Study On The Water Consumption Characteristics And Regulated Deficit Irrigation Of Muskmelon

This experiment was carried out in the experiment station of center of agro-technical of Minqin country, Gansu from April 2009 to August 2009. We conducted full irrigation (CK), mild regulated deficit irrigation and moderate regulated deficit irrigation with melon varieties of Yindi and Yujinxiang in three growth stages including sowing to flowering time, flowering to fruit expanding stage and fruit expanding to picking time. In this experiment we researched The effect of different irrigation on water consumption, intensity of water requirement, modulus of water requirement, growing development, yield and quality of melon were researched to verify the pattern of water consumption and the response of melon on regulated deficit irrigation, determine the optimal irrigation regime and provide some theoretical reference for yield improving and water saving of melon. The main relults were as follows:(1) The water consumption of melon increased as the rise of irrigation. There was significant difference in water consumption of Yindi between deficit irrigation treatments and CK. To Yujinxiang there was also significant difference between deficit irrigation treatments and CK only except the mild water deficit in flowering to fruit expanding stage.(2)Different water deficit treatments had little influence on the pattern of water consumption in the whole period of melon but there was difference in water consumption. Under full irrigation the water consumption during the whole growth period of Yindi is 301.02 mm,32.99 mm higher than that of Yujinxiang. The water consumption of sowing to flowering time was small, flowering to fruit expanding stage was large and fruit expanding to picking time was small.(3)The water consumption intensity change of melon during whole growth period took on one-peak curve. The water consumption intensity was highest in flowering to fruit expanding stage, and the average water consumption intensity of deficit irrigation treatments of Yindi was 4.84 mm/d and that of Yujinxiang was 4.58 mm/d. The water consumption intensity was lowest in fruit expanding to picking time, and the averages in deficit irrigation treatments of Yindi was 1.92 mm/d and that of Yujinxiang was 1.24 mm/d.(4) After Yindi and Yujinxiang experienced moderate water deficit in sowing to flowering time and in flowering to fruit expanding stage, the vine length, stem thickness and leaf area were significantly lower than CK, which indicated that water deficit severely restricted the development of vine length, stem thickness and leaf area. Rewatering after mild water deficit, the compensatory effect was occurred in vine length and leaf area, which can decrease the differences to CK and made the differences not significant. (5) Irrigation had significant effect on the content of proline and soluble protein of melon leaves. The content of proline raised significantly and soluble protein decreased notably after experiencing mild and moderate water deficit in sowing to flowering time and flowering to fruit expanding stage. The content of proline were significantly higher than that of CK rewatering after moderate water deficit in flowering to fruit expanding stage.(6)After experiencing mild and moderate water deficit, melon photosynthetic rate was bimodal curve in three stages, transpiration rate and stomata conductance were bimodal curve in sowing to flowering time and in flowering to fruit expanding stage and were single peak curve in fruit expanding to picking time. The photosynthetic rate, transpiration rate and stomata conductance in both varieties decreased after mild and moderate water deficit in flowering to fruit expanding stage, while water use efficiency were improved. The photosynthetic rate in both varieties decreased after mild and moderate water deficit in fruit expanding to picking time but water use efficiency improved significantly.(7) The weight of simple fruit of Yindi in deficit irrigation treatments was significantly lower than CK. After moderate water deficit in sowing to flowering time and flowering to fruit expanding stage, the weight of simple fruit of Yujinxiang was significantly lower than that of CK and the effect of other treatments were not significantly.(8) After Yindi experienced moderate water deficit in sowing to flowering time and flowering to fruit expanding stage, the yield was significantly lower than CK. The yield of Yujinxiang in moderate water deficit treatment at flowering to fruit expanding stage was significantly lower than CK. The yield of Yindi (38740.68kg/hm2) experiencing moderate water deficit in fruit expanding to picking time wasn't the highest but yield water use efficiency (13.70 kg/m3)and irrigation water use efficiency (18.56 kg/m3) were the highest and the yield water use efficiency after mild water deficit in sowing to flowering was the second. Yujinxiang experiencing mild water deficit in sowing to flowering time had the highest yield water use efficiency (11.64kg/m3) and irrigation water use efficiency (16.06 kg/m3) was highest after moderate water deficit in flowering to fruit expanding stage. Based on comprehensive analysis of water use efficiency and yield of melon, we suggest that the soil water content should be controlled between 65% and 75% at sowing to flowering time,75% to 85% at flowering to fruit expanding stage and 55% to 65% at fruit expanding to picking time.