Protective effects of silicon and silicate salts against white rot disease of onion and garlic, caused by Stromatinia cepivora

Abstract

This study aimed to determine the effect of silicon and silicate salts in reducing the incidence of white rot disease, caused by Stromatinia cepivora, on onion and garlic plants. Under greenhouse conditions silicon and silicate salts was used at 0.1, 0.2 and 0.3%. Before planting, onion transplants and/or garlic cloves were dipped for 1 h in the desired concentration. After planting, stem bases of plants were supplemented with the same concentration three times intervals at 30, 60 and 90 days after planting. Data showed that successful application resulted from silicon and silicate salts was obtained at 0.3%, which significantly reduced the incidence of white rot and improved the growth of onion and garlic plants. However, there were no significant differences between some treatments at 0.1, 0.2 and/or 0.3%. Field experiments were conducted in soils naturally infested with S. cepivora for 2 years to evaluate the effect of silicon and silicate salts at 0.3% on white rot incidence as well as the mechanisms underlying the observed of disease reduction. Application of silicon and silicate salts significantly reduced the incidence of white rot disease, increased the amount of chlorophyll a, chlorophyll b, carotenoids, proline and promoted the bulbs yield of onion and garlic plants. Potassium silicate solution (Ps) and sodium meta silicate pentahydrate (Ss) were more effective treatments. Calcium silicate was the least effective treatment. Application of silicon and silicate salts resulted in the increase of soil dehydrogenase enzyme and CO2 evolution in the rhizospheric soil of onion and garlic plants. Applications of silicon and silicate salts significantly stimulated systemic defense enzymes and enhanced the expressions of some genes into proteins in onion and garlic plants. These findings suggest that silicon and silicate salts reduced the incidence of white rot disease and exerts a beneficial effect on the field-grown garlic and onion plants, providing an alternative disease management strategy.