Response Of Lycium Barbarum Growth To Intercropping Alfalfa And Moisture Regulation

Aiming at the serious problems of low exploit rate of water and soil resources,high surface exposure and large evaporation in the Yellow River Irrigation Region of Gansu provice.The water control experiment was carried out to study the intercropping mode and intercropping irrigation system suitable for the irrigation region,in the irrigation test station of Gansu Jingdian Administration.The experiment taked Lycium barbarum and Alfalfa as research objects,and designed two planting modes:single-planting Lycium barbarum(DZ)and Lycium barbarum intercropping alfalfa(JZ),three levels of moisture regulation:full irrigation(F:75%~85%),light deficit(L:65%~75%),moderate deficit(M:55%~65%).Based on the niche theory,the spatial segmentation method was used to analyze the distribution variation and interspecific competition of the aboveground in the intercropping system,and to construct the intercropping mode suitable for the irrigation region.Analyzed the changes moisture,temperature,nutrient,evaporation of soil,photosynthetic,growth and yield of Lycium barbarum under different moisture regulation,and to construct a suitable intercropping irrigation system.The following main conclusions are drawn:(1)The aboveground biomass of Lycium barbarum was mainly distributed in the horizontal range of 0~90 cm from trees and 40 cm away from the ground.The spatial competitiveness of alfalfa in the range of 30~90 cm horizontally and 0~60 cm vertical was higher than Lycium barbarum.The horizontal 0~60 cm was the competitive high-strength area of the above-ground space in the intercropping system.In order to effectively reduce the competition of inter-species space,the alfalfa should planting 60cm away from the Lycium barbarum line.(2)The intercropping the alfalfa increased the soil water content of 0-20 cm,and the average soil water content of 0~120 cm decreased 1.6%~7.1%.Both of intercropping the alfalfa and water regulation reduced soil evaporation,and the declines were 32.21%~36.09%and 10.22%~24.19%.Intercropping increaseed surface coverage,it reached a two-way dynamic control of l soil temperature,increaseed soil temperature stability.Compared with single-planting Lycium barbarum,the soil organic matter increased 9.62%~11.14%,total nitrogen increased 6.09%~7.11%,and effective nitrogen increased by 6.13%~7.02%under intercropping alfalfa mode.(3)The net photosynthetic rate and leaf water use efficiency of the Lycium barbarum were highest at the light deficit,was 17.70?mol/m~2·s and 3.16?mol/mmol,under single-planting Lycium barbarum.The net photosynthetic rate was the highest at the full irrigation,was 18.31?mol/m~2·s,the leaf water use efficiency was 3.21?mol/mmol at the light water regulation under intercropping alfalfa mode.When the moisture regulation was the same,the temperature of Lycium barbarum was decreased under intercropping alfalfa mode,the high temperature stress of Lycium barbarum decreased,and the photosynthetic"noon break"weakened.(4)Under the same moisture regulation,intercropping alfalfa increased the growth of Lycium barbarum about 8.4%~12.9%;the growth of ground diameter increased under full irrigation;crown width,growth and diameter of new branch of Lycium barbarum were significantly reduced under moderate water deficit;the 100-grain weight and yield of Lycium barbarum increased significantly under full irrigation,and decreased significantly under moderate water deficit.Under the single-planting mode,the 100-grain weight and yield of Lycium barbarum increased first and then decreased,and the highest was the slight water deficit.Under the intercropping mode,the 100-grain weight and yield of Lycium barbarum showed a downward trend.(5)There is a quadratic curve between irrigation amount and Lycium barbarum yield and water use efficiency.The yield and water use efficiency decrease with the increased of irrigation amount and then decreased.The water use efficiency was the highest when the irrigation amount was 624.1 mm,and the highest yield was obtained when the irrigation amount was 697.9 mm,the optimal irrigation range is 624.1mm~697.9 mm under single-planting Lycium barbarum.When the amount of irrigation was 763.5 mm,the water use efficiency was the highest.When the irrigation amount was 891.9 mm,the yield was the highest,and the optimal irrigation range is 763.5mm~891.9 mm under Lycium barbarum intercropping alfalfa.