Can cellular osmolarity be used as a predictor for drought tolerance in common bean?

Abstract: Common bean, Phaseolus vulgaris, is a protein and nutrient rich food source grown around the world. Rwanda has one of the highest per capita consumption rates in the world. With climate change threatening food security, the need for more adaptable crops is rising. This study aims to explore traits related to drought tolerance, in particular cellular osmolarity, to help create more drought tolerant beans in the future. Eighteen Rwandan landraces of P. vulgaris collected in the 1980’s were chosen from a seed bank in Columbia and for each 8 replicas were planted. Gas exchange measurements and a drought experiment was performed. Most varieties wilted within 5-7 days after termination of watering, and had a water content of around 15-20% at the time of wilting. Chlorophyll fluorescence did not show major differences between the drought stressed group and the control group, nor between wilted plants and vital plants. Osmolarity had only weak correlations with wilting time, percentage of field capacity left at the wilting point and conductivity. Therefore, in this study osmolarity was not a good predictor of drought tolerance. Though there are several sources of error that could have affected the result, one being a very limited amount of osmolarity measurements.