Effectiveness of B. pumilus in the pot trials in greenhouse conditions In vivo bacterial inoculation of tomato plants with two biocontrol agents caused a significant reduction in disease index. The efficacy of disease control was promoted following B. pumilus application in comparison to untreated plants (Table 2). The antagonistic bacteria caused less yellowish foliage and low disease severity and also enhanced different growth parameters of tomato over untreated controls. The data were subjected to analysis of variance (ANOVA) with their mean values of four replicates in which treatments were compared using least significant differences at 5% probability (p ≤ 0.05). Under pot culture conditions, ToIrMA and ToIrFT isolates stimulated shoot, root growth and dry matters considerably (Table 3). Statistical analysis of data revealed, the increase in root length was recorded 60 and 45.6% upon inoculations with ToIrMA and ToIrFT, respectively. Similarly, 84 and 78.5% increase in shoot length were observed following application of ToIrMA and ToIrFT over control treatment. Bacterial IAA production positively correlated with shoot length (r = 0.865; p ≤ 0.05). In pot trials, significant increase in shoot fresh weight was noted with ToIrMA (39%) and ToIrFT (58%) over uninoculated treatment.
Discussion Beneficial bacteria, that can cater different needs of growing plant, act as a consortium along with other micro-organisms in the rhizosphere. Understanding the interaction between microbial inoculants and plant systems will pave way to harness more benefits
from microbial populations for improving plant growth and reducing plant disease (Raja et al. 2006). Some properties of Bacillus spp. including phytohormone production, induction of resistance in plants, stimulation of plant growth, considerable root colonisation and formation of desiccation-resistant spores offer good opportunity to use these traits in disease control and promoting crop yield (Siddiqui & Mahmood 1999; Siddiqui 2006).