Effect of Magnesium on the Development of Sheath blight in Rice

This study investigated the effect of magnesium (Mg) on sheath blight, caused by Rhizoctonia solani, development on rice plants from cultivars BR‐IRGA 409 and Labelle grown in nutrient solution containing 0.062, 0.125, 0.25 and 0.50 mm of Mg. Sheath blight progress on inoculated sheaths was evaluated by measuring lesions expansion (mm) at 24, 48, 72 and 96 h after inoculation. Data were used to calculate the area under lesion expansion progress curve (AULEPC). The relationship between the foliar Mg concentration and the Mg rates was quadratic. The Mg concentration on leaf sheaths tissue was highest at the Mg rates of 0.389 and 0.400 mm, respectively, for cultivars BR‐IRGA 409 and Labelle. A linear model best described the relationship between the AULEPC and the Mg rates. The AULEPC decreased by 48.7 and 26.2% for plants of cultivars BR‐IRGA 409 and Labelle, respectively, as the Mg rates in the nutrient solution increased. The results permitted to conclude that high foliar Mg concentration played a pivotal role to decrease sheath blight lesions expansion.