Effects Of Saline And Alkali Tolerant Lactic Acid Bacteria On The Growth Of Wheat And Rice Seedlings

In this study,10 strains of saline-alkali-tolerant lactic acid bacteria were used to promote the early growth of wheat and rice,and to study the effects of these lactic acid bacteria on the activities of urease,sucrase and phosphatase in soil.Screening of excellent lactic acid bacteria strains which can promote the growth of wheat and rice.And through the preliminary study on the early growth of wheat and rice promoted by the selected strains in saline-alkali soil,the possibility of lactic acid bacteria to wheat and rice growth promoting bacteria(PGPB)was discussed.All 10 strains of lactic acid bacteria could grow under the condition of pH10and 8%salt concentration,showing strong salt and alkali resistance.Except for strain qz201,other strains were able to grow at 12%high salt concentration,and strains F4-14 and strain F19-30 were able to grow even at 16%salt concentration,showing superior high salt tolerance.All the 10 tested strains could produce indole acetic acid(IAA),which indicated that they had the potential to act as PGPB strain.The strains N-1,N-19,F4-14,F9-10 and F19-30 have the ability to hydrolyze proteins into amino acids for plant absorption and utilization.Pot experiments were carried out with three concentration gradients of lactic acid bacteria suspension 10~9 cfu/mL,10~8 cfu/mL and 10~7 cfu/mL.The comprehensive effect of strain N-1 on promoting the growth of wheat seedlings was the best when the irrigation concentration was 10~9cfu/mL.It could extremely significant increase the germination percentage,chlorophyll,POD activity and reduced glutathion content of wheat seedlings,and significantly increase leaf fresh weight,seedling length,SOD and CAT activities,but there was no significant change in soluble protein content.It can also increase the activity of acid phosphatase and sucrase in wheat rhizosphere soil.When the soaking concentration of strain N-1 was 10~7cfu/mL,the other values were significantly higher than those of the control,and the seedling length,SPAD value,SOD and POD activities were extremely significant higher than those of the control,except for the reduced glutathione and soluble protein contents.Strain F4-14 had the best comprehensive effect on promoting the growth of rice seedlings when the irrigation concentration was 10~8cfu/mL.It could extremely significant increase the fresh weight,seedling length,chlorophyll,SOD,POD and CAT activities of rice seedlings,and significantly increase the germination rate and reduced glutathion content.It also increases urease,acid phosphatase and sucrase activities in rice rhizosphere soil.When the soaking concentration of strain F4-14was 10~9cfu/mL,except for SPAD value,POD activity and soluble protein content,the other values were significantly higher than those of the control,and the seedling length,SOD and CAT activities were extremely significant higher than those of the control.After cultivating strain N-1 with a suspension concentration of 10~9 cfu/mL,the germination rate,leaf fresh weight and seedling length of wheat seeds were mostly higher in the range of soil salt concentration of 0%-2%and pH 7.1-8.5.However,when the soil pH was 8.0,the germination rate was slightly lower than that of the control.After soaking the strain N-1 with a concentration of 10~9 cfu/mL,the germination rate,leaf fresh weight and seedling length of wheat seeds were higher than those of the control when the soil salt concentration was 0%-2%and the pH was 7.1,7.3 and 8.5.Except when the soil pH was 7.5,the seedling length was higher than the control,and other values were slightly lower than the control.When the soil salt concentration was 0%-2%and the pH was 7.1-8.5,the concentration of the suspension was 10~8 cfu/mL of the strain F4-14,and the germination rate of the rice seeds was higher than that of the control.This study showed that strains N-1 and F4-14 can promote the growth of wheat and rice seedlings,improve soil quality,increase the germination rate of crops in saline-alkali soils,and have potential as bio-fertilizers or PGPB strains for agricultural applications.