The Response Of Glycyrrhiza Uralensis To Drought And Re-water And The Comparison Of The Main Nutritional Components Of Glycyrrhiza Uralensis In Different Germplasm

Glycyrrhiza uralensis Fisch,a perennial herb of the leguminous family,has strong adaptability,drought and cold tolerance.Its aboveground tufted branches and leaves have high content of protein,fat and other nutrients,and have high feeding value.Glycyrrhiza uralensis is widely distributed in sandy land,saline-alkali grassland and other areas in the west of Northeast Plain of China.However,at present,there are few cultivars of licorice,and the research on forage is insufficient,which limits the effective utilization of licorice.Therefore,it is of great significance to study the difference of feeding quality of different licorice germplasm resources and their response to drought stress and rehydration for cultivating high-quality artificial licorice varieties and improving the availability of some resources on licorice grassland in Northeast semi-arid region.Seven different licorice germplasm resources were collected and compared in terms of their production characteristics and nutrient components.The optimal licorice germplasm resources were studied under drought stress(soil water content was 80%-85%,mild drought 60%-65%,moderate drought 40%-45%,severe drought 20%-25%)and rehydration.The results show that:(1)The feeding quality of wild licorice resources in Western Jilin Province is the best,the ratio of stem to leaf is low,and the content of neutral detergent fiber in stems and leaves is 23.28%,3.66%,17.52%,15.81%,10.96% and 9.24% lower than that in other areas,respectively.The content of acid detergent fiber is 10.88%,1.78%,15.91%,18.4,6.92% and 3.99% lower than that in other areas.The protein content in leaves was 30.58%.(2)Drought stress significantly inhibited the growth of the upper and underground parts of Glycyrrhiza uralensis.Compared with the control,the dry weight of root decreased by 11.6%,36.1%,41.5%,and the dry weight of crown decreased by 9.5%,35.7% and 43.8%,respectively.After re-watering,plant height,stem-leaf ratio and aboveground and underground biomass of Glycyrrhiza uralensis seedlings under mild drought stress and moderate drought stress recovered significantly.Licorice seedlings under mild drought condition recovered to the control level,while the biomass of Glycyrrhiza uralensis seedlings under severe drought condition and stem-leaf ratio did not recover significantly after re-watering.(3)Drought stress significantly inhibited stomatal conductance,intercellular carbon dioxide concentration,transpiration rate and net photosynthetic rate of Glycyrrhiza uralensis leaves.Compared with the control,stomatal conductance decreased by 21.2%,37.9%,42.8%,intercellular carbon dioxide concentration decreased by 15.6%,20.5%,40.4%,transpiration rate decreased by 21.0%,35.0%,43.2%,and photosynthetic rate decreased by 11.1%.35.8% and 38.5% respectively.After re-watering,under mild drought stress,the photosynthetic parameters of the leaves of Glycyrrhiza uralensis seedlings restored to the control level,while under severe drought stress,the photosynthetic parameters of the leaves of Glycyrrhiza uralensis seedlings only recovered slightly.(4)Drought stress increased the minimum fluorescence yield to 360 under severe drought stress,and decreased the maximum fluorescence yield to 1780 under severe drought stress.After rehydration,the chlorophyll fluorescence indexes recovered to varying degrees.The initial fluorescence Fo,maximum fluorescence Fm,Fv/Fm,photochemistry quenching coefficient and non-photochemistry quenching coefficient all reached the control level after rehydration,and the maximum fluorescence Fm exceeded the control level.Glycyrrhiza uralensis could not recover to normal level under moderate and severe drought stress,especially under severe drought stress.(5)The content of soluble sugar and proline in leaves of Glycyrrhiza uralensis.increased significantly under drought stress.The highest concentrations were 510.g-1 and 26,000 ug.g-1 under severe drought stress,respectively.After re-watering for a period of time,the concentration of proline and soluble sugar decreased significantly.Under mild drought stress,the concentration of proline and soluble sugar in licorice leaves decreased by 62.3% and 37.5%,respectively,compared with that before re-watering,and returned to the control level.Licorice also decreased significantly under moderate drought stress,but only slightly under severe drought stress.This indicates that after mild or moderate drought,osmotic adjustment substances in licorice can recover in a short time,but severe drought stress will cause irreversible damage to growth.This experiment found that the forage quality of wild licorice resources in Western Jilin Province was the best.After drought stress and re-watering,it was found that the local wild licorice had strong drought resistance.Mild drought stress had a slight inhibition on the indicators,which could be restored to the control level after re-watering.Moderate drought stress and severe drought stress had a strong inhibition on the indicators.Moreover,all the indexes did not recover significantly after re-watering under severe drought stress.