The Growth Effect Of Muskmelon Under Aerated Irrigation In Greenhouse

Aerated irrigation is a new technology of mulched subsurface drip irrigation. It can directly improve the gas content in the root zone, prevent root zone from hypoxia stress, and promote its economic production. The research of aerated irrigation concentrated mostly in horticulture in China. Therefore, the effect of ventilation volume combined with irrigation amount on growth, output and quality of muskmelon is future studied under mulched subsurface drip irrigation in the greenhouse. The experiment studied the growth, physiological mechanism, production, quality and laws of water consumption of muskmelon in the condition of aerated irrigation under two patterns—one dealing with water combined with gas and the other water separated from gas. It can be concluded as follows:(1) Water yields of emitters varied in the different positions of drip irrigation system which was functioned by the Venturi aerated tube. In the same conduction, outgassing volume was also different, discharge through emitter in the condition of non-aeration had the same law as that under aeration. As the pressure difference increased, the . difference of discharges between aeration and non-aeration and outgassing through emitters showed double peaks. The ratio of vapor content of each emitter was compared in various emitters and various pressure difference. Then it could be concluded that the ration of vapor content increased as pressure difference, the difference of each emitter simultaneously expanded and variation ranges also increased.(2) Aeration was a factor of promoting the upward growth, but not an important factor. Moderate aeration could promote the growth of stems, but irrigation had negative effects on the growth of stems, which couldn't be changed in spite of aeration in the root zone. Aerated irrigation promoted leaf expansion on the Seedling stage and flowering and fruit bearing periods. 0.75Ep irrigation with 1.0 and 0.5 times aeration(take 50% soil effectie drainage as the base) formed appropriate biomass, had a more reasonable distribution of root and shoot, and provided the conditions for high crop yield.(3)The effect of aeration on the relative content of chlorophyll is lower than that of irrigation on the Seedling stage and flowering and fruit bearing periods. The leaf photosynthetic rate, stomatal conductance and transpiration rate all presented bimodal curves under aerated irrigation. The photosynthetic rate, stomatal conductance and transpiration rate of two treatments under 0.75Ep irrigation with 1 times ventilation volume and 1.0Ep irrigation with 0.5 times ventilation volume were higher than other treatments. The photosynthetic indicators and photosynthetically active radiation had a good cubic linear relationship. And the fitting degree of transpiration was relatively higher than other photosynthetic indicators.(4) Aerated irrigation had a great influence on the output and quality of the single plant. The yields increased obviously under 1.0Ep irrigation with 0.5 times aeration and 0.75Ep irrigation with 1.0 times aeration. Water use efficiency (WUE) of 0.75Ep irrigation was higher than 1.0Ep's, and had the same law as the yield. Aeration had a significant influence on the soluble sugar content in the condition of moderate water stress. Soluble albumen and organic acid content under 1.0Ep irrigation were higher than 0.75Ep's, Vitamins C of 0.75Ep irrigation was obviously higher than 1.0Ep's.(5) The effect of two patterns—water combined with gas and water separated from gas—was compared on the growth indicators, output and laws of water consumption of muskmelon. Then the conclusion was obtained that the output and WUE of single plant under water separated from gas were superior to those under water combined with gas. The principal component analysis of yield, WUE and irrigation amount were conducted, the result of which was that the weight of each factor was 0.5127, 0.7604 and -0.3987.And TOPSIS was used to determine the optimum irrigation method, which concluded that the treatment T2 was best,T7 second best and T10 worst, in other words, the mode of water separated from gas was better than that of water combined with gas. The aerated system of water separated from gas was not perfect. Therefore, it is proposed that the modes of water combined with gas under 0.75Ep irrigation are put to use,thereby reaching the aim of high production ,water conservation and efficiency.