Low Temperature Growth in the Field of Trifolium repens Ecotypes from Northern Latitudes

Abstract

The low temperature growth of 13 ecotypes and a cultivar of T. repens was studied in the field at 2 altitudes. The results are compared with previously published data obtained in cold cabinets. One ecotype originating from 700 m above sea-level in Britain exhibited exceptional growth at both field sites. The potential importance of this ecotype is discussed. There is evidence that the ecotype partitions growth into shoot components in a different manner to that of the cultivar in autumn, a difference which subsequently affects spring growth. Two ecotypes collected from low altitudes exhibited frost injury which influenced their spring growth at the upland site. The poor performance of ecotypes originating from low altitudes when grown at altitude partly explained why only a few clinical relationships between low temperature growth and the winter temperature at the place of origin were indicated in these experiments. A hypothesis is presented suggesting that flower production of lowland types may adversely influence their potential growth in autumn. From the limited number of plants tested, it appears that ecotypes of T. repens originating from lowland areas are not well adapted to the hill environment despite their ability to exhibit good growth at low temperatures in cold cabinets.