Screening And Identification Of Saline-alkali-tolerant Growth-promoting Bacteria In Songnen Plain And Research On Its Plant Growth-promoting Effect

Songnen Plain,the largest part of Northeast China Plain,has a large area of saline-alkali land and is more heavily salinized.The saline-alkali soil in this region is rich in saline-alkali-tolerant microorganisms,and some of them have unique growth-promoting function,which can be used as beneficial strains to promote better and faster growth of crops.In this study,salt-alkaline soil samples were collected from Songnen Plain area,and the growth-promoting strains with the functions of dissolved organic phosphorus,dissolved inorganic phosphorus,ferruginous carrier and IAA were screened,the specific yield of related growth-promoting indexes was determined,and the excellent strains were selected as fungicides and applied to sorghum seeds to explore the effect on germination rate,germination potential,bud length and root length of sorghum.The results of this study are as follows:(1)Twelve strains of growth-promoting bacteria were isolated from the saline-alkaline soil of Northeast Songnen Plain,through morphological and physiological and biochemical characteristics,it was preliminarily determined that these bacteria belong to Bacillus.(2)Through salt tolerance analysis,it was found that 12 strains could grow on 1-3% salt medium,and 1-2,X-3,Lirui(2)could grow on 6% salt medium;through the analysis of alkali resistance,it was found that 12 strains could grow on the medium with p H 7-10,and 1-2,X-3,Lirui(2)and BA-1 could grow normally on the medium with p H 12;through the determination of the growth curve,the optimum growth salt concentration of all strains was found to be between 1-3%.It is proved that these strains have strong salt-alkali resistance and strong environmental adaptability.(3)By qualitative determination,12 strains of these 12 strains were found to be capable of dissolving organic phosphorus,there were 9 strains with the function of dissolving inorganic phosphorus,12 strains with the function of producing IAA,8 strains with the function of producing iron carrier,at the same time,there were 8 strains which could dissolve organic phosphorus,dissolve inorganic phosphorus,produce iron carrier and produce IAA.(4)Through quantitative determination,it was found that the ability of 12 strains to dissolve organic phosphorus ranged from 1.82 mg/L to 14.08 mg/L,of which strain 1-2 was the best,and the ability of 9 strains to dissolve inorganic phosphorus ranged from 10.42 mg/L to 33.73 mg/L,among which strain X-3 was the best,the IAA production ability of 12 strains ranged from 4.31 mg/L to 30.52mg/L,among which strain M-12 had the strongest ability,and the ability of 8strains to produce siderophore ranged from 28.76% to 45.85%,among which strain L-3 had the strongest ability.(5)The germination test of sorghum seeds was carried out by using four excellent functional strains obtained from screening.It was found that the germination rate,germination potential,root length and bud length of sorghum seeds after soaking were higher than those of the control group without soaking,The most effective was strain 1-2,its Germination rate was higher than control23.33%,germination potential was higher than control 23.34%,root length was higher than control 2.13 cm,bud length was higher than control 1.86 cm.