Induction of resistance in sesame plants against charcoal rot disease by some chemical inducers

In the present investigation sesame seeds were soaked before sowing in certain concentrations of some organic acids and mineral salts to stimulat the natural defense mechanisms in sesame plants against charcoal rot disease Macrophomma phaseolina Tassi Goid under both greenhouse and field conditions Damping off pre and post emergence and charcoal rotted plants vere decreased and percentage of healthy mature plants at maturity stage was increased by all tested chemicals comparing vith the untreated controls In this respecl applying salicylic acid SA 2 and41 butyric acid at 4tn1vf and oxalic acid at 8mM were the superior treatments for minimizing charcoal rot and maximizing healthy plants under greenhouse Meanwhile oxalic acid at 4mM salicylic acid at 2mM and nicotinic acid at 4mM proved to be the most effective treatments in field trials for decreasing charcoal rot incidence and gave the maximum yield of sesame seeds in two successive seasons 2009 and 2010 As for mineral salts using cobalt chloride CoC12 at 1 and 2mg/l and calcium chloride aCl at 8mM ere the most superior treatments for minimizing incidence of charcoal rot under greenhouse and field trials However calcium chloride CaC12 at 8mM produced the highest seed yield production in the two successive seasons 2009 and 2010 Studying some biochemical changes as markers for the induced systemic resistance indicated that considerable increases in activity of oxidative enzymes peroxidase and polyphenoloxidase phenolic compounds and sugars content were observed in root tissues of healthy sesame plants that grown from treated sesame seeds comparing with those grown from untreated seeds Generally salicylic acid SA at 2 and 4mM oxalic acid at 8mM and butyric acid at 4mM were the most effective organic acids for stimulating these defense activities Meanwhile cobalt chloride CoCI2 at 1 and 2mgl calcium chloride CaC12 at 8mM and ferrous sulphate FeSO4 at 8mM were the most effective mineral salts for stimulating natural dense in sesame plants