The control effect of Trichoderma harzianum EMF910 on the root rot pathogens of Astragalus membranaceus in Ningxia saline-alkali regions

Abstract:

[Background] Root rot is widespread and harmful, being one of the most common diseases in the process of large-scale cultivation of Astragalus membranaceus in the northwest saline-alkali regions of China, which causes a decrease in yield and quality of A. membranaceus, and there is currently no effective control method. Trichoderma harzianum has a significant control effect on the pathogens causing root rot in rhizome crops, but its effect under saline-alkali conditions has been reported rarely. [Objective] To clarify the main pathogens causing root rot in A. membranaceus in the northwest saline-alkali areas of China, and to explore the inhibitory effect of T. harzianum EMF910 on these main pathogens under saline-alkali conditions. [Methods] The pathogens causing root rot of A. membranaceus in large-scale cultivation in the saline-alkali areas of northwest China were determined through tissue isolation, in vitro tie-back, morphological, and molecular biology methods. The inhibitory effect of T. harzianum EMF910 on these pathogens under saline-alkali conditions was studied through plate confrontation experiments. The control effect of T. harzianum EMF910 on root rot in A. astragalus in saline-alkali soil was investigated by pot experiment. [Results] The main pathogens causing root rot in A. astragalus in the northwest region were identified as Fusarium solani X12 and Fusarium obliquiseptatum P1. After culturing for 7 days under normal conditions (0% NaCl, pH natural), the plate inhibition rates of T. harzianum EMF910 on X12 and P1 reached 77.93% and 73.82%, respectively. After culturing for 7 days under saline-alkali conditions (1% NaCl, pH=8.5), the plate inhibition rates of T. harzianum EMF910 on X12 and P1 reached 70.22% and 67.95%, respectively. After culturing for 12 hours under normal conditions (0% NaCl, pH natural), the spore germination inhibition rates of T. harzianum EMF910 on X12 and P1 reached 87.21% and 86.11%, respectively. After culturing for 12 hours under saline-alkali conditions, the spore germination inhibition rates of T. harzianum EMF910 on X12 and P1 reached 72.29% and 64.47%, respectively. The pot experiments showed that in A. membranaceus pre-infected with root rot pathogens, the survival rate of A. membranaceus treated with T. harzianum EMF910 was 56.3%, while the survival rate of the control group treated with water without T. harzianum EMF910 was only 12.5%. The statistical survival rate of A. membranaceus with root rot showed that the incidence rate of root rot in T. harzianum EMF910 treatment group was 33.3%, while that in the water control group without T. harzianum EMF910 was 50.0%. [Conclusion] The main pathogens causing root rot in A. mezmbranaceus in the northwest saline-alkali areas of China are mainly F. solani and F. obliquiseptatum. T. harzianum EMF910 can effectively inhibit the growth and spore germination of these pathogens under saline-alkali conditions (1% NaCl, pH 8.5), but the inhibitory effect is lower compared to that under normal conditions (0% NaCl, pH natural). T. harzianum EMF910 has a good control effect on root rot in A. membranaceus in saline-alkali soil. These results provide data support for the biological control of root rot in A. membranaceus in saline-alkali areas of Ningxia using T. harzianum EMF910 and also provide a reference for the use of T. harzianum EMF910 to control the root rot in other saline-alkali areas of China.

Key words:Astragalus membranaceus;root rot;Trichoderma harzianum;saline-alkali condition