Abstract:

The research on the plant growth promoting rhizobacteria of salt tolerant plants is helpful to improve the saline alkali soil with rhizosphere growth promoting bacteria. In this study, we determined the growth promoting characteristics of the 110 bacterial strains isolated from the rhizosphere soil of salt tolerant plants in the north of Yinchuan, Ningxia, including phosphate solubilization, IAA production, ACC deaminase production and siderophores production. Through the interaction of strains, 11 strains were screened for identification and construction of compound bacteria group, and the growth promoting effect of group C3 and C8 on plant seedlings was verified by pot experiment. The results showed that the growth promoting ability of different strains was quite different. Among them, 23 strains could dissolve inorganic phosphorus, and the available phosphorus content ranged from 2.90 mg∙L^-1 to 70.92 mg∙L^-1. 6 strains could produce ACC deaminase, and the highest enzyme activity was 1.56 μmol∙mg^-1∙h^-1. 46 strains had IAA production capacity, IAA production was 1.33-34.74 mg∙L^-1. 24 strains could produce siderophores. 11 highly active strains were screened, which belonged to Bacillus, Pseudomonas and Sphingomonas, respectively. A total of 9 compound bacteria group were constructed. Among them, the activity of ACC deaminase in C8 was the highest (3.67 μmol∙ mg^-1∙h^-1), followed by C3 (2.77 μmol∙mg^-1∙h^-1). The available phosphorus content and IAA production were 4.62-13.30 mg∙L^-1 and 3.52-56.96 mg∙L^-1, respectively, which were the highest in group C3. Group C1-C4 has stronger ability to produce siderophores than others. Pot experiments showed that inoculating C3 and C8 could significantly increase the biomass of Medicago sativa and Panicum virgatum seedlings. The growth promoting effect of C3 was especially significant. Compared with the control, inoculating with C3 could increase the plant height, aboveground fresh mass/dry mass of alfalfa and switchgrass seedlings by 54.93%, 50.96%, 113.8%/119.6% and 124.6%/82.08%, respectively. Group C3 has the potential to be developed into microbial fertilizer.

Key words: salt tolerant plants, plant growth-promoting rhizobacteria, growth promoting activity, strain identification, construction of compound bacteria, growth-promoting effect

摘要：

开展盐渍化土壤中耐盐植物根际促生菌研究,有助于利用根际促生菌改良盐碱土壤。以前期分离自宁夏银北盐碱区耐盐植物根际土壤的110株细菌为材料,测定了菌株解磷、产IAA、产ACC脱氨酶和铁载体等促生特性,通过高活性菌株的交互作用,筛选出11个互不拮抗的菌株进行了菌种鉴定和复合菌群的构建,并验证了高效菌群C3和C8对植物幼苗的促生效果。结果表明：不同菌株的促生能力差别较大,其中23株细菌能够溶解无机磷,解磷量在2.90—70.92 mg∙L^-1之间;6株能够产生ACC脱氨酶,酶活性最高为1.56 μmol∙mg^-1∙h^-1;46株菌具有产IAA的能力,IAA产量在1.33—34.74 mg∙L^-1之间;24株菌能够产生铁载体。筛选出的11个高活性菌株分别隶属于芽孢杆菌属、假单胞菌属和鞘氨醇杆菌属,每4个菌株为组合共构建出9组复合菌群,其中C8组合ACC脱氨酶活性最高,达到3.67 μmol∙mg^-1∙h^-1;其次是C3组合,为2.77 μmol∙mg^-1∙h^-1;产生的IAA和解磷量分别在4.62—13.30 mg∙L^-1和3.52—56.96 mg∙L^-1之间,均为C3组合最高;产铁载体能力表现为C1—C4组合较强。盆栽实验表明,接种复合菌群C3和C8能明显促进苜蓿和柳枝稷幼苗生物量的增长。C3的促生效果尤为显著,与对照相比,使苜蓿和柳枝稷幼苗的株高分别增长54.93%和50.96%,地上鲜质量/干质量分别增加113.8%/119.6%和124.6%/82.08%,具备开发为微生物菌剂的潜能。

关键词: 耐盐植物, 根际促生菌, 促生活性, 菌种鉴定, 菌群构建, 促生效应