially in thegreenhouse vegetable production this system was less researched. Therefore, this study wascarried out in the experimental greenhouse of Institute of the soil and water conservation, theChinese Academy of Science and Ministry of water Resources in Yangling in2011and2012.And the objective of the research was to study the effect of the different mulching practices(CK, without mulching; FM, plastic film mulching; CM, combined mulch with plastic filmand wheat straw; SM, straw mulching) on the physiological characteristics and soil conditionsof hot pepper in greenhouse. And multiple objective comprehensive evaluations wereconducted with principal component analysis method and grey relational analysis method.The following results were obtained:(1) Mulching improved the soil environment. Soil water content (SWC) was higher underthe mulching practices than under no-mulching condition and SWC followed the orderCM>FM>SM>CK; Soil temperature had significantly difference between different treatments,mulching had warmer effect and soil temperature was also higher under mulching than under no-mulching; Mulching increased the crop absorption of nitrogen, phosphorus and potassiumand increased the fertilizer use efficiency, which significantly improved soil environmentalquality. Soil respiration (Rs) of hot pepper was changed under mulching practices. Thehighest Rs was obtained under CM treatment and the Rs measured in the control soil wasalways lower than that for any mulch material treatment over the entire growing season; Thedifferences between CK and FM and CM and SM were significant at p<0.05; Based on thegrey correlative analysis, the result showed that soil organic matter, root vigor, soil and airtemperature were the key influencing factors under mulching practices and the relationship ofRs and soil organic matter was most closely, pH had the lowest correlation coefficients withRs which was0.707.(2) Physiological characteristics of hot pepper were changed under mulching practices.During the growth process of hot pepper, the leaf net photosynthesis rate was significantdifference between different treatments, being highest for CM application (15.98umol CO2m-2s-1), lowest for CK management (8.15umol CO-12m-2s); Results indicated that thephotosynthesis-light response curves of hot pepper was appropriate to a non-rectangularhyperbolic model, measured curve and simulated curve were consistent (Decision coefficientswere higher than0.9); Apparent quantum efficiency was higher under CM (0.103) and FM(0.08) than under CK (0.07) and SM (0.06); CM maintained more lower light compensationpoint (LCP) and SM maintained higher light saturation point (LSP), which indicated pepperwas more adapted to low light under CM treatment while pepper was more adapted to stronglight under SM practices.(3) Analysis of yield, water use efficiency and economic benefits of hot pepper undermulching practices. Yield was highest under CM treatment and FM, CM, SM increase yieldby55.76%,160.58%,135.58%, respectively; Economic income of pepper was highest underCM (16.26yuan m-2) while lowest under CK (6.24yuan m-2); Water use efficiency wassignificant difference between different treatments (p<0.05) and followed the orderCM>SM>FM>CK, which indicated CM was significantly better than other treatment in termsof water conservation, increasing yield and income.(4) Fruit quality of hot pepper was changed under mulching practices. Pepper fruit lengthfollowed the order CM>FM>SM>CK, and also showed significant difference between different treatments (p<0.05); Pepper fruit diameter under FM, CM and SM was wider by5.18%,12.35%and1.19%than CK management, while CM was the widest; Pepper fruitshape index under CM was changed smallest (0.03) during the growing season, which showedCM was better to maintain the consistency of the products; Vitamin C of pepper was highestfor FM (33.81mg kg-1) while the lowest under CK (22.73mg kg-1) treatment; The content ofpepper capsaicin was increased under CM and SM treatments and also showed significantdifference between CK and FM treatments; Mulching reduced the nitrate content in pepperfruits, FM had the lowest nitrate content (29.81mg kg-1).(5) Principal component analysis method and grey relational analysis method were usedto conduct the multiple objective comprehensive evaluations. The result of comprehensiveevaluation was CM>SM>FM>CK while using principal component analysis methods, CMgot the highest score (4.21) while CK got the lowest score (1.53); the result of comprehensiveevaluation was CM>SM>CK>FM while using grey relational analysis method, the correlationcoefficients was highest under CM (0.912) while lowest under FM (0.709) treatment; CM wasgot highest score and correlation coefficients under the two comprehensive evaluationmethods, indicating CM treatment could achieve pepper high-efficient, high-quality andsoil-quality production and CM should be promoted in facility and efficient agriculture. |
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