Effect of plant growth regulators on growth, quality and yield of Dendrobium orchid under polyhouse

Present investigation was carried to study the effect of different plant growth regulators (PGRs) on vegetative growth, flowering and yield of Dendrobium orchid var. Sonia 17 grown under naturally ventilated polyhouse. The experiment was laid out in completely randomized design having 13 treatments of PGRs in increasing proportion of their concentration viz., Gibberellic acid (GA₃: 50, 100, 150 ppm), Kinetin (100, 200, 300 ppm), Benzyladenine (BA: 50, 100, 150 ppm) and Brassinosteroid (BRs: 0.25, 0.50, 0.75 ppm). The results of pooled analysis of three years indicated that, bimonthly spray of 50 ppm GA₃ on Dendrobium orchid resulted in maximum plant height (47.32 cm), leaves per plant (13.53) and number of shoots per plant (9.13). The maximum spike length (35.92 cm), florets per spike (11.31), spikes per plant (4.38), spikes per 500 m² (15861.11), longevity of spike (47.24 days) and vase life (22.59 days) was also recorded with 50 ppm GA₃. However, application of different PGRs did not have significant effect on leaf area, roots per plant, days to first spike emergence, days to first flowering and floret size. The foliar application of GA₃ @ 50 ppm was found better for getting higher spike yield and better flower quality of Dendrobium orchid under naturally ventilated polyhouse.