Effects Of Sand-Buried And Drought Stress On Annual Herbaceous Plants In Desert-Oasis Ecotone

Annual herb is desert oasis ecotone artificial sand-fixation invasion of constant has formed by the plant after the completion of the vegetation layer,desert oasis transition zone is artificial sand-fixation plant community taxa,the advantage of the herb layer,because severe sandstorm activities and rainfall,sand buried and drought become key to select annual herbaceous plants survival motivation factors Based on the hexi corridor oasis transition zone of the typical annual herb Setaria viridis,Chloris virgata,Halogeton arachnoideus and Bassia dasyphylla were used as research subjects.Seven sand burial depth tests were conducted at 0(CK)1 2 3 5 10 and 15 cm.The interactive experiment of 0(CK)5,10 and 15 different quantities of Caragana korshinskii seeds and 0%(CK)2%,5%,10% and 15% different gradient of drought stress was conducted to explore the effects of sand burial depth and drought stress on annual herbaceous plants.The research results showed that:(1)4 kinds of annual herb plants had the highest emergence rate at a depth of0?1cm,the maximum emergence depth of S.viridis was 10 cm,C.virgata and B.dasyphylla 5cm,and H.arachnoideus 3cm.The growth(plant height and total biomass)and reproduction(number of seeds and 100-seed weight)of the four annual herbaceous plants were high in 2?3cm.(2)Under different sand burial depths,the content of osmotic adjustment substances(soluble sugar,soluble protein and free proline)of four annual herbaceous plants reached the highest at 2?3cm,and malondialdehyde(MDA)the high content was mainly located at the depth of 3?5cm,the chlorophyll content was the highest at1?2cm,and then started to decreased after 2cm.Correlation analysis showed that the growth and survival of annual herb plants are extremely significantly correlated with free proline and chlorophyll content The relationship showed that the two played a more critical role in maintaining plant leaf water balance,ensuring photosynthesis,and maintaining normal plant growth.The research can provide a scientific basis for the restoration of annual herbaceous plants in the desert-oasis ecotones.(3)The number of C.korshinskii seeds significantly affected the germination rate and germination rate of the four annual herbs(P<0.05),and the germination effect was the best when there was no C.korshinskii seeds.The biomass was the highest under 2% drought stress,which indicated that a small amount of drought stress(2%)was beneficial to seedling growth.The root-shoot ratio increased with the increase of drought stress.Seedlings could adapt to drought environment by increasing biomass allocation in roots.(4)With the increase of the number of C.korshinshinii seeds and drought stress,the root activity and chlorophyll content of the four annual herbaceous plants were the highest under normal water condition with the increase of the number of C.korshinshinii seeds.Then,the root activity of the underground part decreased and the photosynthetic capacity of the aboveground part decreased with the aggravation of drought stress,which jointly inhibited the seedling growth.Two-way ANOVA showed that the growth(biomass,root-shoot ratio)of Chenopodiaceae was significantly affected by the interaction between the number of C.korshinskii seeds and drought stress(P<0.05),which may be an important reason for the survival rate of Chenopodiaceae to be lower than that of Gramineae.(5)In summary,annual herbaceous plants can quickly seize the suitable germination conditions to occupy the favorable habitat.However,there are differences between Gramineae and Chenopodiaceae: Gramineae plants are more resistant to sand burial and drought stress,in the succession of vegetation community is affected by the perennial shrub smaller,making its survival and reproduction ability is stronger,is the pioneer in annual herb plant species,and chenopodiaceae plants are better at showed a delayed germination of mechanism,will be retained part of seeds in soil seed banks,to hold the power of long-term survival in harsh environments.This study can provide a scientific basis for desert plant population renewal and vegetation restoration and reconstruction in sandy land.