Study On The Photosynthetic Characteristics, Yelid And Quality Formation Of Muskmelon

Muskmelon is popular because of its high nutritional value and delicious taste. However the influence factors during the period of growth and development such as climate, light, water management and unreasonable management always resulted in a loss of yield and quality. The experiment with three varieties of muskmelon 'Changxiangyu', 'Jiqing','Qiuyue'as materials, studied on the photosynthesis characteristic, dynamic regularity of vegetative growth and reproductive growth, dry matter accumulation and distribution under different amount of water and fertilizer treatments. Meanwhile, explored the influence of the fruit-setting nodes, the fruit-setting leaf age and leaf area on the weight of single fruit and content of total soluble solids. The main results as followed:(1) Varieties, cultivation season, growth period, fruit node had influences on photosynthesis characteristic. The net photosynthetic rate of whole plant was on the decline during the period of fruit-bearing. In late period of fruit-bearing, the net photosynthetic rate of'Jiqing'was higher than other varieties. Meanwhile,there was no signiflcant difference about the net photosynthetic rate among different fruit-setting positiots of 'Changxiangyu'and 'Jiqing',and the net photosynthetic rate of'Qiuyue'with middle fruit-setting node was higher than the one which set fruit in low and high node.(2) In terms of all the varieties, the speed of plant growth in autumn was faster than spring. The growth dynamic of leaves on different nodes all rendered as "S" curve, and the piecewise function established on the basis of "S" curve was more intuitive to reflect its growth dynamic.(3) On the basis of traditional regression coefficient method, the optimizing mathematical model S=-13.2897+(L-W)0.943+0.267N1·L+0.153 N2·L,which consists of the notch variable N1·L and N2·L had a better prediction. Model fitting results showed that the coefficient of determination R2 and the root mean square error RMSE were 0.9886 and 7.686, respectively. The results of external validation of the model reflected that the correlation coefficient r and the root mean square error RMSE were 0.9950 and 7.201, respectively.(4) Increased irrigation amount of water and fertilizer in the appropriate range could improve the net photosynthetic rate, promote plant growth and fruit development as well as the amount of dry matter accumulation and increase the weight of single fruit and quality. It was recommended to increase irrigation amount of water and fertilizer for promoting dry matter accumulation of 'Changxiangyu'(big melon shape) while the irrigation amount of water and fertilizer should not be too much for'Jiqing' and 'Qiuyue' with small melon shape planted in a plastic greenhouse with drip irrigation system.(5) The fruit-setting nodes, the fruit-setting leaf age and leaf area all had influences on the weight of single fruit and quanlity.In terms of yeild, it was more reasonable to set fruit according to leaf age and leaf area.In terms of quality, it was more reasonable to set fruit according to leaf age and leaf area. According to the comprehensive consideration for the influence of the fruit-setting nodes, the fruit-setting leaf age and leaf area on yield and quality under the condition of robust irrigation amounts of water and fertilizer, the most suitable fruit-setting node was 13-14th node while the leaf age was 21(Leaf area was 3722cm2) for'Changxiangyu',and the most suitable fruit-setting node was 10?11th node while the leaf age was 19-20 (Leaf area was 2955?3347cm2) for'Jiqing',and the most suitable fruit-setting node was 13-14th node while the leaf age was 22 (Leaf area was 4702cm2) for'Qiuyue'.