Study Response To The Glycyrrhiza Seed Germination And Seedling Growth And Photosynthesis Characteristic Under Salt Stress

Glycyrrhiza is an important plant resource in northwestern China.It has a wide range of medicinal and ecological protection functions.It is of great significance t o study the salt tolerance characteristics of glycyrrhiza to rationally utilize glycyrrhi za resources.In this study,glycyrrhiza seeds and seedlings were used as materials,with different concentrations of NaCl stress(0,100,200,300,400 mmol/L)for seed soaking or irrigation treatment.To study the effect of NaCl stress on the germinati on,seedling growth and photosynthetic characteristics of glycyrrhiza.To provide a basis for understanding the salt-tolerant properties of glycyrrhiza and elucidating its possible cytological mechanism.The main results is:(1)In the water-free control without NaCl treatment,the germination time of glycyrrhiza seeds was short and the germination rate was high.The germination rat e on the 6th day of treatment was 99%;Under different NaCl stress,the germinati on rate and germination process of glycyrrhiza seeds were affected,Among them,t he germination rate and germination time of glycyrrhiza seeds under low concentrati on NaCl(100mmol/L)treatment were not significantly different with CK,Under the 200-400 mmol/L NaCl treatment,the germination time of the glycyrrhiza seeds wa s delayed,the germination index and vigor index decreased,the germ and radicle e longation decreased,and the above changes increased with the increase of NaCl co ncentration.(2)In the water-free control without NaCl treatment,glycyrrhiza seedlings gro w vigorously and have high level relative content water and the content of malondi aldehyde content and electrolyte permeability maintain low level;Under low concent ration NaCl(100mmol/L)treatment,the glycyrrhiza seedlings grew well,the chlorop hyll content was high,the malondialdehyde content and electrolyte permeability incr eased slightly compared with the control,and the relative water content decreased s lightly;With the increase of NaCl treatment concentration and treatment time,the g rowth potential of glycyrrhiza plants decreased,leaf yellowing increased,electrolyte permeability and malondialdehyde content increased significantly,chlorophyll content and relative water content decreased significantly.(3)Under low concentration NaCl(100mmol/L)treatment,the chlorophyll content of glycyrrhiza leaves increased compared with the control;under high concentration NaCl(400mmol/L)treatment,the chlorophyll content decreased significantly.Chlorophyll a/b decreased gradually with the increase of NaCl concentration.At the same concentration,chlorophyll a/b decreased with the extension of treatment time.The minimum daily changes in Pn,Tr,and Gs correspond to the maximum daily changes in light intensity and temperature.Photosynthetic lunch breaks occur.The lower daily changes in Fo,Fv/Fm correspond to the photosynthetic lunch breaks.The smaller the treatment time Fv/Fm,the lower the efficiency of the plant light energy utilization.The Pn changes in the early treatment period(7,14day)were mainly stomatal limiting factors,and the Pn changes in the late treatment period(21,28days)changed from stomatal limiting factors to non-stomatal limiting factors.(4)Without NaCl treatment the carbohydrates of glycyrrhiza leaves maintained a high level;the low concentration(100mmol/L)NaCl stress of all sugars was significantly higher than the control,which was beneficial to the accumulation of carbohydrates;200mmol/L NaCl stress only inhibited sucrose accumulation slightly inhibit glucose accumulation;under 300mmol/L NaCl stress,it is only conducive to starch accumulation;under 400mmol/L NaCl stress,all sugars maintain low levels,which is not conducive to carbohydrate accumulation.Glycyrrhiza seeds can adapt to low concentration NaCl(100mmol/L)stress,and seed germination is significantly inhibited under high concentration NaCl(400mmol/L)treatment.Under low NaCl(100mmol/L)stress,glycyrrhiza seedlings grow vigorously and have high chlorophyll content.Although Pn has decreased,it can still maintain a high level;The growth of plants under 200mmol/L NaCl stress was inhibited,and Pn decreased significantly;The normal physiological function of the plant is destroyed under 300-400 mmol/L NaCl stress,and the growth is poor or even dead.According to comprehensive analysis,glycyrrhiza seedlings have strong adaptability to low concentration NaCl stress(100 mmol/L)and can withstand 200 mmol/L NaCl stress for a short time.