Genotypic Differences in Water Use Efficiency of Common Bean under Drought Stress

Common bean (Phaseolus vulgaris L.) is extensively grown in production zones where water is limiting. Crop water use efficiency is the ratio of biomass or seed yield produced per unit of water evapotranspired in a particular environment. Transpiration efficiency (TE) is the ratio of yield per unit of water transpired. The objectives of this study were to: (i) determine the water use efficiency (WUE) for six common bean genotypes (BAT 477, Morales, SEN 3, SEN 21, SER 16, and SER 21) in the greenhouse and for two genotypes in the field (Morales and SER 16) and (ii) determine TE for two common bean genotypes using estimated evapotranspiration rates in the field. Three greenhouse trials and two field trials were conducted during 3 yr in Puerto Rico. Three water levels in the greenhouse and two in the field were applied. Actual evapotranspiration was estimated using the generalized Penman-Monteith model based on aerodynamic and surface resistance, and with drainage type lysimeters in the field. Differences among genotypes for WUE were found in the greenhouse experiments, with SEN 3 and SER 21 showing superior WUE in several treatments. In the field, TE and WUE were affected by water level, and TE was consistent with previously reported coefficients for common bean.