EVALUATING DROUGHT RESISTANCE IN GERMPLASM OF MEADOW FESCUE

The drought resistance of 25 accessions of meadow fescue (Festuca prat ensis Huds.) from seven countries was investigated in four experiments : two in the glasshouse using pot-grown plants from which water was wi thheld for various periods, and two in controlled environments under o smotic stress. There were significant differences between populations ('broad-sense heritabilities' or 'repeatabilities') in all four experi ments. In the glasshouse there was a large residual effect of yield po tential on production during and after slight-to-moderate drought, and different susceptibilities appeared only after very severe drought. T he most consistently high-yielding accessions were from the Bergamo al ps in Italy. Recovery after drought was strongly correlated with tille r survival. Continued production under moderate drought was considered important in wetter climates, whereas survival and recovery under sev ere drought was often associated with low production or flowering in t he seeding year, and more typical of summer-drought climates. Leaf gro wth rates of plants subjected to zero or moderate osmotic stress were correlated with yields of irrigated or moderately-stressed plants in t he glasshouse, although there was no differential susceptibility to mi ld stress. Under severe osmotic stress there were very large differenc es in survival between populations, but there was no relationship with survival under glasshouse conditions. The inconsistency of population rankings across experiments shows that no one technique gives a full evaluation of drought resistance, and emphasizes the complex nature of the phenomenon. It was possible, however, to identify (a) regions mer iting further collections. and (b) ecotypes that had desirable respons es in all experiments and could contribute to variety improvement.