Growth and water relations of diverse populations of Lolium perenne exposed to drought in field, glasshouse and controlled environment

Nineteen populations of Lolium perenne were grown near Aberystwyth as small plots (sown in 1988) in the field, and as pot plants (sown in 1989) in the glasshouse and controlled environment (CE). In the summer of 1989 they were subjected to drought, and then rewatered. Herbage growth and water relations characters were measured. There was significant diversity between populations (narrow-sense heritability) for: herbage production and yield stability before, during and after drought; tillering; osmotic potential and adjustment; tissue water content; and membrane stability (MS) following heat shock. There were no such differences in leaf water conductance, MS following desiccation shock, or chlorophyll stability under osmotic stress. The range of expression of characters was very different in the three environments, as was the ranking of populations, emphasising the danger of working in unnatural environments. Correlation analysis revealed no relationships between growth and physiological characters that were consistent across environments. Nevertheless, hierarchical cluster analysis indicated that some populations having a 'hay-type' morphology performed well over all three environments, and merit further study.