EFFECTS OF TEMPERATURE AND PHOTOPERIOD ON WINGED BEANS [PSOPHOCARPUS-TETRAGONOLOBUS (L) DC]

The effects of temperature and photoperiod on winged beans were studied using 15 University of New Guinea (UPS) selections and five Sri Lanka (SL) selections. They were grown at 25/20 or 30/25 °C day/ night temperature at 11 or 14 h photoperiod with 12 h thermoperiod. Differences in stomatal density were observed among selections and between photoperiods. Higher densities occurred at 14 h photoperiod than at 11 h photoperiod. When stomatal density was high due to a photoperiod or temperature effect, there was a corresponding increase in leaf area and d. wt of plants.Total chlorophyll content at 25/20 °C was higher at 11 h photoperiod than at 14 h photoperiod in all selections while the total chlorophyll content at 30/25 °C varied with the photoperiod and selection.Leaf area of SL selections was greater than that of UPS selections. Also greater leaf area was observed at 14 h photoperiod than at 11 h photoperiod, irrespective of the growing temperature.Temperature was as important as photoperiod in controlling flowering of winged beans. All the UPS selections and two SL selections flowered at 11 h photoperiod at 25/20 °C but failed to flower at the same photoperiod at 30/25 °C indicating an interaction between temperature and photoperiod. It is likely that winged beans have a narrow photoperiodic range, particularly the SL selections. © 1979, Annals of Botany Company.