Photoperiod and temperature effects on late developmental stages of Stylosanthes guianensis

Seedlings of Stylosanthes guianensis var. guianensis cv. Cook and S. guianensis var. pauciflora cv. Bandeirante were defoliated and placed in a naturally lit glasshouse at 23/18 °C, 28/23 °C or 33/28 °C (day/night). After exposure to 14 h days and after floral induction with 30 cycles of 11 h, plants were allocated 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 spike number per plant at 20 d after flower appearance was negatively related to temperature and greater in Cook than in Bandeirante. Exposure to 13- and 14-h days reduced the continued differentiation of inflorescences in Bandeirante, and in Cook in warm temperatures. Floret number per spike was greatest at 23/18 °C and a higher proportion of florets aborted in Bandeirante at 33/ 28 °C. Variations in seed setting of the bi-articulate loment of Bandeirante are described. Highest potential seed yield occurred if after floral induction 11 or 12 h days were maintained with 23/18 °C or 28/23 °C temperatures