Growth responses of basil (Ocimum basilicum L.) to Trichoderma spp. and its influence in control and eliciting plant defense responses against Rhizoctonia solani

This experiment was designed to investigate the antagonistic effect of six isolates of two Trichoderma species, i.e. Trichoderma harzianum and Trichoderma viride on growth and eliciting plant defense responses against Rhizoctonia solani in basil (Ocimum basilicum L.). The basil seeds treated with two Trichoderma species were planted in infested soil with R. solani and plant growth and severity of damping off measurement 40 days after planting. Peroxidase activity, total phenolic and malondialdehyde compounds levels were evaluated by colorimetic assay. The results show that eed treatments with two Trichoderma species significantly increased height and dry weight of seedling shoots and root dry weight, but their effects were not significantly different on stem diameter. Two Trichoderma species significantly reduced the severity of damping off disease where the percentages disease reduced from 71.25% in infected plants to 8.75-15.75% in plants treated with fungal anthagonists. The best protection to damping off disease was obtained by T. harzianum. Trichoderma species and Rhizoctonia solani individually increased peroxidase activity and total phenolic compounds levels, but they are more pronounced in the case of applying of combination of two fungi (Trichoderma and Rhizoctonia) in comparision to the control. Experiments indicated that maximum level of total phenolic compounds is induced by T. viride. Changes in malondialdehyde concentration occurred only in infected plants without antagonists treatments. Findings indicate that the growth and defense responses of basil significantly enhanced by seed coated with a Trichoderma different species.