Effects Of Irrigation Intensity On Physiological Characteristics And Fruit Yield And Quality Of Pear-jujube

Ten years old pear Jujube trees as the experimental materials, were irrigated in five treatments, five repeat. According to the physiological and growth characteristics of jujube tree, the growth stage of pear-jujube tree is divided into: flowering reason, fruit setting stage, fruit expanding stage, fructescence and fruit ripening period. In this paper, photosynthetic characteristics, yield, quality under different irrigation treatments and photosynthesis, transpiration factors, water consumption under natural conditions of pear jujube tree in different stages were studied. The results obtained are as follows:1) Throughout the growth period the leaf area index of pear-jujube tree increased at first, then gradually stabilized, and finally decline; on early growth stage of jujube leaves irrigation had no obvious effect on leaf area index; from late of fruit expanding stage to the beginning of fructescence, the canopy of jujube tree growth rapidly, leaf area index has risen sharply. At this stage with the increase of irrigation the leaf area index increased. In fructescence leaf area index basically unchanged, to the late of fructescence the jujube trees into the leaf fall period, the leaf area index started to decline.2) In the entire trial period the chlorophyll content of pear-jujube tree leaves is increased firstly and then decreased. Initial increased soil moisture was little effect on leaf chlorophyll content; In fruit setting stage a small amount of irrigation can increase the leaf chlorophyll content of jujube tree, excessive irrigation would decreased the chlorophyll content. In fruit expanding stage the irrigation treatments can significantly improve the chlorophyll content of pear-jujube tree leaves. In fructescence irrigation had little effect on the chlorophyll content of pear-jujube tree leaves.3) In addition to the fruit picking period, in other periods net photosynthetic rate during the irrigation treatments were significantly higher than control treatment. In all stages jujube leaf net photosynthetic rate first increased with the irrigation water and then decreased. Proper irrigation can improve the net photosynthetic rate of pear-jujube tree, but more than a certain amount of irrigation, irrigation was not beneficial to increase the photosynthetic of pear-jujube tree. Most of the stages photosynthetic ability of pear-jujube tree was higher during the morning than in the afternoon; Improve soil moisture can increase water use efficiency of pear-jujube tree leaves, but the change did not significantly like net photosynthetic rate; Preliminary draw that T3 treatment of irrigation to 45% of field capacity is benefit to jujube tree photosynthesis.4) With the increase of soil moisture, leaf light saturation point of pear-jujube tree increases. That is the increase in soil moisture increases the jujube leaf on light demand. Meanwhile, the modest increase in soil moisture can reduce the light compensation point, is conducive to the use of low light, but the excessive increase in soil moisture was to make the light compensation point increased. Soil moisture change at different times with the apparent quantum efficiency changes of pear-jujube tree leaves is inconsistent.5) Different irrigation has effect on jujube yield to a certain extent. Appropriate irrigation can increase yield of jujube. But excess irrigation in increase production was not obvious, and even cut production of the jujube trees.6)Irrigation can increase the soluble solid of jujube fruit, Vc, soluble sugar and reducing sugar content. However, soluble solids, Vc and soluble sugar content increased required the irrigation within a certain range, beyond the scope of that range its content is not only not increase or even decreasing. Increased soil moisture cannot improve the citric acid content of fruit significantly, even if irrigation excessive the citric acid content of fruit would reduced.7) Analyzing the path coefficients between photosynthesis, transpiration and impact factors of pear-jujube under natural conditions in different periods obtained the following aspects. Relative humidity of the atmosphere was the main factors affecting the photosynthesis of pear-jujube tree. In flowering reason and fruit setting stage RH had a positive correlation with the photosynthesis of pear-jujube tree, in the fruit expanding stage and fruit ripening period it was not conducive to photosynthesis of pear-jujube tree. Only in fructescence the RH had little effect on photosynthesis. Light intensity was the main factors affecting transpiration all the time. In flowering reason, fruit expanding stage and fruit picking period, light intensity and transpiration were positively related. In fruit setting stage and fructescence they had negative correlation.In flowering reason, high temperature limits the photosynthesis potential of pear-jujube tree. In fruit setting stage reduce the CO₂ concentration will increase the photosynthetic capacity of jujube tree. In fruit expanding stage, promoting stomatal opening, increased atmospheric CO₂ concentration of jujube tree leaves can increase the photosynthetic production. In fructescence, promote stomatal opening can enhance photosynthetic capacity of pear-jujube tree. In fruit ripening period, reducing the air humidity can increase the photosynthetic rate of pear-jujube tree.8) Calculated the transpiration of pear-jujube trees and rainfall data in2010, obtained that for meet the transpiration of pear-jujube leaves, needs of 22.4, 50.2 and 28mm irrigation in June, July and October, while in August and September with a surplus of water.Within the appropriate range of irrigation can increase the jujube leaf area index, chlorophyll content, photosynthetic capacity and improve the jujube fruit quality. Comprehensive draw that in flowering reason, fruit setting stage and fruit expanding stage, the irrigation to 45% of field capacity, is conducive to improvement the photosynthetic capacity of pear-jujube tree leaves, in fruit picking period irrigation the various indexes of treatments and the control had little difference, so do not need irrigate.