INFLUENCE OF ZINC, COPPER AND MANGANESE ON DRY MATTER YIELD AND PHYSIOLOGICAL TRAITS OF THREE CASSAVA GENOTYPES GROWN ON SOIL MICRONUTRIENT DEFICIENCIES

Deficiencies of one or more micronutrients is a common cause of low yield in cassava. The aims of this research were investigated the effects of foliar applications of zinc, manganese and copper on cassava plant growth in soils where these micronutrients are often limiting. Three cassava genotypes (Kasetsart 50, Rayong 9 and CMR 38-125-77) were treated with foliar fertilizer applications varying in Zinc, Copper and Manganese. SPAD chlorophyll meter readings, visual ratings of plant nutrient deficiencies, leaf area, harvest index, and plant height significantly improved as a result of the micronutrient foliar applications. Shoot, tuber and total biomass dry weights were also improved by the foliar sprays. Foliar spray of 2% ZnSO4 center dot 7H(2)O increased biomass yield in all cassava genotypes by 30.6% to 75.7% compared to application of soil fertilizers alone. The information from this study is now being used to develop appropriate management guidelines for cassava production under micronutrient deficiencies conditions.