No abstract

Efficacies of three abiotic inducers (systemic resistance agents) i.e., bion, humic acid (HA), salicylic acid (SA), compared to Rizolex-T50 as seed treatments were tested against damping-off and root rot diseases of cluster bean (Cyamopsis tetragonoloba L.) in pot and field experiments. In green house, pathogenicity test indicated that the three tested fungi were pathogenic and caused emergence damping-off. R. solani caused the highest percentage of pre-emergence damping-off. Moreover, the lowest percentage of survived plants was occurred under F. oxysporum and R. solani (26.7% for each). Rizolex-T50 presented the highest reduction in disease parameters in infested soil with the three fungi, Bion came next to the fungicide followed by humic acid then salicylic acid. All the investigated treatments significantly increased the activity of chitinase, β-1, 3-gluctronase, peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia-lyase (PAL) enzymes. As well as total content of phenolic compounds and total content of lignin were increased in cluster bean plants grown in artificially infested soil with the three tested fungi (Fusarium oxysporum, Rhizoctonia solani, and Macrophomina phaseolina) each alone compared with untreated control. In field, pre sowing seed treatments with the desired inducer of resistance inducer caused considerable increase in the photosynthesis pigments (chlorophyll-a, chlorophyll-b and total chlorophyll) and seed quality (total nitrogen and total protein). In general, the highest figured data of the increase in the cluster bean tissue were associated with the inducer resistance agents i.e., Bion, salicylic acid and humic acid, respectively, followed by seed treatment with the fungicide Rizolex-T50. Whereas the lowest increase was shown in control treatment. It could be concluded that any of bion, HA or SA can act as inducer of systemic resistance in cluster bean plant against infection by each of Fusarium oxysporum, Rhizoctonia solani, and Macrophomina phaseolina infections. Consequently, these agents could be recommended for management damping-off and root rot diseases in cluster bean plants and improving photosynthetic pigments and seed quality.

Seven different selected fungal and bacterial isolates viz., Trichoderma viride, T. harzianum, Chaetomium globosum, Bacillus subtilis, Pseudomonas fluorescens, Debaryomyces sp. and Streptomyces lavendulae and the mycorrhizal product of Glomus sp. were evaluated against the fungal pathogens, Fusarium oxysporum, Macrophomina phaseolina and Rhizoctonia solani the causal pathogens of damping-off and root-rot diseases of cluster bean in vitro, greenhouse and under field conditions. Data obtained indicated that all the tested bioagents resulted significant reduction in linear growth of the tested fungi. In this respect, in vitro. B. subtilis, P. fluorescens, T. viride, T. harzianum and C. globosum were the most effective in reducing the linear growth, whereas S. lavendulae and Debaryomyces sp. were the lowest effective. All the tested bioagents, mycorrhizae and the fungicide Rizolex-T50 significantly reduced the percentages of damping-off, root rot and wilt diseases of cluster bean when grown in artificially infested soil with F. oxysporum, M. phaseolina and R. solani under greenhouse conditions compared with control treatment. This reduction resulted in a significant increase in survived plants under soil infestation with the mixture of pathogenic fungi. Based on healthy survived plants both bacterial isolates followed by both fungal isolates were the most effective after fungicide. In-vivo, all the tested treatments, i.e., bioagents, mycorrhizae, the fungicide Rizoles-T50 showed significant decrease in the percentages of damping-off (pre-and post-emergence) and dead plants due to infection by root rot and wilt with significant increase in survived plants under the natural infection at Dakahliya governorate during two successive seasons (2016 and 2017) compared with control treatment. In case of bioagents treatments the highest seed yield plot -1 occurred under the treatment of T. harzianum followed by T. viride then P. fluorescens and B. subtilis in both seasons. From the foregoing results, it may be concluded that using T. harzianum from fungal bioagents and P. fluorescens from bacteria bioagents as seed treatments could be applied for controlling damping-off, root rot and wilt diseases in cluster bean plants and improving crop parameters and seed yield.

No abstract

No abstract