| This paper takes Chinese jujuba (Ziziphus jujuba Mill. var. Junzao) as research subject, and the experimental treatments of cleaning tillage and covering straw was adopted in the Chinese jujuba yard of Aksu city. To provide the theoretical support for water-saving irrigation technology, the method of TDP(Thermal Dissipation Sapwood Fiow Velocity Probe) and PSYPRO was used to compare dynamic changes of sap flow and leaf water potential in this paper. The main results were as follow:(1)From the daily variation, sap flow of the sunny days between the measures of cleaning tillage and covering straw were the same, which showed single-peak curve. No matter what cloudy days or rainy days, the sap flow of the measures of cleaning tillage and covering straw were the same, which showed unregular excessive-peak curves. From the monthly variation, the variation curves of May, July and October were single-peak, wide-peak and narrower-peak respectively. From July to September, the sap flow of both treatments was still active at night, which could supplement the lost water and keep water balance. From leaf water potential, both daily average variations were all single-valley curves, then both seasonal average variations were V-shape curves. This was a combined function of both internal and external factors, and reflected one of physiological characteristics of Chinese jujuba adaptable to the local site.(2)From April to October, both sap flow velocity of treatments were not obvious difference in the sunny night. From May to August, both sap flow velocity of treatments showed obvious difference, the measure of covering straw was faster than the measure of cleaning tillage on sunny days. From April to October, both treatments showed unobvious difference on cloudy days or rainy days, they did not have unragular starting time or stopping time. From average monthly sap flow velocity and accumulative stem sap flow, the measure of covering straw was higher than the measure of cleaning tillage except April and October during the growing season. From the variation of daytime and season, the leaf water potential of the measure of covering straw was higher than the leaf water potential of the measure of cleaning tillage.(3) The dynamic trench of average sap flow velocity became smooth and steady between both treatments in successive sunny days, which mean the tree grows well. The sap flow of both treatments could reflect the environmental factors change timely, to some extent, this factors included air temperature, air humidity and the sun total radiation that impacted on sap flow velocity on cloudy days, while the result was opposite on rainy days. The sap flow velocity of the measures of cleaning tillage and covering straw were related to rainfall. When it rains, both sap flow velocity become slow suddenly, and then become normal. The sap flow velocity of the measures of cleaning tillage and covering straw were not well correlated with environmental factors in spring, while the correlation enhanced in summer. On this condition, the change of environmental factors became steady, the air humidity, wind speed, soil temperature and soil water potential impacted on the sap flow increasingly. Both sap flow maintained at a certain level in autumn, but both sap flow were not well correlated with environmental factors. Leaf water potential had a negative correlation to air temperature and total solar radiation, and a positive correlation to air humidity. Evident positive correlation existed between the variation of leaf water potential and soil water potential, and linearity correlation existed between leaf water potential and sap flow velocity. The transpiration went up and the leaf water potential went down while the soil water potential decreased, the leaf water potential was still lower when the transpiration and the soil water potential increased, the leaf water potential recovered when the transpiration decreased. This provided a scientific basis for understanding water situation in the body of Chinese jujuba and selecting physiological indicators for rational irrigation.(4)Under the condition of both treatments, changing trends of daily variation of sap flow velocity and leaf water potential were related to total solar radiation, air temperature and relative humidity obviously. The main environmental factors which were total solar radiation and air temperature impacted on sap flow velocity and leaf water potential obviously. The air humidity and soil water potential is major factors that affected sap flow and leaf water potential. During the growing season, water consumption of Ziziphus jujuba of the measures of covering straw and cleaning tillage were214.290L and134.745L. Water consumption of the measure of covering straw was more than the measure of cleaning tillage79.545L, which was lost by the measure of cleaning tillage. At last, the measure of covering straw was used for decreasing evaporation of soil moisture content. |
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