| An increasing population and an expected higher standard of living in China have contributed to the rapid development of muskmelon production, particularly in solar greenhouse systems. Water and nitrogen play important role in the process of muskmelon growth. At present, phenomenon of blind fertilization and irrigation caused the frequent disease of crops, reducing yield, quality losses and waste of water and fertilizer resources in greenhouse production. It is very importance for theory and technology of water and nitrogen research and scientific irrigation fertilization management measures to improve the water and nitrogen use efficiency, reasonable utilization of water and fertilization resources, agricultural vegetable yield, quality and defend of ecological environment.The test crop was yi pin tian xia 208, a local variety of muskmelon, three experiments were carried out:cultivation ⅠandⅡ in spring, cultivation in autumn. According to the daily meteorological data observed by the mini-meteorological station located inside the solar greenhouse, irrigation application amount was determined by using FAO Penman-Montieth equation. cultivation Ⅰ in spring, muskmelon plants were subjected to three irrigation treatments, 60%, 80% and 100% of crop ETc(W1,W2 and W3) and three N levels, N1(60 kg N/hm2), N2(95 kg N/hm2), N3(130 kg N/hm2), there are 9 treatments. Cultivation in autumn, there are 9 treatments, muskmelon plants were subjected to three irrigation treatments, 70%(W1), 100%(W2) and 130%(W3) of crop ETc(Evapotranspiration) and three N levels, N1(70 kg N/hm2), N2(130 kg N/hm2), N3(180 kg N/hm2). Cultivation Ⅱ in spring, muskmelon plants were subjected to three N levels, N1(60 kg N/hm2), N2(95 kg N/hm2), N3(130 kg N/hm2) and three fertigation frequency treatments, F1(5 d)、F2(10 d)、F3(15 d). It is study on effects water, nitrogen and fertigation fruquency on greenhouse muskmelon growth, yield and quality and so on, which can provide to theoretical basis for high water-fertilizer use efficiency and the optimal regulation and control of greenhouse muskmelon1、Effects of water and nitrogen coupling on nitrogen uptake of muskmelon and nitrate accumulation in soil have shown that the above dry matter accumulation and amounts of N accumulation are obtained in the treatment of W2N2 and the content of soil NO-3-N is the highest in 0-15 cm soil layer after the muskmelon harvest and the content of soil NO-3-N decreases with the increase of soil depth. The accumulation of 0-60 cm soil NO-3-N increases with the increase of nitrogen rate and decreases with the increase of irrigation amount. The yield of muskmelon increases with the increase of irrigation amount and nitrogen rate except for the treatment of W3 and N3. 2 、 Effects of water and nitrogen coupling on growth and quality of greenhouse muskmelon under fertigation have indicated that net photosynthetic rate and vitamin C content of muskmelon showed a trend of decrease after the first increase with the rise of irrigation water amount for the same nitrogen level. Total soluble solid of muskmelon descended with the rise of irrigation water amount for the same nitrogen level. Net photosynthetic rate, total soluble solid and vitamin C content of muskmelon showed that a trend of decrease after the first increase with the rise of nitrogen application rate for the same irrigation level. 3、Effects of water and nitrogen coupling on root growth and yield of greenhouse muskmelon, indicating that most of total root lengths were concentrated in the 0~30 cm soil layer, total root length increased slowly when soil layer increased. Total root length, a fruit weight and water use efficiency of muskmelon descended with the rise of irrigation water amount for the same nitrogen level. The highest values of total root length and a fruit weight were observed in W2N2, these values were 6625.48 cm and 818.94 g. Total root length and a fruit weight of muskmelon showed a trend of decrease after the first increase with the rise of irrigation water amount for the same nitrogen level. Water use efficiency descended with the rise of irrigation application rate, PFPN descended with the rise of nitrogen application rate. There is a significantly linear relationship between root length with less than 2 mm, root surface area, root dry weight and yield. Unreasonable irrigation and nitrogen applications could reduce a fruit weight, characteristic parameters of root of muskmelon, water use efficiency and partial factor productivity from applied N. 4、Effecs of water and nitrogen coupling on nutrient uptake, distribution and yield of greenhouse muskmelon, the results showed that the dry matter weight of various organs were increased with increase of irrigation and nitrogen application, and photosynthetic products transportation from vegetative organs to reproductive organs was improved. In the mature period, the amount of nitrogen, phosphorus and potassium in the muskmelon residue was about 4.06, 1.39, 4.65 g/plant under W3N3 treatment. The yield of muskmelon increases with the increase of irrigation amount and nitrogen rate. The highest muskmelon yields were obtained at W3N3 treatment with an average of 25.74 t/hm2. It is concluded that the irrigation level W3 and nitrogen level N3 could be recommended as the best combination of water and nitrogen which can improve muskmelon yield in the production of muskmelon under drip irrigation with plastic film mulch in experimental area. Potassium uptake of muskmelon during the whole growth stage was the highest, followed by nitrogen, and phosphorus was the least, Which indicates muskmelon is a K-favoring crop. 5、Effects of water and nitrogen coupling on the diurnal variation of photosynthesis and physiological characteristics of greenhouse muskmelon, indicating that the diurnal variation curves of Ta, RH, PAR had a single-peak and the Pn, Tr and Gs of muskmelon leaces under different water and nitrogen conditions had a single-peak too. The relationship between photosynthetic rate and yield of muskmelon showed a linear. Leaf photosynthetic rate of muskmelon is strongly dependent on water and nutrient supply. Under the condition of sufficient water, the photosynthetic rate was increased when nitrogen fertilizer was applied, and yields of muskmelon were increased with the increment of water and nitrogen fertilizer. Under the different water and nitrogen treatments, leaves malonaldehyde and proline of muskmelon change rule is same, the minimum and maximum value were obtained at W3N3 and W1N1, respectively. 6、Effects of nitrogen rate and fertigation frequency on growth and nutrient uptake of greenhouse have shown that nitrogen rate and fertigation frequency significantly influenced growth, dry mass and yield of greenhouse muskmelon. Under N2(125 kg N/hm2) and N1(85 kg N/hm2) rates, fertigation frequency with 5 d promoted muskmelon growth and induced a significant increase in N accumulation and dry mass of muskmelon, but there were not statistically different between F5 and F15 fertigation frequency treatments for muskmelon yield. Uner the F5 treatment, muskmelon production has not been signigicantly increased, and poor quality. It is recommended that increasing fertigation frequency could enhance yield and quality of greenhouse muskmelon in critical period of water and nutrition supply. |
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