Physiological Mechanism Of Dopamine And Ascorbic Acid Alleviate The Effect Of Salt Stress In Apple

With the aggravation of global climate change,soil salinization has become a major problem affecting ecology and agriculture.Apple is a non-halophyte sensitive to salt,and salt stress will affect its growth and development through ion poisoning,oxidative stress and so on.It is mainly manifested in restricting tree growth,reducing fruit yield and quality,and even causing lose production or die.M9T337 is widely used in the construction of modern dwarf and densely planted apple orchards.However,there is still a lack of understanding about the salt resistance of M9T337,which will limit its use in saline-alkali areas.Ascorbic acid and dopamine have strong antioxidant activity and can improve the ability of adversity.Therefore,in this study,M9T337 seedlings were used as test materials to evaluate the salt resistance of M9T337 through pot experiments,and the effects of dopamine and ascorbic acid on the growth,photosynthesis,chlorophyll content,root architecture and antioxidant capacity of M9T337 seedlings under salt stress were studied.The appropriate concentration of dopamine,ascorbic acid and the two used together was screened to alleviate the influence of M9T337salt stress.The results of the study are as follows:1.M9T337 seedlings were treated with salt stress,the photosynthetic capacity of leaves decreased,the content of chlorophyll decreased,as well as inhibiting root growth,the antioxidant capacity of plants was reduced,and the growth of M9T337 seedlings was stunted.2.Under salt stress,applying dopamine or ascorbic acid could effectively alleviate the damage to M9T337 seedlings and enhanced the salt resistance of M9T337 seedlings.Compared with the control,dopamine or ascorbic acid treatment significantly increased the photosynthetic capacity of M9T337,alleviated the decomposition of chlorophyll in the leaves of M9T337 under salt stress,positively regulated root growth,increased the antioxidant enzyme activity in the body,inhibited the accumulation of MDA and H₂O₂,and reduced the growth of seedlings.Oxidative damage and membrane lipid peroxidation.Screening the best dopamine concentration for alleviating M9T337 salt stress was 50μmol/L,and the best ascorbic acid concentration was 4 mmol/L and 6 mmol/L.3.The compound treatment at the appropriate concentration selected through the preliminary experiment.Compound treatment of different concentrations had different mitigation effects on the salt stress of M9T337 seedlings,and had different effects on growth,photosynthetic pigment,root imaging and root configuration parameters,etc.The impact of indicators was also different.It was also found that after the compound treatment,the H₂O₂content was reduced to varying degrees compared with the salt treatment,and the activities of enzymes such as CAT were significantly higher than that of the salt treatment.According to the experiment,the optimal concentration of dopamine and ascorbic acid was 50μmol/L dopamine and 6 mmol/L ascorbic acid.