Time of sowing and temperature effects on the flowering of Stylosanthes guianensis

Abstract

SUMMARYSeedlings of Stylosanthes guianensis var. guianensis cv. Cook and of two selections of S. guianensis var. pauciflora (CIAT 1280 and CIAT 1062) were grown at day/night temperatures of 20°/25°, 30°/25°, and 35°/30°C in a naturally‐lit glasshouse at latitude 27°30'S. Sowings were made in decreasing daylength at 30‐day intervals from 22 January to 21 May.Cv. Cook and the CIAT 1280 selection did not flower fully if sown after 22 January and the CIAT 1062 selection did not flower if sown after 22 March. This is interpreted as a long‐short day flowering response. Usually, flowers were initiated earlier and at a lower node at 25†/20°C than at the warmer temperatures. At 25†/20°C the first flowers to appear were produced predominantly at the terminal apex of the main stem in cv. Cook and the CIAT 1062 selection, but not in the CIAT 1280 selection. At the two warmer temperatures first flowers were more commonly produced at the terminal apex of primary, secondary and tertiary branches. There were more inflorescences per plant on earlier than later sown plants when measured 21 days from appearance of the first flower and the most inflorescences were produced by cv. Cook at 25†/20°C, by selection CIAT 1062 at 30°/25°C, and by CIAT 1280 at 35°/30°C.