Isolation of root-rot fungus and biocontrol agents
M. phaseolina was isolated from the wilted and rotted mungbean plants in an infected farmer’s field in Aligarh. The infected plants were packed in sterilized polythene bags and brought to the lab. Roots showing rooting symptoms were washed under running tap water. Then, they were surface sterilized with 0.1% mercuric chloride for a minute and rinsed three times with distilled water. They were further dried on filter paper and put on solidified Potato Dextrose Agar (PDA) in a Petri plate after cutting into small pieces (1 cm). The plates were then put under incubation for 6-8 days at 25±2°C. The mycelial growth of the fungus in the plates were observed for the association of M. phaseolina with the infected roots and was further identified on the basis of cultural and morphological characters (Dhingra and Sinclair 1978). After confirming, the fungus was subcultured and maintained on PDA plates.
Out of the four biocontrol agents used in the study, two of them namely, T. virens and P. aeruginosa were isolated from the soil of farmer’s field in Aligarh and processed by serial dilution method (Waksman 1922) at a dilution of 10-4 (for fungi) and 10-6 (for bacteria). The suspension (0.3 ml) from final dilution …show more content…
20 ml suspension containing 10 g M. phaseolina colonized seeds was added in the filled pots and mixed well. After two days, sowing was done (5 treated seeds/pot), and seedlings were thinned to one plant/pot after 10 days of sowing. One pot bearing a single plant represented one replicate. All the pots were arranged in a completely randomized block design consisting of 10 treatments and 3 replications of each treatment. The pots were irrigated at regular intervals. Three pots in addition were maintained for each treatment for estimating the parameters of root