关键词: 连作障碍, 拮抗, 促生, 革兰氏阴性菌, 偶氮假单胞（Pseudomonas azotoformans）

Abstract: Single colonies of culturable bacteria were isolated and purified from continuous and fallow soils of strawberry fields by the gradient dilution method, co-cultured with confrontation against Botrytis cinerea or Fusarium graminearum, and several strains of bacteria antagonistic to Botrytis cinerea or Fusarium graminearum were obtained by rescreening. The bacteria with the best antagonistic effect were subjected to determination of the fungal inhibition spectrum, evaluation of plant promotion effect and its inoculated effect on Botrytis cinerea of the strawberry. The molecular identification of it was performed. The results showed that a strain of bacteria HPS-211, which had a growth-promoting effect on tomato, was obtained. The average height and fresh weight per plant of tomato were increased by 14.5% and 26.9%, respectively, 30 d after inoculation with HPS-211. The chlorophyll content, leaf colour and glossiness of tomato were also increased. The inoculation of HPS-211 and B05.10 of strawberry seedlings showed that compared with the positive control B05.10, the inoculation of HPS-211 could reduce the gray mold index of strawberry leaves. The leaf color, plant height and gloss of the strawberry were similar to those of the inoculation of tomato. The chlorophyll and plant height of strawberry leaves in the treatment group were higher than those in the control, which reached a significant difference. HPS-211 was a kind of gram-negative bacterium with flagella, but without spores. Its molecular identification was Pseudomonas azotoformanss by 16S rDNA.

Key words: continuous cropping barrier, antagonistic, promoting growth, gram-negative bacteria, Pseudomonas azotoformans