Earliness and productive efficiency in tropical black bean genotypes (Phaseolus vulgaris L.) under terminal drought

Resumen

Objective: To determine the effect of earliness on grain yield of tropical black bean genotypes under terminal drought and to select those with lower susceptibility and higher productive efficiency than the cultivar Negro Jamapa.

Design/methodology/approach: Fifteen genotypes were evaluated using a randomized complete block design with three replications in two trials: one under full irrigation and another in which irrigation was suspended at the onset of flowering. Days to physiological maturity and grain yield were quantified. Analyses of variance were performed for each moisture regime, means were compared using the Least Significant Difference test (α = 0.05), and correlation analysis was conducted. Drought response was evaluated using the drought susceptibility index (DSI) and the relative efficiency index (REI).

Results: Verdín was the earliest genotype, reaching maturity at 72.3 and 68.0 days under full irrigation and drought stress, respectively. Papaloapan/SEN 46-7-10, CIAT-103-25, Jamapa Plus/XRAV-187-3-4-4, Papaloapan/SEN 46-2-6, and Rubí exhibited the lowest susceptibility to terminal drought (DSI < 0.90), whereas Verdín, CIAT-103-25, and Jamapa Plus/XRAV-187-3-4-4 showed the highest productive efficiency (REI > 1.28), surpassing Negro Jamapa. Grain yield was negatively correlated with days to maturity under both full irrigation (r = −0.719**) and drought stress (r = −0.557*).

Study Limitations/Implications: The selected genotypes constitute elite breeding materials; multi-environment evaluation is recommended.

Findings/conclusions: Earliness, as a drought escape mechanism, contributed significantly to productive efficiency under both moisture regimes. Five genotypes with the lowest susceptibility to terminal drought were selected, of which CIAT-103-25, Jamapa Plus/XRAV-187-3-4-4, and Verdín exhibited higher productive efficiency than Negro Jamapa.