Vernalization and Photoperiod Requirements for Maximum Flowering of Cicer Milkvetch1

Cicer milkvetch (Astragalus cicer L.) does not flower in artificial environments that are used to induce flowering of the more commonly grown forage legumes. Therefore, the objectives of this study were to determine the vernalization and photoperiodic requirements of cicer milkvetch and to develop a practical chilling treatment for subsequent flowering in a greenhouse environment. When field grown plants of the cultivar ‘Lutana’ were brought to the greenhouse every 2 weeks from mid‐September through December, percent of plants flowering increased linearly from 29 to 100. Removal of top growth in mid‐September reduced subsequent flowering from 75 to 33%. Flowering after vernalization at 5 C night/20 C day (5/20 C) the laboratory was better than after vernalization in the field except for the late November and early December sampling dates. Percentge of plants flowering (95 to 100%) and profuseness of flowering (12 to racemes/plant) were similar [or the 5/20 C laboratory treatment and the late field sampling dates. The 5/20 C treatments were 6 weeks in duration with a total of 364 hours at 5 C. Considerable variability exists among vernalized plants of the cultivar Lutana for photoperiodic response to flowering. Although only 30% of the plants flowered at the 13‐hour photoperiod, a few plants flowered profusely. The highest percentage of plants flowering (98%) and the most profuse flowering (13.3 racemes/plant) occurred at photoperiods of 15 and 16 hours.