Effect Of Water On The Growth, Characteristics Of Light Response And Fruit Quality Of Greenhouse Muskmelon

With muskmelon"Yipintianxia 208"plants as the experimental material, the trial adopted potted method and three experiments were carried out: cultivation in spring, cultivationâ… andâ…¡in autumn. From cotyledon flattening, four water treatments of cultivation in spring experiment were designed as supplementary irrigation of 40%, 60%, 80% and 100% of evapotranspiration during whole growth period. Four water treatments of cultivationâ… andâ…¡in autumn experiments were designed as supplementary irrigation of 60%, 80%, 100% and 120% of evapotranspiration from vine elongation to fruit harvesting, from fruit expanding stage to fruit harvesting, respectively. In order to provide basis for theoretical water management of muskmelon culture, the experiments studied the change of plant height, stem diameter, leaf area, chlorophyll fluorescence parameters, yield and fruit quality of muskmelon under different water treatments, discussed the effect of water on characteristics of light response of muskmelon leaves and the effect of irrigation amount on growth, yield and fruit quality during different growth stages. The main results were as follows:1. For cultivation in spring, plant height, stem diameter, leaf area and single fruit weight of muskmelon were highest, net photosynthetic rate, transpiration rate, intercelluar CO₂ concentration, light-saturated photosynthetic rate and apparent quantum efficiency were higher, while stomatal limitation value and water use efficiency were lower under the condition of supplementary irrigation of 100% of evapotranspiration during the whole growth period. Photosynthetic charateristics of leaf declined during 306.70℃·d^-1782.15℃·d^-1 effective accumulated temperature. With the increase of supplementary irrigation, chlorophyll content and minimal fluorescence (Fo) reduced, maximal photochemical efficiency of PSâ…¡(Fv/Fm) the excitation capture efficiency of PSâ…¡(Fv′/Fm′) increased, vitamin C, total soluble sugar, soluble solids and soluble protein content in muskmelon all rised first and then decreased.2. For cultivationâ… in autumn, from vine elongation to fruit harvesting, plant height, stem diameter, leaf area, single fruit weight and flesh thickness of muskmelon were highest under the condition of supplementary irrigation of 120% of evapotranspiration. Net photosynthetic rate, transpiration rate, intercelluar CO₂ concentration, light-saturated photosynthetic rate and apparent quantum efficiency were higher, stomatal limitation value and water use efficiency were lower under the condition of supplementary irrigation of 100% of evapotranspiration. When supplementary irrigation was further increased, photosynthetic charateristics declined. With the plant growing, effective accumulated temperature increased, photosynthetic charateristics of leaf declined. With the increase of supplementary irrigation, vitamin C, total soluble sugar, soluble solids and soluble protein content in muskmelon decreased.3. For cultivationâ…¡in autumn, from fruit expanding stage to fruit harvesting, single fruit weight was most heavy, net photosynthetic rate, transpiration rate and light-saturated photosynthetic rate of leaf were highest under the condition of supplementary irrigation of 120% of evapotranspiration. Apparent quantum efficiency and intercelluar CO₂ concentration were highest, stomatal limitation value and water use efficiency were lowest under the condition of supplementary irrigation of 100% of evapotranspiration. With the increase of supplementary irrigation, vitamin C in muskmelon fruit rised first and then decreased, total soluble sugar, soluble solids and soluble protein content in fruit decreased.So with the increase of supplementary irrigation, plant height, stem diameter and leaf area increased. They were highest under the condition of supplementary irrigation of 100% of evapotranspiration during the whole growth, and under the condition of supplementary irrigation of 120% of evapotranspiration from vine elongation to fruit harvesting, plants in autumn were higher than those in spring, while stem diatmeter was thinner. When supplementary irrigation were increased, chlorophyll content and Fo reduced,Fv/Fm and Fv′/Fm′increased, photosynthetic efficiency of muskmelon leaves went up, net photosynthetic rate, transpiration rate, intercelluar CO₂ concentration, light-saturated photosynthetic rate and apparent quantum efficiency increased generally, they were higher under the condition of supplementary irrigation of 100%, 100% and 120% of evapotranspiration during the whole growth, from vine elongation to fruit harvesting, from fruit expanding stage to fruit harvesting respectively, While stomatal limitation value and water use efficiency decreased and they were lowest under the condition of supplementary irrigation of 100% of evapotranspiration. The increase of supplementary irrigation was helpful to delay the decrease of photosynthetic capacity; stomatal limiting factor was the main factor of influencing photosynthesis of muskmelon leaves. When supplementary irrigation were increased, single fruit weight increased, it was highest under the condition of supplementary irrigation of 100%, 100% and 120% of evapotranspiration during the whole growth, from vine elongation to fruit harvesting, from fruit expanding stage to fruit harvesting respectively. From vine elongation to fruit harvesting, the earlier the water treatment, single fruit weight reduced. When supplementary irrigation were reduced, vitamin C, total soluble sugar, soluble solids and soluble protein content in muskmelon increased in different extent, quality were improved.Comprehensive consideration of morphological indexes, photosynthetic charateristics, yield and fruit quality of muskmelon, supplementary irrigation of 100% of evapotranspiration was suitable for muskmelon during vine elongation, supplementary irrigation of 120% of evapotranspiration was suitable for muskmelon during fruit expanding stage.