The physiological response to moisture supply of cyanogenic and acyanogenic phenotypes of trifolium repens l. And lotus corniculatus l.

Abstract

When grown in moist or droughted conditions the cyanogenic and acyanogenic phenotypes of L. corniculatus and T. repens germinated with equal frequency, and produced similar vegetative yields and possessed equal sexual vigour. There was no significant difference in mortality between the phenotypes of L. corniculatus when severely desiccated but there was a delay in stomatal closure by the cyanogenic form. The leaf tissue of the cyanogenic phenotype of T. repens was less adept at preventing water loss when subjected to negative water potentials but there was no difference between the rate of transpiration of the phenotypes of this species. This was confirmed by the equal number of fatalities of the phenotypes when severely desiccated. Selection by drought against the cyanogenic phenotype of the two species appears to be due either to linkage of the genes responsible for cyanogenesis with genes causing fitness responses to environmental factors, or to the fact that these alleles are acting as modifiers of the fitness genes, rather than to the release of HCN from damaged tissue of cyanogenic individuals. © 1977 Nature Publishing Group.