Impact of growth regulators and micronutrients on yield and its attributing traits in tomato (Solanum lycopersicum L.)

Introduction

Tomato (Solanum lycopersicum L.) belongs to the family Solanaceae and is one of the most widely cultivated vegetable crops in the world. It is an important protective food rich in vitamins, minerals, and antioxidants such as lycopene. India ranks second in tomato production after China and tomato occupies a prominent position among vegetable crops cultivated in the country. Tomato fruits are consumed in fresh as well as processed forms including ketchup, puree, soup, sauce, juice, paste, and powder. The crop is highly remunerative and contributes significantly to nutritional security and farmer income. The fruit contains appreciable quantities of vitamin A, vitamin C, calcium, phosphorus, and iron.Plant growth regulators (PGRs) play an important role in regulating physiological processes such as cell division, elongation, flowering, fruit setting, and ripening. Gibberellic acid (GA₃) and Naphthalene Acetic Acid (NAA) are commonly used growth regulators known to improve plant growth, flowering, and yield in tomato. Micronutrients such as zinc, boron, iron, copper, and manganese are equally important for proper plant growth and fruit development. Zinc plays a key role in enzyme activation and protein synthesis, whereas boron is essential for pollen germination, fruit setting, and translocation of sugars. Foliar application of micronutrients improves vegetative growth, photosynthesis, fruit quality, and overall productivity.

Materials and Methods

The present investigation was conducted during the rabi season at the Faculty of Agricultural Sciences and Allied Industries, Rama University, Kanpur, Uttar Pradesh. The experiment was laid out in a Randomized Block Design (RBD) with three replications. Twelve treatments were evaluated with a plot size of 8.1 m². The crop used was tomato variety Kashi Aman. The spacing adopted was 60 cm × 45 cm. Different treatments comprising growth regulators and micronutrients were applied as foliar sprays at appropriate growth stages. Details of Treatments are-T₁: Control, T₂: Borax @ 0.2%, T₃: Zinc sulphate @ 0.5%, T₄: Micronutrient mixture @ 0.5%, T₅: NAA @ 50 ppm, T₆: NAA @ 50 ppm + Borax @ 0.2%, T₇: NAA @ 50 ppm + Zinc sulphate @ 0.5%, T₈: NAA @ 50 ppm + Micronutrient mixture @ 0.5%,T₉: GA₃ @ 50 ppm, T₁₀: GA₃ @ 50 ppm + Borax @ 0.2%, T₁₁: GA₃ @ 50 ppm + Zinc sulphate @ 0.5%, T₁₂: GA₃ @ 50 ppm + Micronutrient mixture @ 0.5%.

Results and Discussion

Growth Parameters

Application of GA₃ along with micronutrient mixture significantly increased plant height and number of branches per plant. The maximum plant height (96.42 cm) and number of branches (13.24) at harvest were recorded in T₈ (GA₃ @ 50 ppm + micronutrient mixture @ 0.5%). This enhanced vegetative growth can be attributed to increased cell elongation, improved nutrient absorption, and higher photosynthetic activity induced by the synergistic effect of GA₃ and micronutrients. These findings are in agreement with Uddain et al. (2009) [1] , who reported that GA₃ @ 30 ppm significantly increased plant height and number of branches in tomato. Similarly, Jakhar et al. (2018) [3] observed maximum vegetative growth with GA₃ @ 50 ppm. Prasad et al. (2013) [2] also reported significant improvement in growth attributes with GA₃ application. The role of micronutrients in enhancing cell division and enzyme activity further supports the superior performance of combined treatments. [3,6] , who reported earlier flowering with GA₃ application. The positive effect of boron and zinc on reproductive development further justifies the superior performance of combined treatments. [4,5] , who reported significant improvement in fruit number and size with combined application of zinc and boron. Prasad et al. (2013) [2] also documented enhanced yield attributes with GA₃ @ 80 ppm.

Fruit Yield

The highest average fruit weight (102.64 g), yield per plant (2.96 kg), and yield per hectare (632.76 q/ha) were recorded in T₈. The synergistic effect of GA₃ and micronutrients improved nutrient use efficiency and assimilate partitioning towards fruits.

These results are strongly supported by Kushwaha et al. (2025) [6] , who reported maximum yield with GA₃ @ 50 ppm + micronutrient mixture. Similar findings were documented by Jakhar et al. (2018) and Ali et al. (2015) [3,4] . [6,7] , who observed improved fruit quality with combined application of GA₃ and micronutrients.

Conclusion

The present investigation clearly demonstrated that foliar application of plant growth regulators and micronutrients significantly influenced growth, flowering, fruit yield, quality, and economics of tomato cultivation. Among the treatments, GA₃ @ 50 ppm combined with micronutrient mixture @ 0.5% proved most effective in improving plant growth, fruit yield, fruit quality, and profitability. Therefore, combined application of growth regulators and micronutrients may be recommended for commercial tomato cultivation to achieve higher productivity and better economic returns under subtropical conditions.

References

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