Effect of growth regulators and micronutrients on flowering and yield of jasmine

Abstract:

Jasmine (Jasminum sambac) has been cultivated in Southeast Asia for more than two thousand years, yet commercial growers still struggle with uneven flowering and low per-plant yields. This research evaluated the effects of three growth regulator-micronutrient combinations on vegetative growth, flowering behaviour, and flower yield of jasmine cv. Mali Son under the humid sub-tropical conditions of Chiang Mai, Thailand. The trial was laid out in a randomised block design with four treatments (T1: GA3 200 ppm + ZnSO₄ 0.5%; T2: NAA 150 ppm + FeSO₄ 0.3%; T3: GA3 100 ppm + NAA 100 ppm + micronutrient mix 0.4%; T4: water control) and three replications over two consecutive years (2022-23 and 2023-24). T3 recorded the highest mean flower yield (305.7 g/plant/year), 49.6% above control, along with earlier bud initiation by 7 days, greater flowers per cluster (12.1 vs. 6.8), and improved essential oil content (0.47% vs. 0.31%). All growth-regulator treatments significantly outperformed the control (p<0.05) for most parameters. Combined GA3-NAA spray with micronutrient supplementation can be recommended for commercial jasmine production in northern Thailand.