REPRODUCTIVE STRATEGIES IN MEDITERRANEAN ANNUAL CLOVERS - GERMINATIONAND HARDSEEDEDNESS

Clovers from 6 sites in the eastern and western Mediterranean were exa mined for germination and seed dormancy strategies. At least 2 species were collected from each site, such that 4 strategies were compared i n 14 accessions of 11 species. The first trait was initial and final h ardseededness after I summer-autumn (long-term hardseededness), the se cond was the pattern of hardseed breakdown during this period (short-t erm hardseededness), the third was the rate of germination at temperat ures ranging from 5 degrees C to 30 degrees C, and the fourth was the degree to which germination proceeded at high temperatures. Logistic c urves were used to describe short-term hardseededness and germination rates, and to calculate half-lives. The seeds of all species exhibited some form of protection against out-of-season rains. In accessions fr om the eastern Mediterranean the most common strategy was delayed brea kdown of hard seed, where most seeds remained hard until mid-to-late a utumn. This was the strategy used by Trifolium lappaceum, T. glandulif erum, T. clusii, and T. purpureum. In the western Mediterranean, the a ccessions also employed slow germination and high temperature dormancy . Examples were T. obscurum and T. clypeatum (slow germination) and T. cherleri and T. isthmocarpum (high temperature dormancy). It was clea r that no single germination-regulating mechanism applied to genotypes collected from any I site. However, individual species growing at dif ferent sites tended to exhibit the same strategies. The results suppor ted the idea of substitutability in reproductive traits, developed by ecological modellers. The efficacy of the 60 degrees/15 degrees C alte rnating temperature oven in predicting loss of hardseededness by the c lovers in the field was poor except for T. cherleri. The alternating t emperature ovens, which are used to predict hardseed breakdown of subt erranean clover, are unsatisfactory for most other clovers.