Document Type : Original Article
Authors
1
Agric.. Botany Dept., Fac. Agric., Ain Shams Univ. Egypt
2
Plant Pathol. Dept., El-Minia Univ. Egypt
Abstract
Fourteen fungal isolates were isolated from naturally infected been exhibiting typical wilt symptoms. On the basis of cultural, morphological and microscopic examinations of the isolates, they were classified into Fusarium oxysporum (seven isolates), F. solani (two isolates), Macrophomina phaseolina (two isolates), Aspergillus niger, Fusarium sp. and Mucor sp. (one isolate of each). Pathogenicity test revealed that F. oxysporum isolates were more pathogenic than other ones of Fusarium spp. and M. phaseolina, whereas Aspergillus niger and Mucor sp. proved to be non-pathogenic. Best to relatively
good growth of F. oxysporum, F. solani and M. phaseolina occurred when media contained either seaweed extract (SWE) at 2ml/l or28-homobrassinoid (HBR) at 0.004 µg/l, whereas glycinebetaine (GB) at 10mM mostly favoured fungal growth. In field experiment, foliar spraying, at 18DAS, with HBR, SWE and GB at two concentrations, reduced wilt incidence. The highest reduction of wilt incidence was showed by application of HBR, followed by SWE, whereas GB application caused the lowest effect against incidence of wilt infection. Under artificial inoculation with F. oxysporum in pot experiment, disease reduction percentages were differed according to the substance, concentration and the season of the experiment. Disease reduction significantly increased with increasing the concentration of the used compound. Bean cultivated in F. oxysporum infested soil showed significant decrease in plant parameters, contents of Chlorophyll and carotenoids, concentrations of proline and TSS compared with plants cultivated in non-infested soil, whereas the activities of catalase, peroxidase and superoxide dismutase were higher in plants cultivated in infested soil. Also, concentrations of total carbohydrates and proteins were significantly decreased in pods of plants cultivated in infested soil. Foliar application of bio-regulators HBR, SWE and GB led to increase plant growth, number of pods/plant, the content of photosynthetic pigments, proline and TSS concentrations, activities of CAT, POX and SOD in leaves of treated plants in comparison with untreated plants. So, total carbohydrates and proteins significantly increased in pods of plants cultivated in both
soil types.
Keywords
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