Impact of Exogenous Application of Growth Regulators on Fruit Attributes and Yield of Strawberry (Fragaria × ananassa Duch.) cv. Winter Dawn

Strawberry (Fragaria × ananassa Duch.) is an economically important fruit crop whose productivity and fruit quality are influenced by environmental conditions, cultivar characteristics and crop management practices. Although exogenous plant growth regulators and biostimulants have been investigated for improving strawberry production, their comparative effects on flowering, fruit attributes and yield of cv. Winter Dawn under the semi-arid subtropical conditions of Haryana remain inadequately documented. The current study was carried out during 2024–25 at K.L. Chadha Farm, SGT University, Gurugram, Haryana, to examine the impact of growth regulators on productivity and fruit quality parameters of strawberry (Fragaria × ananassa Duch.) cv. Winter Dawn. The experiment was conducted using a randomised complete block design with three replications and nine treatments comprising salicylic acid (2.0 and 4.0 mM), triacontanol (5 and 10 μM), ascorbic acid (50 and 100 ppm), humic acid (0.2 and 0.4%) and an untreated control. Significant differences were observed among treatments for flowering, fruit setting and yield characteristics. Humic acid 0.4% resulted in the earliest initial flowering (53.35 days), the earliest final flower opening (68.05 days), the highest fruit set percentage (75.87%), the shortest flowering period (13.98 days). The same treatment also produced the highest number of fruits per plant (22.66), the greatest fruit length (4.53 cm) and the greatest fruit width (3.85 cm). Triacontanol 10 μM resulted in the earliest fruit ripening (92.28 days). Humic acid 0.4% also resulted in the highest fruit weight (17.77 g), the highest fruit volume (21.72 ml), the highest fruit yield per plant (380.46 g) and yield per hectare (11.52 t ha⁻¹). The highest number of achenes was also recorded following the application of humic acid 0.4% (234.19). Overall, pre-harvest application of humic acid 0.4% was the most effective treatment in enhancing flowering, fruit formation and productivity of strawberry cv. Winter Dawn under the semi-arid subtropical climate of Haryana.