Agronomic and physiological evaluation of eight cassava clones under water deficit conditions.

Cassava (Manihot esculenta Crantz) is an important crop in Africa, Asia, Latin America, and the Caribbean. This species grows adequately in drought conditions and is ideal to ensure food safety in marginal environments, such as soils with low fertility and low rainfall conditions. Complementary irrigation practices can be used, or genotypes with good yield potential can be identified against these conditions to enhance productivity in those environments. For this reason, this research aimed to study several physiological mechanisms and agronomical characteristics in eight cassava clones under prolonged water deficit. The experimental design was a split-plot where the principal plot was composed of three irrigation treatments (7, 15, and 21 days without irrigation, DWI) and the secondary plot by the eight clones. The results showed that cassava plants against drought conditions (21 DWI) decreased their growth, foliar expansion, and partially closed the stomata, avoiding water losses through transpiration. The variables of the net assimilation rate of CO2, yield, and biomass accumulation were not affected by the maximum drought period. The best clones under drought were Guajira, Guajira 3, Guajira 4, Concha Rosada, and MeVen 77-1. The frequency of irrigation 15 DWI increased the variables of gas exchange and vegetative growth. This behavior is due to the ability to tolerate complex conditions through morphological and physiological mechanisms, among them, long life leaf, stomatal control, and high photosynthetic potential.