Effects of Commercial and Indigenous Microorganisms on Fusarium Wilt Development in Chickpea1

Abstract

The purpose of this research was to determine whether Bacillus subtilis, nonpathogenic Fusarium oxysporum, and/or Trichoderma harzianum, applied alone or in combination to chickpea (Cicer arietinum L.) cultivars ‘ICCV 4’ and ‘PV 61’ differing in their levels of resistance to Fusarium wilt, could effectively suppress disease caused by the highly virulent race 5 of Fusarium oxysporum f. sp. ciceris. Seeds of both cultivars were sown in soil amended with the three microbial antagonists, alone or in combination, and 7 days later seedlings were transplanted into soil infested with the pathogen. All three antagonistic microorganisms effectively colonized the roots of both chickpea cultivars, whether alone or in combination, and significantly suppressed Fusarium wilt development. In comparison with the control, the incubation period for the disease was delayed on average about 3 days and the final disease severity index and standardized area under the disease progress curve were reduced significantly between 14 and 33% and 16 and 42%, respectively, by all three microbial antagonists. Final disease incidence only was reduced by B. subtilis (18‐25%) or nonpathogenic F. oxysporum (18%). The extent of disease suppression was higher and more consistent in ‘PV 61’ than in ‘ICCV 4’ whether colonized by B. subtilis, nonpathogenic F. oxysporum, or T. harzianum. The combination of B. subtilis 1 T. harzianum was effective in suppressing Fusarium wilt development but it did not differ significantly from treatments with either of these antagonists alone. In contrast, the combination of B. subtilis 1 nonpathogenic F. oxysporum treatment was not effective but either antagonist alone significantly reduced disease development. r 1998 Academic Press