ANNUAL COOL-SEASON LEGUMES FOR FORAGE .3. EFFECTS OF TEMPERATURE, PHOTOPERIOD, AND VERNALIZATION ON FLOWERING

Controlled-environment rooms, were used to study environmental effects on flower initiation in a range of annual forage legumes of Mediterranean origin (Trifolium, Medicago, Vicia, Lotus, Ornithopus, and Astragalus spp.). Four treatments, one strongly inductive because of high temperatures (22/16°c, day/night), long days (16 h), and vernalisation and each of the others lacking one of these favourable conditions, were used to test the importance of each factor in delaying floral initiation. Short photoperiods (8 h) delayed flowering by an average of greater than 35 days, but there was considerable variation among species in their level of response. Cool growth temperatures (16/10°c day/night) had less though more consistent delaying effect, with an average of 24 days extension of flowering time. Lack of vernalisation delayed flowering least and some species showed little or no vernalisation response. Species with a weak or negligible vernalisation requirement and a short natural period of vegetative growth could flower prematurely if planted in late summer after small-grain cereal crops. © 1979 Taylor & Fracis Group, LLC.