PHENOTYPIC SCREENING OF 32 WEST AFRICAN SORGHUM GENOTYPES FOR DROUGHT TOLERANCE

This study evaluated the agro-physiological responses of 32 sorghum genotypes subjected to water stress applied at the critical stage of transition to panicle initiation. The objective was to identify sorghum adaptation mechanisms under such stress and to determine potentially tolerant genotypes. Analysis of physiological and agro-morphological traits revealed significant inter-genotypic variability. Under stress, leaf water potential decreased from 0.59 to 4.84 MPa, indicating differentiated tolerance levels. Genotypes V1, V2, V12, V16, V22, and V28 maintained good water status and exhibited the lowest rates of leaf desiccation after stress.Stress also induced reductions in stomatal conductance (25%), photosynthesis (13%), and transpiration (40%), reflecting adaptive strategies in the genotypes. However, a marked decrease in grain yield (47%) was observed, underscoring the limits of adaptive mechanisms to sustain productivity. Combined analysis of tolerance indices (SSI, STI) and agro-physiological traits identified genotype V26 as elite, combining low stress sensitivity with high yield. Other tolerant but less productive genotypes (V2, V6, V10, V11, V12, V14, V16, V18, V24, V30, V32) may serve as gene reservoirs for breeding improvement. In addition, principal component analysis distinguished three groups of genotypes according to their adaptive profiles.These findings highlight the relevance of an integrated approach combining agro-physiological traits, tolerance indices (SSI, STI), and multivariate analyses for the selection of genotypes adapted to water stress conditions.