Boron topdressing fertilization in sweet cassava cultivars grown in sandy soil: effects on biomass, root yield, and boron uptake and removal

ABSTRACT Boron (B) is an important micronutrient for plant root growth and development. However, its benefits for cassava crops remain unknown. We evaluated the effects of B topdressing fertilization on the root yield, biomass, and B accumulation and distribution in five sweet cassava cultivars grown in sandy soil. A randomized block design in a 5 × 3 factorial scheme with four replicates was used. The treatments included five sweet cassava cultivars (IAC 576-70, BRS 396, BRS 399, Palito, and Precoce) and three B rates (0, 1, and 2 kg·ha-1). BRS 399 and Precoce maintained stable biomass regardless of B application. IAC 576-70 increased whole plant and storage root biomass with 2 kg·ha-1 B, while the biomass of Palito decreased at this rate. Application of 1 kg·ha-1 B improved storage root biomass of the BRS 396 cultivar. BRS 399 cultivar responded positively to topdressing B fertilization; Precoce was unaffected; and 2 kg·ha-1 B was excessive in the Palito cultivar. B fertilization increased B uptake only in the Palito and IAC 576-70 cultivars, and B removal was the highest in the BRS 399 and Palito cultivars. Therefore, for soils with limited B availability, it is recommended to fertilize Palito and BRS 396 cultivars with a maximum of 1 kg·ha-1 B, and IAC 576-70 and BRS 399 cultivars with 2 kg·ha-1 B. These findings emphasize the need for cultivar-specific B fertilization to optimize cassava root production.