Abstract:

【Objective】 Effects of multi-functional bacterial mixture BCL-Rs on promotion of cotton growth under salt stress and Rhizoctonia solani damping-off were studied. 【Method】 BCL-Rs were obtained by combining biocontrol bacteria complex BCL-8 with salt stress-relieving strain Klebsiella oxytoca Rs-5. The function of BCL-Rs on cotton growth was investigated in pot tests, plot experiments and field trials. 【Result】 The BCL-Rs had an obvious inhibitory activity to Rhizoctonia solani, and BCL-Rs-treated cottons showed a good performance of relieving salt stress, and significant resistance to damping-off caused by Rhizoctonia solani. Compared with the control, the control efficacy of damping-off on cotton reached up to 55.37% and 51.06% in pot and plot experiments, respectively. And the dry weight of cotton seedlings increased by 40.85% and 25.81% under the salt stress conditions, respectively. The results of cotton field trials showed that the growth of cotton seedlings was promoted by coating and drip irrigation with BCL-Rs. Physiological characters of cotton, including plant fresh weight, dry weight, plant height, and leaf area increased significantly. The production of cotton increased by 10.51% compared with the conventional treatment. 【Conclusion】Cotton damping-off caused by Rhizoctonia solani was significantly suppressed by the bacterial mixture BCL-Rs even under the salt stress conditions, indicating a synergistic effect of biocontrol bacteria BCL-8 and salt stress-relieving strain Rs-5.

Key words: cotton, multi-microbial agent, Bacillus subtilis BCL-8, Rhizoctonia solani, salt stress-relieving