| Improving saline-alkali soil,expanding the area of cultivated land and improving the ecological environment are urgent problems to be solved at present.Plant rhizosphere growth-promoting bacteria(PGPR)are widely used in microbial fertilizers,which can enhance crop stress resistance,promote plant growth and development and improve soil environment.In this study,the strains preserved in the laboratory were used as materials to screen the strains with growth-promoting function and saline-alkali tolerance,and the pot experiments were carried out to verify the growth-promoting effect of the strains with good performance on eggplant under normal conditions and saline-alkali stress conditions.Through the detection of the functional indexes of potassium,proteolytic,indoleacetic acid production and saline-alkali tolerance of the original strain,as well as the effect of primary screening strain on seed germination rate and seedling growth of pakchoi under saline-alkali stress,four strains with the most significant effects of BOB-1,ZSB-2,MIB-31 and MIB-40 were selected and identified.The results showed that BOB-1 was identified as Bacillus velezensis,ZSB-2 as Bacillus megaterium,MIB-31 and MIB-40 were all Bacillus paralicheniformis.Eggplant was used as a pot experimental crop to verify the growth-promoting effect of four kinds of growth-promoting bacteria BOB-1,ZSB-2,MIB-31 and MIB-40 on eggplant under normal conditions.The results showed that BOB-1,ZSB-2,MIB-31 and MIB-40 could significantly increase the plant biomass of eggplant,and the plant height,stem diameter,fresh weight and dry weight of BOB-1 were 20.39%,22.88%,65.50% and 57.86% higher than that of CK,respectively.The content of photosynthetic pigments in eggplant leaves was also significantly higher than that of CK,of which BOB-1 increased the most significantly,and the contents of chlorophyll a,chlorophyll b,total chlorophyll and carotenoids increased by 49.57%,33.39%,44.73% and 47.73% respectively compared with the control.The activities of peroxidase(POD),superoxide dismutase(SOD)and catalase(CAT)in eggplant roots were significantly higher than those of CK,and the most significant increase of MIB-40 was 46.45%,158.47% and 94.72%,respectively.Malondialdehyde(MDA)in eggplant roots was significantly lower than that of CK,and the most significant reduction effect of BOB-1was 35.08%.Compared with the control,the activities of urease,catalase,sucrase and phosphatase in the rhizosphere soil of eggplant also increased in varying degrees.The results showed that BOB-1,ZSB-2,MIB-31 and MIB-40 could promote the growth of eggplant by increasing root activity,soil enzyme activity and photosynthetic pigment accumulation in leaves.Eggplant was used as a pot experimental crop to verify the growth-promoting effect of four kinds of salt-tolerant growth-promoting bacteria BOB-1,ZSB-2,MIB-31 and MIB-40 on eggplant under saline-alkali stress.The results showed that BOB-1,ZSB-2,MIB-31 and MIB-40 could significantly increase the plant biomass of eggplant under saline-alkali stress,and ZSB-2 had the most significant effect compared with CK1.The plant height,stem diameter,fresh weight and dry weight increased by 16.42%,40.49%,167.1% and 105.18%,respectively.The photosynthetic pigment content of eggplant leaves was significantly higher than that of CK1,and the most significant increase of chlorophyll a,total chlorophyll and carotenoid content of MIB-31 was 12.91%,15.56% and 13.90% respectively.The most significant increase of chlorophyll b was 43.03%.Compared with CK1,soluble sugar,reducing sugar,proline and soluble protein in eggplant leaves also increased significantly(P< 0.05).Among them,the highest increase in soluble sugar and reducing sugar in BOB-1 was48.62% and 91.71%,respectively,and the most significant increase in proline and soluble protein was 83.16% and 49.27%,respectively.The activities of peroxidase(POD),superoxide dismutase(SOD)and catalase(CAT)in eggplant roots were significantly higher than those of CK1,and the most significant increase of ZSB-2 was 91.88%,125.25% and 65.97%,respectively.The contents of malondialdehyde(MDA)and superoxide anion free radicals in roots were significantly lower than those in CK1,and the most significant decrease in superoxide anion free radicals in BOB-1 was 52.81%.Compared with the control,urease,catalase,sucrase and phosphatase in the rhizosphere soil of eggplant also increased in varying degrees.The contents of vitamin P and anthocyanin in eggplant fruits increased significantly compared with CK1,and the highest increases in vitamin P and anthocyanin contents in MIB-40 were 86.53% and 129.35%,respectively.At the same time,the study on the composition spectrum of flora diversity showed that salt-tolerant growth-promoting bacteria fertilizer had an effect on the α-diversity and β-diversity of eggplant soil community under saline-alkali stress,which significantly changed the richness and diversity of microbial community.This shows that under saline-alkali stress,BOB-1,ZSB-2,MIB-31 and MIB-40 can increase the osmotic substance content of eggplant,maintain the balance of cell water osmotic pressure,keep the membrane structure intact,improve soil fertility,change the structure of microbial community in soil,promote the absorption of nutrients by eggplant,and alleviate the growth pressure of eggplant under stress.So as to promote the growth of eggplant and improve the fruit quality of eggplant. |
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