Effects Of Fulvic Acid On Salt Tolerance Of Malus Hupehensis Rehd And Malus Robusta Rehd

Using Malus hupehensis Rehd.and Malus robusta.Rehd,common rootstocks used in apple production,as test materials,this test studied the effects of fulfuric acid and its mixture with auxin on seedlings of two common stocks used in apple production under 0.3%saline-alkali stress simulated by NaCl and NaHCO₃.The results are as follows:（1）Fulvic acid was applied to roots at different concentrations:0 mg·L^-1,500 mg·L^-1,800 mg·L^-1,and 1000 mg·L^-1.Among them,500 mg·L^-11 fulvic acid root application treatment can significantly improve the activity of SOD and POD in the root system of Malus hupehensis Rehd.seedlings and reduce the content of MDA,indicating that it can enhance the root tolerance of Malus hupehensis Rehd.seedlings and slow down the aging of the root system.The activity of SOD and POD in the root system of the seedlings was also increased and Malondialdehyde was decreased to some extent.（2）In Malus hupehensis.Rehd.seedlings as test materials,studied in neutral salt（NaCl）and 0.3%of alkaline salt（NaHCO₃）hybrid simulation of salinity-alkalinity stress conditions,different concentration of fulvic acid（FA）are improved the Malus.Robusta seedling leaf chlorophyll content and water use efficiency,increased the SOD,POD activity,increased the root activity,reduce the content of malondialdehyde,increased the root length,surface area,volume,average diameter,number of root tip.And root structure,root activity,antioxidant enzyme,malondialdehyde content.Applying 500 mg·L^-1of fulvic acid to the root of Malus.robusta seedlings significantly improved root activity,enhanced root SOD and POD activity,reduced malondialdehyde content,promoted root growth and root branching,increased leaf chlorophyll content,and improved leaf water use efficiency.Xanthofuric acid treatment could improve the antioxidant capacity of the root system of Malus hupehensis Rehd.seedlings to resist the damage caused by salt stress.（3）The combination of fulvic acid with NAA and IBA had a great effect on the salt tolerance of the root system of Malus hupehensis Rehd.Seedlings.Among them,the combination of xanthofuric acid(500 mg·L^-1)and IBA(1 mg·L^-1)increased root activity,total root length,surface area,volume,average diameter and number of root tips,increased root antioxidant enzyme SOD activity by 34.26%,POD activity by 13.67%,and soluble protein content by 55.36%.This indicated that the salt-tolerance of Malus hupehensis Rehd.seedlings was improved by the ratio of fulvic acid and IBA at the appropriate concentration.However,the ratio of 500 mg·L^-11 fulvic acid to 1 mg·L^-11 NAA（M8）showed little difference from the control group.（4）Under the salt stress,different concentrations of Fulvic acid had a great influence on the root growth and salt-tolerance of the seedlings of Malus hupehensis Rehd.And Malus.Robusta.The results showed that the xanthic acid treatment of 500 mg·L^-1significantly increased the activity of SOD,POD and CAT enzymes in the root systems of Malus hupehensis Rehd.saplings and Malus robusta.Saplings,the content of MDA was lower than that of other treatments,the content of soluble protein was also higher than that of other treatments,and the net photosynthetic rate of above ground part was also significantly increased.To sum up,500 mg·L^-1of xanthofuric acid can significantly promote root growth,improve root vitality,enhance root salt-tolerance,and promote photosynthesis in above ground parts of Malus hupehensis Rehd,saplings and Malus.Robusta.saplings,and Malus robusta.Rehd The salt tolerance of sea otter saplings is stronger than that of sapling Malus hupehensis Rehd.