Induction of Systemic Resistance in faba bean Against chocolate spot Diseases severity Using Chemical Inducers under Field Conditions

摘要

Chocolate spot caused by Botrytis fabae (Sard.) is the most important disease of faba bean in Egypt. All tested concentrations of ascorbic acid had no significant inhibitory effect on tested fungus. Meanwhile, complete reduction in linear growth was obtained with potassium carbonate (KHCO3) at concentration of 20mM. The highest reduction was obtained with potassium carbonate at concentration of 10 mM and Di-potassium hydrogen phosphate (K2HPO4) at 20 mM which reduced the linear growth by 76.8 and 82.6%, respectively. Under field conditions, the highest reduction in disease severity was obtained with KHCO3 and K2HPO4 at concentration of 20 mM and the fungicide Redomil-plus which reduced the chocolate spot disease severity by 74.2, 71.2 and 72.7% during two successive growing seasons, respectively. Treated faba bean plants with KHCO3 and K2HPO4 at concentration of 10mM resulted in reducing the disease severity by 57.5 and 54.5%, respectively. As for faba bean yield the highest increase was obtained with KHCO3 and K2HPO4 at concentration of 20 mM which recorded as 65.5 and 58.6% during the two successive growing seasons, respectively. Treated faba bean plants with KHCO3 and K2HPO4 at concentration of 10mM and the fungicide (Redomil–plus at 2g/L) resulted in increasing the faba bean yield by 49.1, 41.3 and 42.2%, respectively. All concentrations of chemical inducers significantly increased the chitinase activity. The highest increase in chitinase activity was obtained with KHCO3, and K2HPO4 and ascorbic acid at concentration of 20mM which recorded as 112.5 and 118.8 and 106.3%, respectively. The obtained results in the present study appears that an urgent investigation of possible alternatives, environmentally safe, bioactive natural products are able to control such diseases is possible.