Effects Of Irrigation Threshold And Fertilization At Different Stages On Growth Of Drip-irrigation Muskmelon In Plastic Greehouse

China is a large agricultural country, which has great demand for water and fertilizer.However, it’s also one of the few countries with severe water shortage in the world. Now,china has became the biggest country which produce and consume fertilizer. What’s more,our country’s irrigation technique and fertilization technique are backward, compared with other countries, and the water use efficiency and fertilizer using efficiency are very low. As a result of that, not only water and fertilizer are wasted seriously, but also our environment and bodies will be hurt. It’s the key to solve the problem above that researching a efficient irrigation and fertilization technology for crop. And it will be of great significance to the sustainable development of our society.In plastic greenhouse, the effects of regulated deficit irrigation on growth, yield, quality and water use efficiency of muskmelon were investigated in spring and autumn. Five treatments were conducted according to relative soil moisture for vegetable and fruit two growth periods: T1(75%-75%), T2(75%-55%), T3(65%-65%), T4(55%-75%) and T5(55%-55%). The results were as follows: In the vegetative stage, plant height, stem diameter and leaf area were diminished as the degree of water deficit increased, and the date of most female flower opening was delayed. During fruit development, the fruit size and yield were lower with the increasing of water deficit. Finally, the yield of T1 was the highest, T5 was the lowest in both spring and autumn. And the yield of spring was more then two times than that of autumn.More water was irrigated in reproductive stage than vegetative stage, but the water use efficiency was lower. The WUE of T2 was the highest in both spring and autumn. Compared with T4, the spring irrigation of T2 decreased by12.7%, however, yield and water use efficiency increased by 5.3% and 20.5%,respectively. And the autumn decreased by 1.2%, while yield and water use efficiency increased by 26.2% and 27.7%, respectively.Regulated deficit irrigation had great effect on the quality of Muskmelon in autumn. Suitable water deficit could increase the contents of TSS, soluble protein, free amino acid, which the highest was T5, and Vc which the highest was T2, followed by T5. However, the titratable acid content was the highest in T1, the lowest in T5. There was significant difference between them. In the mass, the content of titratable acid decreased as the limit of irrigation lower.Taking all things into consideration, the T2(75%-55%) would be the most appropriate irrigation scheduling,which didn’t reduce the yield and quality much, but increased water use efficiency.Under the condition of fertigation in greenhouse, different treatments are designed according to fertilization in different growth period. In the whole growing periodof muskmelon, the irrigation low limit is 75% relative soil moisture and the proportion of fertilizer is N: P2O5: K2 O = 4: 2: 3. The results show that: in the vegetative period of muskmelon, increasing fertilization can promote the growth of plant. With the increase of fertilization, the plant height, numbers and area of leaves increase significantly. However, stem diameter decreas. In the reproductive period, the accumulation of dry matter and fruit development are mainly conducted. The change of stem diameter is not significant. With the increase of fertilization, the rate of fruit growth increases. Ultimately, the more fertilization the more yield. While, it’s not the more the better for fertilization. The yield will decrease when more than a certain limit, resulting in the lower fertilizer use efficiency. Meanwhile, fertilizing can promote crop water use,improving the water use efficiency of muskmelon. Think about quality, increasing fertilization is beneficial for the comprehensive quality in a certain range of fertilization.But, excessive fertilization will make the content of Vc, soluble protein, soluble solid reduce. All things considered, it’s the best cultivation patterns to make the yield, quality,water and fertilizer use efficient achieve the best balance, that the irrigation low limit is75% relative soil moisture and the total fertilization is N 300kg/ha, P2O5 150kg/ha, K2O225 kg/ha in greenhouse with dripped fertigation. We can use this pattern as a normal planting methods of muskmelon in Wuhan area.