Effects of short day and temperature on growth and flowering of Vanda hybrid

Vanda is an economically important orchid in Thailand. However, information on Vanda flowering control is still limited. Therefore, this research aimed to study some environmental factors affecting the growth and flowering of a Vanda hybrid. Vanda ‘Red Spot’ were grown under short day (SD) conditions (16 h for dark period) for 2, 3 and 4 weeks and moved to the evaporative cooling greenhouse and compared to those grown in the evaporative cooling greenhouse or a 50% shading greenhouse throughout the experiment (control treatment). The experimental design was a complete randomized design (CRD), with 5 treatments and 20 replications per treatment. The results showed that plants grown under SDs for 4 weeks gave the highest percentage of flowering, whereas plants grown in 50% shading greenhouses did not flower. Plants grown under SD conditions for 4 weeks also had the widest flowers, with an average of 11.5 cm. Thus, growing in evaporative cooling house stimulated flowering percentage in Vanda.