Effect Of Salt Stress On Physiological Characteristics And Root Exudates Of Echinochloa Frumentacea(Roxb.) Link During Seedling Stage

Saline soil is a soil type that widely exists throughout the world and has a significant impact on land use and agricultural production.This study is based on the main salt composition characteristics of salinealkali soils in the northern irrigation area of Ningxia.Using the salt-tolerant forage grass,Echinochloa frumentacea(Roxb.)link,as the experimental material,two methods of soil cultivation and hydroponics were designed.The neutral salt(NaCl+Na2SO4)was used for stress treatment,with a molar concentration of 1:1,and six concentrations were set at 0(CK),30,60,100,220,and 340 mmoL·L-1.By analyzing the growth indicators,photosynthetic physiological parameters,leaf sugar,organic acid and proline contents,ion absorption,transport and accumulation characteristics,root hormone content,and root exudate types and contents under different concentrations of salt stress,the salt tolerance mechanism of Echinochloa frumentacea(Roxb.)link during the seedling stage was elucidated.The physiological significance and ecological effects of the root exudates of Echinochloa frumentacea(Roxb.)link under salt stress were explored,providing a theoretical basis for using salt-tolerant crops for bioremediation of saline-alkali soils.The main conclusions are as follows:1.Salt stress affects photosynthesis,growth,and biomass of Echinochloa frumentacea(Roxb.)link during the seedling stage,inhibiting the accumulation of leaf fructose,sucrose,and malic acid,while promoting the accumulation of citric acid,tartaric acid,and proline.2.As the concentration of salt treatment in the soil increases,the ability of Echinochloa frumentacea(Roxb.)link roots to absorb K+and exclude Na+ is enhanced,and the leaves and roots of the plants maintain higher levels of Ca2+content.3.Salt stress causes an increase in ABA and tZT content in the roots of Echinochloa frumentacea(Roxb.)link during the seedling stage.There is an increase in the secretion of terpenoid compounds by the root system,and low concentrations promote while high concentrations inhibit the secretion of tartaric acid by the roots.In summary,under different concentrations of salt stress,Echinochloa frumentacea(Roxb.)link during the seedling stage employ various physiological mechanisms to adapt to saline conditions.These mechanisms include increasing intercellular CO2 concentration in the leaves to accumulate osmotic regulatory substances,enhancing the content of ABA and tZT in the roots to upregulate the secretion of terpenoid compounds and promote the secretion of tartaric acid by the roots.Additionally,the plants utilize the root system’s strong selective absorption and transport capacity to maintain higher levels of Ca2+content in both leaves and roots.These physiological adaptations enable the plants to cope with saline stress.