The effect of two biocontrol agents, namely: Trichoderma viride TM15 and Bacillus subtilis BM10, on growth, protein, free amino acids, chlorophyll, carotenoids and phenolic compounds contents, oxidative and hydrolytic enzymes activities of cucumber plants (Cucumis sativus L.) grown in soil infested with either Fusarium oxysporum f.sp. radicis cucumerinum or F. solani f.sp. cucurbitae were investigated. The results indicated that both phytopathogens caused significant decreases in plant length, fresh and dry weight of infected plants. Treatment with the tested bioagents resulted in remarkable increases in all of these growth parameters. Meanwhile, protein and free amino acids contents were increased (P = 0.05) following infections as compared to untreated control. Application of the tested bioagents rebalanced the levels of protein and free amino acids. The present results clearly established the fact that the bioagents employed not only counteract the deteriorative effect of the pathogens on chlorophyll and carotenoids, but resulted also in noticeable increments in their contents. Infection with the pathogenic Fusarium isolates induced significant increases in phenolic compounds contents, phenol oxidase, peroxidase, catalase, invertase, amylase, cellulase and carboxymethyl cellulase activities of cucumber plants as compared to those of the healthy plants. Inoculation of soil with either T. viride or B. subtilis brought about the relative magnitudes of the abovementioned physiological parameters to be comparable to those of the healthy plants.
Key words: Cucumber, Fusarium spp., Bacillus subtilis, Trichoderma viride, Protein, pigments, phenols, enzymes.
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