Effectiveness of Rhizosphere Bacteria for Control of Root Rot Disease and Improving Plant Growth of Wheat (Triticum aestivum L)

摘要

Pathogenic fungus Rhizoctonia solani causes root rot disease in wheat leading to collapsing of the aerial part of the plant. To characterize antagonistic bacteria, one hundred and thirty bacterial isolates were obtained from the rhizosphere soil of wheat and these rhizobacterial isolates alongwith 72 reference strains were screened for their antagonistic interactions against R. solani under cultural conditions. Sixteen bacterial isolates inhibited the growth of R. solani and growth inhibition zone varied from 6- by different rhizobacterial isolates. Two isolates WPS3 and WPS90 caused maximum growth inhibition of the fungi. Growth inhibiton of the pathogenic fungi was also observed using culture filterates of antagonistic rhizobacterial isolates. The protein estimation of the culture filterates showed that the amount of protein excreted by different rhizobacterial isolates varied from 3.6 to 33.0 mg ml~(-1) of the supernatant. The loss of antagonistic activity after treatment with proteinase K and high temperature treatment indicated that excreted proteins are responsible for the antagonism. Pot house studies showed that inoculation of R. solani in wheat caused 85-90% root rot disease incidence at 60 to 90 days of plant growth. The single inoculation of rhizobacterial isolate WPS3 resulted in 131% increase of plant dry weight as compared to uninoculated control plants. The coinoculation of isolate WPS3 with R. solani enhanced 115% plant dry weight whereas coinoculation of Pseudomonas isolate WPS90 caused 98% increase in plant dry weight in comparison to control uninoculated plants at 90 days of plant growth. Coinoculation of Pseudomonas isolates WPS3 and WPS90 with R. solani also caused 88.9 and 66.7% disease control, respectively at 90 days of plant growth. Thus, Pseudomonas isolate WPS3 could be further exploited for plant growth improvement under field conditions.