EFFECTS OF POTASSIUM SILICATE FOLIAR APPLICATION ON PLANT VIGOR AND POWDERY MILDEW DISEASE REDUCTION OF GRAPEVINE CV. BEAUTY SEEDLESS

Abstract

Climatic and pest factors are the major causes of yield loss of grape in Thailand. Nowadays, silicon (Si) is extensively used as a beneficial element for enhancing vigor of cereal plants. However, the role of Si in enhancing vigorous of grape is scant. The objective of this study was to evaluate the effect of potassium silicate (K₂SiO₃) on plant vigor and reduction of powdery mildew disease of grape. The experiment was laid out in Randomized complete block design (RCBD) with 4 replications. Four concentrations of potassium silicate (0, 1000, 2000 and 3000 mg/L/plant) were foliar applied to the grapevine cv. Beauty Seedless at full bloom-setting growth stage. Thereafter the foliar application was repeated every 10 days for 7 times. Then, growth, yield, index of berry crack and disease index of powdery mildew of leaf and berry were determined in 200 sub-samples for each treatment. The results revealed that potassium silicate at the concentration of 1000 mg/L decreased berry crack index and powdery mildew disease index in leaf and berry for 27.50, 30.65 and 34.65% respectively. The concentration of 2000 and 3000 mg/L showed the greatest decrease of berry crack index and powdery mildew disease index in leaf and berry for 92.56, 79.03 and 70.83% respectively, which were significantly higher than the concentration of 1000 mg/L. Moreover, leaf chlorophyll content and yield of grape were slightly increased by potassium silicate application. Thus, we can conclude that potassium silicate has an important role in enhancing plant tissues vigor against berry cracks and plant pathogen infection rather than promoting growth and yield of grape.