Variation in growth and development in natural populations of Dactylis glomerata from Norway and Portugal. I. Growth analysis.
The effects of temperature and photoperiod on the growth and development of three populations from Norway and one from Portugal were studied. Marked effects of populations, temperature, photo-period and interactions between them were found for most growth characters studied. The greatest differences in response were found between the Portuguese and Norwegian populations, although smaller differences occurred between two extreme northern Norwegian populations and a more southern population. At 5°C with 8-h photo-periods, Norwegian populations showed reduced leaf expansion and diversion of assimilates to leaf bases and roots while the Portuguese population showed continued leaf expansion. At 25°C the relative performance of the two groups was reversed.