Differences in osmoregulation between wheat genotypes

Abstract

SEVERAL recent experiments provide evidence to support the existence of osmoregulation in plants as a means of counteracting water stresses induced by changes in the soil or evaporative environment1–3. Viewed in terms of energy potentials, decreases in the water potential, Ψ, induced by changes in the environment, are immediately offset by decreases in the osmotic potential, π, through an increase in solute content. The turgor potential, P, is thereby maintained since Ψ = π+P+τ (assuming that the matric potential, τ, is small or constant). The importance of this response is that expansion growth, which is affected directly by the turgor potential, is maintained over a range of values of Ψ2. Despite this obvious significance, little is known of the extent of this phenomenon in crop plants in general and in particular of differences between genotypes in the same or closely related species. Here we present evidence indicating substantial differences between several genotypes of wheat; in some osmoregulation was marked, whereas in others it was virtually non-existent.