Fig. 4.

Physiological effect of drought stress on genotypic means (and standard deviation) across all three species. (A) Estimated total CO₂ assimilation, based on the area under the LiCOR curves across the entire diel cycle, for both hybrid and parental genotypes under well-watered and drought-stressed conditions. (B) Estimated total CO₂ assimilation based on the area under the LiCOR curves at night only, for both hybrid and parental genotypes under well-watered and drought-stressed conditions. (C) Leaf acid accumulation under well-watered conditions (W) vs. drought-stressed conditions (D), with genotypic mean and one standard deviation. Dashed line indicates equal values under both conditions; genotypes that fall above or below indicate that greater or lower amounts of acid, respectively, were accumulated under drought stress than under well-watered conditions. (D) Comparison of the change in night-time CO₂ assimilation induced by drought stress (x-axis) to the change in leaf acid accumulation induced by drought (y-axis). Quadrants are labelled with the phenotype observed.