DENSITY STUDIES ON LUPINS .1. FLOWER DEVELOPMENT

In an August-sown experiment the pattern of flower development was followed for cv. Ultra (Lupinus albus L.) and cv. Unicrop (L. angustifolius L.) grown at low (10 plants m-2) and high (93 and 83 plants m-2, Ultra and Unicrop respectively) densities. Dry weight increase of flowers on the main-stem inflorescence and first lateral below the main-stem were compared at different floral stages. Maximum flower weight was reached just prior to the open flower stage and remained constant or declined until a pod formed or abscission occurred. The time period between maximum flower weight and pod formation or abscission was up to 10 days. Emergence of the inflorescence was earlier and the first flower of Ultra opened 10 days before Unicrop. Development of each terminal raceme (inflorescence) was acropetal, with pods having formed on lower flower nodes when terminal flowers were still quite immature. Laterals forming the next generation of inflorescences grew from axillary leaf buds below an inflorescence while it was in full flower. Sources of competition from connected reproductive and vegetative metabolic sinks are discussed. © 1979, Annals of Botany Company.