Variation in growth of overwintered stolons of contrasting white clover populations in response to temperature, photoperiod and spring environment

The response of overwintered stolons of nine contrasting white clover populations to temperature, photoperiod and natural conditions was studied in six environments during the spring. Rate of leaf appearance, leaflet length, petiole length, stolon internode length, dry matter distribution within the plant and total dry weight were measured on 15 plants of each population/environment combination. Most characters, except leaf size and proportion of dry matter allocated to leaf, responded positively to temperature in the range 10 – 20°C. A positive effect of photoperiod extension was also found for all characters except rate of leaf appearance, internode length and distribution of dry matter to leaf. Population differences in response to environment were found which were related to both leaf size classification and origin. Stolon dry weight was positively correlated with leaf length, petiole length and stolon internode length in most environments. The relationships between the eight characters were often complex and canonical variate analysis provided a convenient way to discriminate between the populations based on all eight characters.