Genotypic Differences in Leaf Water Relations between Brassica juncea and B. napus

Various kinds of measurement of tissue water status were made several times during water stress and recovery in Brassica juncea (cv Canadian Black) and B napus (cv Drakkar) Unstressed plants of the two species had similar leaf water potentials (ψw), solute (ψs) and turgor potentials (ψp) Values of relative water content (RWC) and the slope of the linear relationship between ψp and RWC (Δψp/ΔRWC) were greater in B napus than in B juncea Statistical correlations of pooled data for the watered and stressed treatments differentiated the relationships among RWC, ψw and its components in the two species The major statistical difference was that Δψp/ΔRWC was related to RWC in B napus and to ψw and ψs in B juncea A decline in Δψp/RWC with decreasing ψs in B juncea may be a mechanism for maintaining ψp at low soil water potentials through maintenance of more elastic cell walls.