Impact of GA₃ NAA and IBA foliar sprays on growth, yield and quality of cauliflower (Brassica oleracea var. botrytis L.) cv. Pusa Snowball

Introduction

Cauliflower (Brassica oleracea var. botrytis L.) belongs to the Brassicaceae family and is cultivated worldwide for its edible, compact curd formed by arrested floral branches. It is a cool-season crop highly sensitive to temperature extremes, which can trigger disorders such as buttoning or ricey curds, thereby reducing marketable yield and quality. India ranks second globally in cauliflower production after China, contributing significantly to national vegetable output. Uttar Pradesh is a major producer, with stable area and production in recent years. The edible curd is nutritionally rich, low in calories, and provides dietary fibre, vitamins, minerals, and antioxidants. Despite its importance, cauliflower productivity often remains suboptimal due to environmental stresses and physiological limitations in curd formation. Plant Growth Regulators (PGRs) such as Gibberellic Acid (GA₃), Naphthalene Acetic Acid (NAA), and Indole-3-Butyric Acid (IBA) can modulate hormonal balance, promote vegetative vigour, accelerate curd initiation, and improve assimilate partitioning toward reproductive structures.

Foliar application of PGRs is a practical, low-cost method that enhances nutrient uptake and physiological efficiency in vegetable crops. Previous studies have shown promising results with GA₃ and NAA in cole crops, but information on their optimal concentrations and combinations for the latematuring cv. Pusa Snowball under Uttar Pradesh conditions is limited. The present investigation was therefore undertaken to standardize effective PGR treatments for improving growth, curd formation, yield, quality, and economic returns of cauliflower cv. Pusa Snowball.

Materials and Methods

The field experiment was conducted during the rabi season (September 2025-February 2026) at the Agricultural Research Field, Rama University, Mandhana, Kanpur (Uttar Pradesh). The experimental site has a subtropical climate with sandy loam soil (pH 7.45, EC 0.38 dS m⁻¹, organic carbon 0.48%, available N 195 kg ha⁻¹, P 21 kg ha⁻¹, K 235 kg ha⁻¹). Cauliflower cv. Pusa Snowball, a late-maturing variety known for compact, snow-white curds, was used. Seeds www.extensionjournal.com were sown in the nursery in early September, and 25-dayold seedlings were transplanted in mid-October at 60 cm × 45 cm spacing. The experiment was laid out in a randomized block design with eight treatments and three replications. Plot size was 2.16 m² (1.8 m × 1.2 m), accommodating eight plants per plot.

Treatments

T₀: Control (Water spray) T₁: GA₃ @ 75 ppm T₂: GA₃ @ 125 ppm T₃: NAA @ 50 ppm T₄: NAA @ 100 ppm T₅: IBA @ 10 ppm T₆: IBA @ 20 ppm T₇: GA₃ @ 50 ppm + NAA @ 50 ppm Foliar sprays were applied three times at 20, 35, and 50 DAT using a knapsack sprayer. Standard cultural practices were followed uniformly, including well-rotten FYM @ 25 t ha⁻¹ and recommended NPK (120:60:80 kg ha⁻¹). Irrigation, weeding, and plant protection measures were applied as needed. Observations were recorded on growth parameters (plant height, number of leaves, stem diameter at 60 DAT), phenological traits (days to curd formation and marketable curd stage), attributes (curd diameter, curd weight per plant, curd yield per plot and per hectare), and economic parameters. Data were statistically analyzed using analysis of variance (ANOVA) for RBD, and treatment means were compared using Critical Difference (CD) at P = 0.05.

Results and Discussion

Growth parameters PGR treatments significantly influenced vegetative growth parameters at 60 DAT (Table 1). The combination treatment T₇ (GA₃ 50 ppm + NAA 50 ppm) recorded the maximum plant height (58.9 cm), number of leaves per plant (19.6), and stem diameter (2.58 cm). These values were statistically superior to the control (T₀: 48.2 cm height, 14.8 leaves, 1.85 cm stem diameter) and most other single-PGR treatments. The synergistic interaction between GA₃ (which promotes cell elongation and internodal lengthening) and NAA (which enhances cell division and apical dominance) likely stimulated vigorous shoot growth and expanded photosynthetic surface area, leading to improved dry matter accumulation. These observations are consistent with earlier findings.

Yield and Yield attributes

T₇ significantly shortened the time to curd formation (55 DAT) and marketable curd stage (78 DAT) compared to the control (higher by 13-14 days). It also produced the largest curd diameter (19.8 cm) and heaviest curd weight per plant (742 g). Consequently, curd yield reached a maximum of 5.46 kg per plot and 278.9 q ha⁻¹ markedly higher than all other treatments. The accelerated phenology and enhanced curd development under T₇ can be attributed to improved hormonal balance that favoured assimilate translocation toward the curd (sink) and reduced competition from excessive vegetative growth at higher PGR concentrations. These results corroborate Kaur and Mal (2018) [1] , who observed maximum curd diameter and weight with 50 ppm GA₃, and Chanwala et al. (2019) [3] , who reported synergistic yield gains from NAA + GA₃ combinations in broccoli. The present findings further confirm that moderate combined doses optimize curd compactness and size without inducing disorders such as riceyness or buttoning.

Economics of production

Economic analysis revealed that T₇ delivered the highest gross return (₹4,18,350 ha⁻¹), net return (₹2,21,850 ha⁻¹), and benefit-cost ratio (2.13). The modest additional cost of PGR application was more than compensated by the substantial yield increase. These economic advantages highlight the practical viability of the treatment for resource-constrained farmers.

Conclusion

The combined foliar application of GA₃ 50 ppm + NAA 50 ppm applied at 20, 35, and 50 DAT proved to be the most effective treatment for cauliflower cv. Pusa Snowball. It significantly enhanced vegetative growth, advanced curd maturity, increased curd size and weight, boosted marketable yield to 278.9 q ha⁻¹, and delivered the highest economic returns (B:C ratio 2.13). This treatment can be recommended to farmers in the Middle Gangetic Plain for realizing the full yield potential of the crop while improving profitability. Further studies on integration with micronutrients or biofertilizers may provide additional benefits.

References

1. Kaur P, Mal D. Effect of foliar spray of NAA and GA₃ on growth, curd formation and yield of cauliflower. Journal of Pharmacognosy and Phytochemistry. 2018;7(3):2805-2807.
2. Reza M, et al. Effect of GA₃ concentrations on broccoli growth and yield parameters. International Journal of Horticultural Science and Technology. 2015;2(1):45-53.
3. Chanwala K, et al. Combined effect of NAA and GA₃ on sprouting broccoli. Vegetable Science. 2019;46(2):112-119.
4. Akhter S, et al. Impact of plant growth regulators on the growth and yield of cole crops: A comprehensive review. Journal of Horticultural Research. 2019;27(1):89-98.
5. Jadon AS, et al. Evaluation of different PGRs on growth, yield and quality components of cauliflower (Brassica oleracea var. botrytis). Indian Journal of Agricultural Sciences. 2015;85(4):512-518.
6. Verma SK, et al. Influence of gibberellic acid and naphthalene acetic acid on growth and yield of cabbage (Brassica oleracea var. capitata). Annals of Plant and Soil Research. 2018;20(3):264-270.
7. Meena ML, et al. Effect of plant growth regulators on growth, yield and quality of broccoli (Brassica oleracea var. italica) cv. KTS-1. Indian Journal of Horticulture. 2018;75(2):245-252.