Effects Of Different CO₂ Fertilizer Concentrations On Photosynthetic Characteristics,Yield And Quality Of Muskmelon In Greenhouse

Cucumis melo L.has a vast planting area in China.But in the Northern Greenhouse Cultivation for heat preservation causing CO₂ deficiency,while with the global modernization process causes the rise of atmospheric CO₂.In this experiment,Qingya Baiyu,a thin-skinned melon cultivar,was used as the research object.The effects of four different concentrations of CO₂(CK:400?±12?,T1:800?±24?,T2:1200?±36?,T3:1600?± 48??mol·mol^-1)on the growth and development of plants,photosynthesis,chlorophyll fluorescence parameters and fruit quality of thin-skinned melon were determined,To reveal the primary mechanism of CO₂ enrichment on Photosynthesis of muskmelon and determine the optimum CO₂ concentration for Muskmelon cultivation in Greenhouse in different periods in winter and spring in northern China,so as to provide theoretical basis for Precise Fertilization of muskmelon cultivation in winter and spring facilities.The results are as follows:1.Seedling stage: Compared with CK,T1 and T2 treatments increased photosynthetic rate by 52.9% and 72.9%.T2 treatment improved the photosynthetic rate most obviously,but compared with CO₂ enrichment multiple T1 treatment was the most economical and practical.Therefore,it is suggested that the concentration of fertilizer should be 800?mol·mol^-1 at seedling stage.2.Sprouting and budding stage: Compared with CK,T3 treatment has the most obvious effect.However,compared with CO₂ enrichment multiple,T1 is the most economical and practical photosynthetic index,and T3 is the most economical and practical growth index.Therefore,it is suggested that the concentration of fertilizer should be 1600?mol·mol^-1 during the budding stage of vine elongation.3.outcome periodNet photosynthetic rate: Compared with CK,T2 treatment increased by 40.9%,which was the most obvious and economical.Yield: Compared with CK,the yields of T1,T2 and T3 treatments increased by 19.51%,32.20% and 35.61%.T3 treatment has the most obvious improvement effect,but compared with CO₂ enrichment multiple T1 treatment,it is the most economical and practical.Quality: Compared with CK,T2 and T3 have greater influence.Compared with CO₂ enrichment multiple,T1 is the most economical and practical in terms of hardness,soluble solids,organic acids and sucrose,and T2 is the most economical and practical in terms of vitamin C,free amino acids and fructose.Therefore,it is suggested that the fertilizer concentration should be 800-1200?mol·mol^-1 in the fruiting period.4.The increase of photosynthesis in Melon under relatively low CO₂ concentration?T1?was due to the increase of chlorophyll content and the transport rate of triose phosphate.The increase of photosynthesis under high CO₂ concentration?T3?was mainly due to the actual quantum yield Y???,photosynthetic electron transfer rate and photochemical quenching of PS II..