Effect of silicon fertilization on the tolerance of Castanea sativa Mill. seedlings against Cryphonectria parasitica Barr.

Chestnut is an important crop in Portugal, representing an important source of revenue for mountain regions in this country. However, it has been strongly affected by the chestnut blight, a severe disease with negative consequences to fruit production, since there is still no definitive solution to this problem. Silicon is considered a nutrient for agricultural crops by conferring resistance to plants under biotic stress conditions through the combination of a physical and chemical defense system to fight against pathological fungi which attack leaves, roots and stems. Based on these factors, this study evaluates the influence of SiK® on chestnut plants infected with Cryphonectria parasitica. Three concentrations were studied: 5 mM, 7.5 mM and 10 mM SiK®. Results showed that Si fertilization can reduce the disease severity and the mortality rate of chestnut plants. The supply of 7.5 and 10 mM SiK® on PDA petri plates resulted in a total capacity of suppression (100% PI) of C. parasitica mycelium growth as opposed to the control petri plates (PDA). These concentrations also increased the antioxidant enzyme activity, catalase (CAT) and superoxide dismutase (SOD) measured 60 days after the inoculation with the fungus. In addition, the SiK® application increased the total phenolic compounds and soluble proteins content, which occurred over time. Also, increasing concentrations of SiK® increased the tolerance of seedlings to C. parasitica. The present study indicates that Si fertilization may be used in the future as a control method against chestnut blight.