Study On Irrigation Schedule Of Jujube Under Drip Irrigation Based On Lower Soil-Moisture Limit

These days the farmer were often sightless concerning the problem, that when to start irrigation during the whole Jujube growth time. The mode that just pursue high yield in simplex aspect might lead water-wasting and water-using inefficient and influence fruit quality. So in order to discuss the matter of the right irrigation time for Jujube, the experiment need make clear that how the Jujube consume water, and evaluate the right lower limit of irrigation according to water saving、high yield、high efficiency and high quality. Be aimed at the actual chief conflict between the resource shortage of water and soil, and make full use of the limited water and soil, the experiment was arranged to ravel the right lower limit of irrigation and irrigation schedule for Jujube and discuss the principium of the effect of water-fertilizer coupling, and screen out the reasonable water-fertilizer coupling, and to play the water-fertilizer coupling effect adequately. In order to make clear the variation pattern of soil water-heat when the Jujube was covered with plastic film under drip irrigation, the experiment was arranged to study variation pattern of soil temperature in covering-film location or in no-film location on different weather condition and before or after irrigation in Jujube woodland.This paper studied Jujube tree which was7years through field experiment. The experiment was conducted at Aksu Agriculture Science Demonstration Garden-Plot in Xinjiang Province. The experiment designed5levels of lower limit of irrigation (including40%、50%、60%、70%、80%of field holding capacity of soil water) and studied the speciality of water consumption on5levels of lower limit of irrigation under drip irrigation, and analysed the affect that the lower limit of irrigation act to Jujube’s growth character、yield、quality and efficiency of using water, and then appraised the right lower limit of irrigation and irrigation schedule for Jujube by water saving、high yield、high efficiency and high quality. Based on the irrigation schedule, the experiment studied the effects of water-fertilizer coupling on Jujube under drip irrigation with plastic film. In addition, the experiment analyzed the variety pattern of soil temperature in Jujube woodland under drip irrigation condition.The results show that:(1) In the depth of20cm-60cm, when the lower limit of irrigation was higher than60%, the quantity of water-consuming would increase go with the lower limit of irrigation rose; but when the lower limit of irrigation was lower than60%, the quantity of water-consuming would not continue to increase with the lower limit of irrigation rose. The relationship between the lower limit of irrigation、Jujube yield and water-consuming could be described by a mathematical model.(2) The relationship between the lower limit of irrigation、Jujube yield and water-using efficiency could be described by a quadric parabola. In theory, when the lower limit of irrigation was56.7%, Jujube yield was the most, and when the lower limit of irrigation was54%, water-using efficiency was the highest. The affect the lower limit of irrigation acted to the content of Vitamin C and Total Acid in Jujube was notable. When the lower limit of irrigation was60.9%, the content of Vitamin C was the highest. When the lower limit of irrigation was56.7%, the content of Total Acid was the lowest. When the per of irrigation for Jujube was450m3/hm2, the right lower limit of irrigation was55.3%, the times of irrigation were17and the total irrigation amount was7650m3/hm2.(3) The mathematical model for Jujube yield and its main affecting factors water and fertilizer is established. Appropriate water and fertilizer supply could improve the effect of increasing Jujube yield. But when water and fertilizer supply was excessive, the Jujube yield would decrease. When Jujube yield reached the top, the best pattern was579.7m3/hm2of irrigation and1081.2kg/hm2of fertilizer, which included N254.29kg/hm2, P2O5190.64kg/hm2, K2O81.04kg/hm2.(4) When the soil depth was deeper, the changing extent of soil temperature was more slower、lager and smaller. Soil temperature in the covering-film location was higher than that in the no-film location on different weather condition. On cloudy and rainy day, when the soil depth was deeper, the influence of rainfall on soil temperature was lighter. The variety extent of soil temperature in no-film location was larger than that in covering-film location. No matter in covering-film or in no-film location, the soil temperature during irrigation stage was lower than that without irrigation. Before irrigation, the soil temperature in covering-film location was lower than that in no-film location in heating-up stage, but in heating-down stage, the opposite was the case. After irrigation, covering-film mode could cut off evaporation and reduce potential energy consumption effectively and play a good role in heat-preservation. The effect of increasing soil temperature in covering-film location was more obvious than that in no-film location. In addition, the soil emanate heat more quickly in no-film location than in covering-film location, which made the soil temperature in each depth was higher in covering-film location than that in no-film location after irrigation.