Study On The Jujube Irrigation System And The Key Technology Of Irrigation Decision In Arid Area

In recent years,the contradiction between the demand for and supply of water for jujube cultivation in southern Xinjiang has become increasingly prominent.Old and extensive irrigation methods and backward irrigation technology cannot solve practical problems.Therefore,in this paper,the irrigation system and canopy meteorological changes in the 10-year-old ash jujube tree in the Korla region were studied using the field drip irrigation technology.Three groups were set up for the trial,and the irrigation quotas were C1(360 mm),C2(540 mm),and C3(720 mm),and each group had two replicates.The effects of different irrigation quotas on the physiological indicators and yield of jujube trees were studied to determine the suitable minimum and maximum irrigation levels of jujube and soil moisture monitoring points.At the same time,according to the observation data of the automatic weather station,a soil moisture prediction model based on the jujube tree canopy temperature and atmospheric temperature difference(?T)was established and the ?T threshold was proposed to determine the most accurate irrigation time for red dates reaching the lower irrigation threshold.It will provide reference for the establishment of date irrigation system and improvement of irrigation decision-making technology.The following conclusions were obtained through research:(1)Different irrigation quotas have significant effects on physiological indicators and water consumption of jujube trees.After increasing the irrigation quota,the water consumption,physiological indexes and jujube volume of jujube trees increased significantly;when the irrigation quota was reduced,the physiological development of the plants was slightly inhibited,and the premature aging of leaves appeared,which was not conducive to the normal development of fruit trees.Therefore,under the premise of guaranteeing economic benefits and normal development of fruits and trees,an irrigation system between C2 and C3 should be selected.(2)Under different irrigation quotas,the correlation between the water content of 10 cm and 20 cm soil layers in the vertical direction is significant.In the depth of 0～60 cm,the correlation between volumetric water content of adjacent soil layers from 0 cm to 30 cm on the side of drip irrigation belt is significant.As the irrigation water increases,the horizontal wetting width and the vertical infiltration depth increase at the same time.With the decrease of irrigation,the horizontal wetting width increases first and then decreases,and the vertical infiltration depth decreases.In the irrigation with plenty of water,the moisture monitoring probes with the depth of 20 cm and 60 cm are reserved in the vertical direction,and the 0 cm and 30 cm moisture monitoring probes are reserved in the horizontal direction.In the medium water irrigation,10 cm and 40 cm depth probes are reserved in the vertical direction,and 0 cm and 15 cm probes are reserved in the horizontal direction.Less water irrigates the probe with 20 cm depth in the vertical direction and 15 cm in the horizontal direction.(3)Jujube tree crown temperature difference(?T)showed a multi-peak curve distribution at each growth period,sunny days,the temperature difference between the crown(?T)change is greater than the cloudy day,should be selected at 14:00 on the sunny days of the crown temperature difference(?T)To predict the status of soil moisture in jujube roots.(4)When the meteorological data is sufficient,the complete forecast model can be used to obtain the soil water status of the jujube tree root area(average relative error MRE ≤ 6 %).When the meteorological data is insufficient,the generalized forecast model can be used within a certain error range.(MRE ≤ 10%)forecast soil moisture status in the jujube tree root zone.(5)When the jujube tree grows in the bud,the flowering stage has a ?T >-2.77 °C,the young fruit’s ?T >-3.35 °C,and the mature period of the ?T >-2.19 °C,the jujube needs irrigation.Temperature difference(?T)< Threshold air temperature difference threshold(?Tr)indicates that jujube does not require irrigation.