Effect of Foliar Spray of Various Concentrations of GA3 on Growth and Yield Attributes of African Marigold (Tagetes erecta Linn.) cv. Pusa Narangi

Abstract

African marigold (Tagetes erecta Linn.) is a commercially important flower crop owing to its attractive blooms, prolific flowering, short crop duration and broad adaptability. Improvement of flower productivity requires the identification of appropriate plant growth regulator concentrations that can effectively enhance vegetative growth, flowering and yield. Therefore, the present investigation was conducted to assess the response of African marigold cv. Pusa Narangi to foliar application of different concentrations of gibberellic acid (GA₃) and to determine the most effective concentration for improving flower production. The experiment was carried out during the winter season of 2016–17 at the Garden Research Farm, Department of Horticulture, Udai Pratap Autonomous College, Varanasi, India. The experiment was arranged in a Randomized Block Design with three replications and five treatments, consisting of GA₃ concentrations of 80, 120, 160 and 200 ppm, along with an untreated control (0 ppm GA₃) sprayed with distilled water. The application of GA₃ significantly affected plant height, number of branches per plant, number of leaves per plant at 60 days after spraying, flower diameter, fresh flower weight, number of flowers per plant and flower yield per plant. However, the treatment effects on the number of leaves per plant at 30 days after spraying and days to first flowering were statistically non-significant. The maximum plant height at 30 and 60 days after spraying (67.93 and 87.55 cm, respectively) and the highest number of branches (23.15 and 34.72 plant⁻¹, respectively) were recorded with GA₃ at 200 ppm. The greatest number of leaves at 60 days after spraying (241.80 plant⁻¹) was obtained with 160 ppm GA₃. Application of GA₃ at 120 ppm resulted in the largest flower diameter (6.03 cm), while the highest fresh flower weight (5.87 g) was recorded with 160 ppm. The maximum number of flowers (37.83 plant⁻¹) and flower yield (202.49 g plant⁻¹) were obtained with 120 ppm GA₃. Although days to first flowering were not significantly influenced by GA₃ treatments, the earliest flowering (66.26 days) was observed with 80 ppm. Overall, foliar application of GA₃ at 120 ppm showed the most favourable response for enhancing flowering and flower yield of African marigold cv. Pusa Narangi and may be recommended for commercial cultivation under comparable agro-climatic conditions.