Response mechanism of Lycium ruthenicum root architecture to drought stress

【Objective】To investigate response mechanism of root architecture of Lycium ruthenicum seedlings to drought stress，so as to provide scientific theoretical basis for planting，population restoration and appropriate utilization of L.ruthenicum and study on other xerophytic plants.【Method】 Potted L.ruthenicum seedlings were taken as research object，and water control method was used to set 5 stress gradients： normal water supply （20.97%）（control，CK），mild stress （15.51%），moderate stress（3.42%），severe stress（2.35%）and extremely severe stress（1.45%）.Through comparing root topology index，topological structure，biomass and relative root morphological indexes of L.ruthenicum seedlings，zzthe response of root architecture of L.ruthenicum seedlings to drought stress was analyzed.【Result】 Under drought stress，the root structure of L.ruthenicum suited forked branch model.With the increase of the degree of drought stress，the root of L.ruthenicum seedlings transitioned from forked branch to fishtail branch；above-ground biomass，below-ground biomass and total biomass of the seedlings increased first and then decreased，and there were significant differences in aboveground biomass and total biomass among different treatments（P<0.05）.Compared with CK，the total biomass under mild and moderate stress increased by 82.47% and 41.09%，respectively.root-shoot ratio gradually increased； root length，root surface area and root volume all first increased and then decreased；specific root length and specific surface area decreased gradually： in mild，moderate，severe and extremely severe stress specific root length decreased by 7.73%，10.25%，60.62% and 77.09%，and specific surface area decreased by 17.59%，30.04%，80.15% and 83.40%，respectively.Root length，root surface area and root volume of different diameter classes all reached the maximum value under mild stress.The order of root length and root surface area with the increase of drought stress was 0-0.5 mm>0.5-1.0 mm>1.0-1.5 mm> 1.5-2.0 mm>2.0-2.5 mm.【Conclusion】Growth of L.ruthenicum is affected by drought stress，and there are differences between different morphological indexes and root architecture.Mild drought stress is conducive to the growth of the root of L.ruthenicum seedlings，but there is a threshold for the tolerance of L.ruthenicum，and the growth is best when the soil water content is 15.51%.