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

Seedlings 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.     

Photoperiod and Temperature Effects on Late Developmental Stages of Stylosanthes guianensis

Seedlings of Stylosanthes guianensis var. guianensis cv. Cookand S. guianensis var. pauciflora cv. Bandeirante were defoliatedand placed in a naturally lit glasshouse at 23/18 °C, 28/23°C or 33/28 °C (day/night). After exposure to 14 h daysand after floral induction with 30 cycles of 11 h, plants wereallocated to 11, 12, 13 or 14 h during flowering and seed formation. Floral initiation occurred after 10–15 short-day cycles.Flower appearance was hastened by warm temperatures and spikenumber per plant at 20 d after flower appearance was negativelyrelated to temperature and greater in Cook than in Bandeirante.Exposure to 13- and 14-h days reduced the continued differentiationof inflorescences in Bandeirante, and in Cook in warm temperatures.Floret number per spike was greatest at 23/18 °C and a higherproportion of florets aborted in Bandeirante at 33/ 28 °C.Variations in seed setting of the bi-articulate loment of Bandeiranteare described. Highest potential seed yield occurred if afterfloral induction 11 or 12 h days were maintained with 23/18°C or 28/23 °C temperatures. Photoperiod, temperature, development, Stylosanthes guianensis, flowering