Influence of concentration and mode of application of different growth regulators on dendrobium hybrid Thongchai Gold

An experiment was conducted to determine the influence of concentration and mode of application of different growth regulators on growth and yield of Dendrobium hybrid “Thongchai Gold” in subtropical cool climate zone. Various concentrations of GA 3 and BA were applied as foliar spray and drenching mode. GA 100 ppm in combination with BA 100 ppm followed by GA 200 ppm 3 3 increased the plant height (31.63 cm), number of shoots per plant (5.17), cane girth (1.71 cm), number of leaves per cane (8.21), internodal length (3.19 cm), spike girth (0.45 cm), number of flowers per spike (12.63) and number of spikes per cane (2.80). The spike length (29.38 cm) was noticed highest in GA 50 ppm and rachis length (19.66 cm) was observed highest in GA 200 ppm. 3 3 Growth regulators and mode of applications also influenced nutrient content (NPK) of plants. Among the mode of applications, media drenching with the different growth regulator treatment was found to be best for the Dendrobium orchids.