Water Management Based On Spatiotemporal Dynamics Of Potato Roots Distribution In Soil

The northern Yinshan Mountain in Inner Mongolia is the important potato production area in China,but water resources is defecient in the region.Although drip irrigation mode have been introduced in potato production in recent years and the water and fertilizer use efficiency has been improved to some extent,the potential for water and fertilizer saving has not been tapped enough.Potato is a typical shallow root crop,the root system has weak ability to absorb water and nutrients.Additionally,the soil texture in this production area is sandy with poor water and fertilizer retention capacity.Therefore,understanding the temporal and spatial dynamic distribution of potato root system in soil and the water diffusion and transport in sandy soil,further exploring the spatio-temporal matching between soil water and root system may be a way to improve the water use efficiency in local potato production.In this study,the dynamic distribution of potato roots in the soil was systematically observed,and the soil moisture distribution according to the soil texture was calculated,based on which root distribution oriented irrigation method was designed in keeping total irrigation volume unchanged.Moreover,the plant growth,nitrogen uptake,yield formation,water and nitrogen use efficiency were compared between this irrigation mode and the traditional irrigation mode.The main results of this study were as follows:(1)To improve the efficiency of root length measurement,a new method based on deep learning and computer vision was established.The pearson correlation coefficient between the method and manual measurement is 0.967,the accuracy of root image segmentation was improved and is reliable for the measurement of root length.(2)Large difference existed in root distribution of potato plants at different growth stages in northern Yinshan Mountain in Inner Mongolia.The 80% of potato roots at the seedling stage,tuber formation stage,tuber bulking stage,starch accumulation stage are distributed in the 0-20 cm,0-30 cm,0-40 cm and 0-30 cm soil layers,respectively.(3)The irrigation method based on root distribution which increased potato leaf area index by 10%-20%? dry matter accumulation by 7%-14% and nitrogen accumulation by11%-19%,finally increased potato yield by 7%-12%,water use efficiency by 14%-19%.The irrigation method reduced the residual nitrate nitrogen after potato harvest in40-60 cm,60-80 cm and 80-100 cm soil layer by 24%,36% and 37%,respectively.(4)In the northern Yinshan Mountain in Inner Mongolia,20% of the nitrogen fertilizer can be reduced by irrigation method based on root distribution,and the partial nitrogen productivity of potato can be increased by 24%-26%.In summary,this project revealed the dynamic distribution characteristics of potato roots in soil at different growth stages in the northern Yinshan Mountain in Inner Mongolia,established an irrigation method based on root distribution.The yield and water and nitrogen efficiency were significantly improved in the irrigation method,indicating that it is worthy for promotion and application in local potato production.