Physiological traits affecting drought tolerance in Ontario-adapted soybean
Under water limited conditions, increased water use efficiency by crop plants is beneficial. Using Ontario-adapted soybean ('Glycine max' (L.) Merr.) this study examined the genetic variability for both water use efficiency and a potential surrogate trait, dark adapted leaf conductance. The genetic variability of root elongation rate under osmotic stress, a trait likely to be beneficial in drought conditions, was also measured. Significant genetic variation was found in the Ontario germplasm for all three traits. This variation provides potential for breeding more drought tolerant soybean varieties using material already adapted to Ontario. A strong correlation was found between the water use efficiency and dark adapted leaf conductance traits, so the physiological basis of that relationship was examined. Dark adapted leaf conductance was found to be highly predictive of leaf conductance and leaf internal carbon dioxide concentration in light-adapted leaves.