Responses of cassava varieties to harvest timing under rainfed conditions in the Agreste region of Alagoas, Brazil
ABSTRACT This study evaluated the growth, ecophysiological performance, and yield of cassava varieties as affected by harvest timing under rainfed conditions in the Agreste region of Alagoas, Brazil. The experiment was conducted from April 2023 to December 2024, using a 2 × 5 factorial scheme in a randomized block design with four replicates. Two cassava varieties (Caravela and Pretinha) were assessed at five harvest times (12, 14, 16, 18, and 20 months after planting), with agrometeorological, growth, physiological, and yield variables monitored throughout the cycle. Although the regional climate, characterized by adequate annual rainfall and mean air temperature, was generally favorable for cassava cultivation, summer droughts limited vegetative growth. The Pretinha variety showed greater shoot dry biomass accumulation, reaching 51.4 t ha-1 at 20 months after planting (MAP). By contrast, Caravela exhibited superior root performance, achieving higher fresh root yield (61.5 t ha-1), dry root yield (34.6 t ha-1), starch yield (18.7 t ha-1), and harvest index (0.7). Physiological evaluations revealed significant cassava plasticity in response to seasonal water deficit, with coordinated adjustments in photosynthesis, stomatal conductance, and transpiration across harvest times. Overall, Caravela is more suitable for industrial purposes, whereas Pretinha is better adapted to production systems that require high shoot biomass.