Effect Analysis And Physiological Mechanism Of Exogenous Algae Fertilizer To Relieve Salt Stress In Tomato Seedlings

It will cause great harm to the vegetables if the soil contains high concentrations of Na⁺.Also,it would lead to the toxic action of the single ion,nutritional deficiency,osmotic stress,etc.due to the imbalance of ions.As a result,growth and total absorption area of the plant root may be restrained with the increase of membrane permeability and decrease of water absorbing capacity.This will have severe effects on the vegetables'root nutrient and water utilization efficiency as well as the sustainable development of facility cultivation.The economic benefit would be damaged seriously for the further consideration.Previous research works have been demonstrated that trehalose could effectively enhance its growth and development,haste maturity,boost production and improve quality.However,the specific mechanism is still unclear.Here we reported the remission effect of salt stress by trehalose and the regulatory mechanism in this research project.This experiment used pot-culture method to analyze indicators related to the NaCl stress,including the influence of trehalose on tomato seedlings in terms of growth,root activity,MDA,redox signaling and antioxidant enzyme activities.The results showed that using 2g/L trehalose could partial remission the oxidative damage on tomato seedlings from 200nmol/L salt stress.Under the NaCl stress,plant height,stem diameter,biomass,chlorophyll synthesis and root activity of tomato seedlings were significantly inhibited.Compared with the salt-stress treatment,the plant height and stem diameter under the salt-stress treatment were increased by 307.68%and 419.60%,respectively,and the fresh and dry weight of the crown,root and dry weight,root and crown ratio,total fresh weight and total dry weight were increased by 23.42%,15.86%,46.91%,41.38%,16.82%,26.42%,27.05%and 20.81%,respectively.Compared with NaCl stress treatment,the total amount of chlorophyll a,chlorophyll b and chlorophyll in the pretreatment with seaweed fertilizer were significantly increased by 21.97%,32.46%and 21.05%,respectively.Compared with the control group,the root activity of tomato seedlings was significantly increased by 46.26%.However,root viability under algal fertilizer+salt stress was significantly higher than that under NaCl stress,with an increase of 85.46%compared with that under salt stress.Under NaCl stress,contents of MDA,O₂^-and H₂O₂ in tomato seedling leaves were significantly higher than those in CK treatment.Compared with CK treatment,there was no significant change in MDA and O₂^-,while the content of H₂O₂ increased slightly.The contents of MDA,O₂^-and H₂O₂ in NaCl stress treatment were considerably reduced by pre-spraying seaweed fertilizer,and the release rates of MDA,O₂^-and H₂O₂ were reduced by 68.23%,25.61%and 30.01%,respectively.The content of AsA and GSH and DHA and GSSG in tomato leaves were significantly increased by seaweed fertilizer treatment.Under NaCl stress,the contents of AsA and GSH in tomato seedling leaves were significantly reduced.Compared with plants under NaCl stress,the contents of AsA and GSH in tomato leaves treated with pre-spray seaweed fertilizer were significantly increased,138.80%and 76.03%respectively,while the contents of DHA and GSSG were significantly decreased.The antioxidant enzyme activities in tomato leaves were also significantly induced by seaweed fertilizer under NaCl stress,the activities of APX,CAT,PPO and POD in tomato seedling leaves were significantly higher than those in control.Compared with NaCl stress,the activities of APX,CAT,PPO and POD under algal fertilizer+salt stress increased by 73.48%,36.31%,126.24%and 63.32%,respectively.In conclusion,the application of seaweed fertilizer on tomato can significantly promote the antioxidant enzyme activity of tomato plants,improve the AsA and GSH levels,reduce the content of MDA and reactive oxygen species in the root system,increase the growth and biomass accumulation,and effectively alleviate the damage caused by NaCl stress on tomato plants.