Study On Salt-Alkali Tolerance Of Rhus Chinensis Mill. Seedlings From Different Families

With the deterioration of ecological environment,the problem of soil salinization is becoming more and more serious,which seriously restricts the development of modern agriculture.Breeding saline-alkali tolerant plants and studying the mechanism of salt-alkali tolerance are effective ways to improve saline soil.To explore the physiological response of Rhus chinensis under saline-alkali stress and select excellent families with saline-alkali tolerance,this experiment took five Rhus chinensis families T1,T2,T3,CL and M as experimental materials,and adopted the method of nutrient solution culture to simulate different concentrations of saline-alkali stress(0,50,100,150 mmol L-1 Na Cl:nahco3=1:1),and measured and analyzed the relative leaves of Rhus chinensis.The main results are as follows:(1)Under 50 mmol L^-1 saline-alkali stress,compared with the control,the leaf and root phenotypes of five families of Rhus chinensis have no obvious changes,and the leaf relative water content and root activity remain at a high level;Under the saline-alkali stress of 100?150 mmol L^-1,the phenotypic changes of Rhus chinensis in five families were observed,that is,the leaves faded and curled,the roots became discolored,rotted and decreased,and the relative water content of leaves and root activity began to decrease significantly.Among them,the phenotypic damage of T2 was the lightest,the relative water content of leaves and root activity decreased the least,followed by T1,T3 and CL,and the leaves and roots of M were most affected by stress.(2)Under different concentrations of saline-alkali stress,the photosynthesis of Rhus chinensis seedlings of five families was inhibited in different degrees,which showed as net photosynthetic rate(Pn),chlorophyll(Chl)content,potential photochemical efficiency(Fv/Fo),maximum photochemical efficiency(Fv/Fm),actual photochemical efficiency(?PSII),photochemical quenching coefficient(q P)and surface sightseeing.Furthermore,the inhibition effects of saline-alkali stress on Pn,Chl,Fv/Fo,Fv/Fm,?PSII,q P and ETR of CL and M were significantly greater than those of T1,T2 and T3.It shows that Rhus chinensis T1,T2 and T3have higher ability to resist saline-alkali stress than CL and M,and can effectively use the captured light energy to adapt to saline-alkali stress by maintaining high photochemical efficiency.(3)Under different concentrations of saline-alkali stress,the cell membrane stability of Rhus chinensis leaves of five families was damaged,which showed a significant increase in relative conductivity and MDA content,among which M's relative conductivity and MDA content increased the most,followed by T1 and CL,T2 and T3's relative conductivity and MDA accumulation were the least,and the cell membrane was relatively stable,which might be more resistant to salt and alkali.(4)With the increase of saline-alkali stress concentration,the activities of superoxide dismutase(SOD),catalase(CAT),ascorbate peroxidase(APX)and peroxidase(POD)in roots of Rhus chinensis leaves of five families increased at first and then decreased,and the POD activity in leaves kept increasing.The results showed that Rhus chinensis could effectively eliminate excess reactive oxygen species by increasing the activity of antioxidant enzymes,thus protecting photosynthetic system and maintaining high photosynthetic capacity.Among them,the activities of SOD,POD,CAT and APX in T1,T2 and T3 are significantly higher than those in CL and M,and they have stronger ability to resist oxidative stress,and may have better salt and alkali tolerance.(5)With the increase of saline-alkali stress concentration,the proline content in leaves of T1,T2 and T3 increased all the time,that in leaves of CL and M increased first and then decreased,and that in roots of Rhus chinensis from five families increased first and then decreased.Soluble protein content in leaves and roots of Rhus chinensis in 5 families increased first and then decreased;The soluble sugar content of Rhus chinensis leaves in five families has been increasing,and the soluble sugar content of roots has increased first and then decreased.It shows that Rhus chinensis can slow down the effect of stress on the normal growth of plants by increasing the content of osmotic regulators,maintaining the osmotic potential of cells,and keeping the absorption of water by cells.Among them,the contents of organic osmotic adjustment substances in T1,T2 and T3 are significantly higher than those in CL and M,which may be more salt-tolerant and alkaline-tolerant.(6)Comprehensive evaluation of salt and alkali tolerance of Rhus chinensis seedlings from five families was made by membership function calculation,correlation analysis and principal component analysis,and the order of salt and alkali tolerance was T2>T3>T1>Cl>M.