Flowering time response of Nasturtium (Tropaeolum majus L.) cultivar ‘Empress of India’ to photoperiod, light integral and temperature using photo-thermal model

Abstract

Experiments were carried out to study flowering response of Nasturtium under four distinct controlled photoperiods (8, 11, 14, and 17 h.d-1), shading materials (0, 20, 30 and 40%) and five temperature regimes (10, 15, 20, 25, and 30°C). A curvilinear facultative response was observed in all experiments. Cultivar ‘Empress of India’ took minimum time to flower when grown under a 17 hr-photoperiod (57 days) however, it was significantly (P<0.05) increased when photoperiod decreased to 8h (83 days). Similarly, days taken to flowering were increased significantly (P<0.05) when plants were grown under low light integrals (40%, 30%, and 20% shade). Flowering was delayed up to 17 days when plants were grown under intense shade (40%). Temperature also had a significant effect on the developmental phases of flower as low temperature (10°C) decreased flowering up to 46 days as compared to plants grown at 25°C. However, the quality of flowering plant (including plant height, spread and leaf number, data not shown) was decreased at higher temperatures (25 and 30°C). Best quality plants were obtained when grown between 15 to 20°C. These findings revealed a prospect of plant scheduling of the flowering time of Nasturtium grown under short day photoperiod to extend their marketing period. A steady supply of this flowering annual can be maintained in the market by grown them under different shades (low light integrals). Similarly, an optimum growing temperature between 15-20°C would also be a beneficial effect on the quality of plant in the market.

Keywords

• nasturtium
• Tropaeolum majus L.
• photoperiod
• light integral
• temperature
• shade
• flowering time