Assessing the Effect of Plant Growth Regulators on the Vegetative Growth of Gladiolus (Gladiolus grandiflorus L.) var. Pusa Shanti

Abstract

Plant growth regulators can influence corm sprouting and vegetative development in gladiolus, but cultivar- and dose-specific responses require local evaluation. A field experiment was conducted during 2024–2025 at the Horticulture Farm of the Department of Horticulture to assess the effects of gibberellic acid (GA3), 1-naphthaleneacetic acid (NAA), indole-3-butyric acid (IBA), and Cycocel (CCC) on Gladiolus grandiflorus L. var. Pusa Shanti. The experiment was laid out in a randomised block design at a spacing of 30 × 20 cm, with twenty-one corms per plot. Thirteen treatments comprised a control; GA3, NAA, and IBA at 100, 150, and 200 ppm; and CCC at 600, 650, and 700 ppm. Days to corm sprouting, plant height, number of leaves per plant, and leaf area were evaluated. Treatment T3 (GA3 at 150 ppm) produced the earliest corm sprouting (8.50 days), greatest plant height (124.90 cm), highest number of leaves per plant (8.75), and largest leaf area (932.44 cm²). GA3 at 200 ppm also performed favourably but did not exceed GA3 at 150 ppm for the measured traits. CCC treatments delayed sprouting and reduced plant height relative to the control, with CCC at 700 ppm recording 13.00 days to sprouting and a plant height of 98.75 cm. Under the tested conditions, GA3 at 150 ppm was the best-performing treatment for the vegetative growth of Pusa Shanti.