Effect of plant growth regulators on growth and yield of periwinkle [catharanthus roseus (l.) g. don] cv. rose purple flowered

The study on the effect of plant growth regulators on growth and yield of Periwinkle [Catharanthus roseus (L.) G. Don] cv. Rose purple flowered was carried out in the medicinal unit, Department of Horticulture, Faculty of Agriculture, Annamalai University, Annamalai nagar, Tamil Nadu. This experiment is carried out in Randomized block design with 10 different treatments replicated thrice. The experiment comprised of control and three growth regulators with their three levels viz., Gibberllic acid @100, 200 and 300 ppm, Naphthalene acetic acid @50, 100 and 150 ppm, Cycocel @ 250, 500 and 750 ppm were applied as foliar application. Observations of biometric characters like plant height, number of branches plant-1, number of leaves plant-1, leaf area, total chlorophyll content, dry matter production (kg ha-1), number of flowers plant-1, dry leaf yield plant-1 (g), total dry leaf yield plant-1 (g), dry leaf yield plot-1 (g) and dry leaf yield ha-1 (kg) on final harvest were observed. The treatments significantly influenced the growth and yield of periwinkle and the results revealed that application of GA3 @ 300 ppm in the treatment (T3) recorded the maximum performance on growth and yield characters. Hence this treatment was found as superior than the rest in and ultimately increasing the dry leaf yield (2784.16 kg ha-1) when compare to control.