Study On The Effect Of Different Concentrations Of Strigolactones On The Salt Resistance Of M9T337 Apple Rootstock

Apple is one of the important fruit tree crops in the world,but it is easily affected by adverse environments throughout its growth process.Soil salinization has the most serious impact on it,severely limiting the development of the apple industry.Soil salinization,also known as salt stress,can destroy the permeability of plant cells and the relative balance of ions,inhibit plant growth and development,and reduce the quality and yield of crops.It is one of the main non Biotic stress.The salt resistance of apples is medium among deciduous fruit trees.At present,artificial application of exogenous hormones is one of the most effective measures to improve the salt resistance of apples.The hormones involved in apple stress response mainly include Abscisic acid(ABA),Polyamine(PA),Ethylene(eth),Jasmonic acid(JA)and Salicylic acid(SA).These hormones have been extensively studied in plant stress response.In recent years,Strigolactones has been identified as a new plant hormone and can enhance the plant’s stress resistance.This study used M9T337 apple rootstocks as experimental materials to investigate the effects of different concentrations of exogenous Strigolactones(GR24)and Strigolactones inhibitors(Tis-108)on their salt resistance.The research results are as follows:1.Under the stress of 200mmol/L Na Cl solution,the growth of M9T337 apple rootstocks was inhibited,and the leaves gradually showed shrinkage and browning with the increase of treatment time.The net photosynthetic rate(Pn)and stomatal conductance(Gs)significantly decreased,the intercellular carbon dioxide concentration(Ci)increased,and the chlorophyll content decreased.The application of exogenous GR24 significantly improved the development of apple leaf structure under salt stress,increased leaf chlorophyll content and net Photosynthetic efficiency,and significantly promoted stomatal conductance and transpiration rate.The leaf structure of apple rootstocks treated with 1mg/L GR24 was the most complete,and Photosynthetic efficiency was the highest.2.Under the stress of 200mmol/L Na Cl solution,the application of exogenous GR24 can effectively alleviate the inhibitory effect of salt stress on the root growth and development of M9T337 apple rootstocks,promote the growth of main roots,and inhibit the growth of lateral roots.The best treatment effect is at a concentration of 1mg/L GR24.3.Under the stress of 200 mmol/L Na Cl solution,the content of hydrogen peroxide(H2O2)in the leaves of M9T337 apple rootstocks showed an upward trend with the increase of treatment time,and was positively correlated with time.The content of malondialdehyde(MDA),superoxide dismutase(SOD)activity,peroxidase(POD)activity,and catalase(CAT)activity in the leaves showed a trend of first increasing and then decreasing with the increase of salt stress time.The application of exogenous GR24 can reduce the content of H2O2 and MDA in the leaves of apple rootstocks,enhance the activities of SOD,POD,and CAT in apple rootstocks,and the best concentration of 1mg/L GR24 can alleviate salt stress in apple rootstocks.4.Under the stress of 200mmol/L Na Cl solution,Strigolactones can improve the environment of soil microorganisms,reconstruct the composition of soil microbial communities,recruit unique microbial communities,and change the diversity of microbial communities.