| Eremochloa ophiuroides(Munro)Hack.is an excellent warm-season turfgrass originated in China.It has many advantages,such as strong resistance,low maintenance,low nutrient requirements,long green period and with high ornamental value.It is an ideal plant material for all kinds of lawns,slope protection and embankment protection,and has great development potential.Drought is the most common abiotic stress in the natural environment and it causes the leaves to lose water,photosynthesis was inhibited,plant was stopped to grow,and even die.5-aminolevulinic acid(5-ALA),as a natural plant endogenous hormone,has the advantages of promoting plant vegetative growth,improving crop yield and quality,and alleviating the damage caused by abiotic stress on plants.It has broad application prospects in the agricultural field.Now,the research of 5-ALA to improve plant resistance mainly focuses on crops such as tomato,apple and wheat,and there are few related researches on turfgrass plants.This paper chosen Eremochloa ophiuroides as the test material.The effects of5-ALA on plant morphology,photosynthesis,osmotic adjustment substances and antioxidant enzyme activities under drought stress were studied by spraying 5-ALA at a concentration of 50 mg/L on Eremochloa ophiuroides and to explore the regulation mechanism of 5-ALA on drought resistance of Eremochloa ophiuroides and to provide theoretical basis for the application and promotion of 5-ALA in turfgrass conservation management.Summarizes the results of this study below:(1).Under drought stress,the leaves of Eremochloa ophiuroides lost water and wilted,and the plants grew stagnant,which showed obvious symptoms of drought.Scanning electron microscopy showed that the surface of the Eremochloa ophiuroides under drought stress had a small amount of unknown impurities and the pores were closed.However,spraying 5-ALA could significantly reduce the damage of Eremochloa ophiuroides caused by drought stress.Its leaf and plant wilting degree was reduced.The surface of the leaf was smoother and cleaner.On the 30 th day ofdrought stress,the transverse diameter of the stomata was 11.95% larger than that of natural drought,and the stomata longitudinal stem was 6.15% smaller than that in the case of drought.After rewatering,the leaves and plant morphology of Eremochloa ophiuroides sprayed with 5-ALA were highly restored.(2).Drought stress inhibited the photosynthesis of Eremochloa ophiuroides,and decreased the relative water content(RWC),chlorophyll content(Chl),net photosynthetic rate(Pn),transpiration rate(Tr)and stomatal conductance(Gs)of leaves.5-ALA significantly increased the RWC,Chl,Pn,Tr and Gs of Eremochloa ophiuroides under drought stress.After rewatering,Pn,Gs and Tr in the 5-ALA treatment group were closer to the control level than the natural drought group.Transmission electron microscopy showed that under drought stress,with the deepening of drought stress,the cell membrane structure of Eremochloa ophiuroides gradually lost its integrity,the chloroplast membrane and thylakoid membrane ruptured,the chloroplast swollen and disintegrated to disintegration.Spraying 5-ALA could effectively alleviate the damage of leaf cell membrane structure under drought stress.The chloroplast structure of Eremochloa ophiuroides was complete and the thylakoids were arranged in order.(3).On the 30 th day of drought stress,compared with the natural drought group,the malondialdehyde(MDA)content,the relative conductivity,and the soluble sugar content of the Eremochloa ophiuroides leaves in the 5-ALA pretreatment group decreased by 19.27%,13.23%,and 16.72%,respectively,the soluble protein content increased by 8.71%.It indicates that 5-ALA treatment reduced membrane permeability of leaf cells under drought stress and oxidative damage caused by drought stress.5-ALA treatment could actively participate in the regulation of osmotic regulation of cells and improve the ability of sugar transportation in plants under drought stress,increase the drought resistance of Eremochloa ophiuroides.(4).During a certain drought period,the activities of superoxide dismutase(SOD),catalase(CAT)and peroxidase(POD)in the leaves of Eremochloa ophiuroides increased significantly with the deepening of drought stress.On the 20 th day of drought stress,compared with the natural drought group,SOD,CAT,POD ofEremochloa ophiuroides leaves sprayed with 5-ALA pretreatment group increased14.55%,7.59% and 25.05%,respectively,which indicated that 5-ALA could alleviate the oxidative damage of reactive oxygen species(ROS)accumulation caused by drought stress by increasing the antioxidant enzyme activity in Eremochloa ophiuroides. |
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