Research On Fine Root Distribution And Water-uptake Model Of Fruit Trees Under Water Storage Pit Irrigation

China is an agricultural country,irrigation water is the main consumption of agricultural water.With the development of economic and expansion of population, contradiction between water supply and demand becomes more and more sharp.Different ways of saving water methods was researched and have made a great of achievement.Due to the geographical differences,development of water-saving irrigation adjust to local conditions is imperative.The orchard planting area in the northwest China is increasing,but less annual rainfall and soil erosion seriously limits its development.In order to solve this problem,professor Sun Xihuan in1998proposed a new method of orchard irrigation-water storage pit irrigation. Water absorption of root distribution must be researched first in order to study mechanism of water-saving irrigation and improve water use efficiency deeply.Soil moisture measurement system(TRIME-PICO IPH) was carried out to measure the soil moisture content.Root length density of apple trees were acquired with root drilling method.Apple trees’roots area and distribution of water within the scope was studied.Root water absorption model is established according to the data of root density.This study enrich the research of root system distribution under the condition of water storage pit irrigation and nutrient research theory basis for further establish of root water absorption model and root zone soil moisture.The results of the study can also provide a reference for other plants absorbing water model.In this paper, the main research results are as follows:(1) The change of soil moisture content within the root zone scope:1)On the vertical,the change of the soil moisture content at different radial along with the change of soil depth is similar.Near the surface,the soil moisture content is low.Soil moisture content are increases gradually with the increase of soil depth.The soil moisture content is not continued to increase but showing a decrease trend when the soil depth reaches a certain value.2)On the radial,the farther away from the water storage pit,the smaller the soil moisture content is.The moisture content of near the water storage pit is larger. Water content of the side close to the tree is larger.3)The vertical distribution of soil moisture with time is roughly same,soil water first increased then decreased with the increase of soil depth. With the passage of time, the water to the soil depth migration,the soil moisture content change reduced due to environmental factors that affect the ability is abate.Range of soil moisture content on radial with depth is accordance.Water migrated from the center of water storage pit and the soil moisture content decreased gradually with time. (2) Distribution of the fruit trees’water absorbing root:1)Under the condition of surface irrigation,the fruit trees’water absorption root increased then decreased in vertical with the increase of depth.0-100cm is the main distribution area.On the radial, the root are mainly distributed in30cm away from the trunk,the farther away from the trunk,fruit trees root length density is smaller.2)Under the condition of water storage pit irrigation,fruit trees root length density in the vertical distribution law of surface irrigation.Root length density increased significantly at the underground60cm,the peak of root length density peak move down compare with ground irrigation.Horizontally,the root density are mainly distributed in the range of30to60cm.3)Both under water storage pit irrigation and ground irrigation conditions,root length density present exponential function relationship with vertical and radial distance.(3)Water uptake model of apple tress’rootThree-dimensional water-uptake model of fruit trees under water storage pit irrigation was established based on the root length density data.The model was verificated with moisture data measured in field.The results show that three-dimensional model built in this paper can be used to calculate water-uptake of fruit trees under water storage pit irrigation.