Growth potential of buds of two contrasting cultivars of white clover during winter and early spring

In order to compare the growth potential of buds of two contrasting cultivars of white clover (Trifolium repens L.) (cv. AberHerald and Grasslands Huia) during the winter-early spring period, we adapted a method to assess the potential for activity of shoot buds and root primordia. The growth potential was evaluated following the excision of individual stolen nodes sampled in the field, from experimental plots located in the eastern part of France. Two populations of nodes were sampled: (i) the youngest node emerged from the apical bud (node i), (ii) the third node behind the apex (node 3). The excised nodes were placed in controlled conditions and the outgrowth of axillary buds and roots was recorded every day for a week. The study demonstrated a seasonal influence on the potential for activity of axillary buds and root primordia, particularly for buds at node 3. The proportion of potentially active shoot and root buds was less than 50 % at the end of March, and then increased from end of March to reach 80 % in April. The data indicated a genetic variation in potential for outgrowth during winter. AberHerald had a higher percentage of potentially active buds than Huia during winter, irrespective of the node position. Moreover AberHerald buds had faster rates of outgrowth than Huia buds. Differences between cultivars in winter survival and potential for growth in spring were linked to identified cultivars' differences in developmental characteristics of buds.