Influence Of Water And Fertilizer Coupling On Physiological Characters And Yield Quality Of Pumpkin On Loess Plateau

Along with the improving of requirement of people on the nutritional diet and the understanding of nutritional quality and function properties of pumpkin, the pumpkin product growing important. Improving the quality and yield of pumpkin has become the urgent problems which need to be solved.Unreasonable irrigation and fertilization is the resion of pumpkin quality decline, the waste of production cost and environment pollution risk arising, reasonable irrigation and fertilization make assurance to achieve high yield and quality of pumpkin. This experiment chose the Loess Plateau Hilly Region, useed the optimize design of the three ingredients N, P, K, to research the impact of three fertilizer factors on the pumpkin quality. And study the interaction effects on the three levels of water( H , M, L, soil moisture content of 80% -90%, 60% -70%, 40% -50%) and 9 fertility levels(N0P0, N0P1, N0P2, N1P0, N1P1, N1P2, N2P0, N2P1, N2P2, fertilization for N0, P0=0 kg/hm2, N1 = 50kg/hm2, N2 = 95kg/hm2, P1 = 35kg/hm2, P2 = 70kg/hm2)coupling on the physiological characteristics ang yield quality of pumpkin, to provide scientific water and fertilizer level of high yield and quality of pumpkin. The results show that:1.Under the influence of fertilization, use the N,P and K three factors optimize design, and through the quadratic polynomial regression model analysis, draw that: Nitrogen and Phosphate fertilizer has obvious interaction on the quality of pumpkin, Nitrogen and Potash fertilizer has obvious interaction on the dry matter content of pumpkin. The reasonable ratio for optimal pumpkin quality is N:P:K=1:0.83:0.28.2. Under the influence of the coupling of water and fertilizer, the changes of pumpkin photosynthetic characteristics are all have peak at noon 13:00. The net photosynthetic rate and stomatal conductance showed from low to high to reduce trend, and the transpiration rate showed from medium to high to medium to reduce trend. Appropriate water supply is benefit to leaf chlorophyll content and photosynthetic characteristics, excessive moisture is inhibited. The optimal fertilization and irrigation to improve the leaves protect enzyme is: the soil moisture content 60%-70%, the fertilization amount in N 40-50 kg.hm-2, P 30-35 kg.hm-2.3. The impact of soil moisture to pumpkin Vc content reached the significant level, the soil moisture too high is not benefit to the fruit Vc accumulation. Both of soil musture and fertility impact notable to nitrate content , and both of them are impact not significant to pumpkin fruit EC. Fertility is an important factor to control the souble sugar content and soluble protein content. Appropriate water and fertilizer supply could increased the yield of pumpkin, when the water supply is appropriate(the soil moisture is 40%-50%), the amount of nitrogen fertilizer should be controlled to avoid the interaction of nitrogen and phosphorus. In the water stress(the soil moisture is 60%-70%), with the fertilization increased the yield decreased.4. The soil respiration intensity was highest in the fruit enlargement period, and it decreased obviously in the pumpkin ripe harvest period. And the middle level of the water and fertilizer treatment (the soil moisture is 60%-70%, N1P1) helps improve the soil respiration intensity. Determinating the soil nutrients after the pumpkin harvest, the organic matter content and alkali-soluble nitrogen content was higher than before planting. The available phosphorus content and available potassium content were declined than before planting, and the middle level of the water and fertilizer treatment (the soil moisture is 60%-70%, N1P1) helps synthesis the available phosphorus and organic matter, water and fertility too high or too low will decrease the soil organic matter cintent. High water (the soil moisture is 60%-70%) was benefit to synthesis alkali-soluble nitrogen. With the fertilization increased, the alkali-soluble nitrogen increased show upward trend. And high water will inhibit synthesis the available potassium.5. With the soil moisture content is 60%-70% and fertilization is N: 50-75kg.hm-2, P: 30-40 kg.hm-2, it was benefit to high yield and high quality of pumpkin and the land sustainable.