Effect of agronomic biofortification with zinc and ironon yield and economic returns of foxtail millet (Setaria italica L.)

Introduction

Millets are climate-resilient, nutrient-rich cereals well adapted to arid and semi-arid regions and low-input farming systems. Their short duration, low water requirement and adaptability to marginal soil and unfavourable environments make them important for sustainable food and nutritional security. They are rich in carbohydrates, protein, dietary fibre and essential minerals such as Fe, Zn, calcium and magnesium and are therefore recognized as "nutri-cereals" (Saleh et al., 2013) [1] . Foxtail millet (Setaria italica L.) is an ancient, short-duration C 4 cereal with high photosynthetic efficiency and good adaptation to moisture-limited environments. In India, millets occupy about 12.19 million ha, producing 15.38 million tonnes with an average productivity of 1.26 t ha -1 (Anon., 2024) [2] . In Karnataka, foxtail millet is cultivated on approximately 9,000 ha, producing 12,141 tonnes with a productivity of 1,349 kg ha -1 (Anon., 2023) [3] . Despite its adaptability, its productivity remains relatively low, necessitating improved nutrient-management strategies. Zinc and Fe deficiencies are major contributors to global "hidden hunger", affecting human growth, metabolism and overall health (Anon., 2013) [4] . Nearly half of the world's cereal-growing soils have inadequate plant-available Zn, which can restrict crop productivity and grain Zn concentration (Cakmak, 2008) [5] . Similarly, Fe deficiency can impair chlorophyll formation, physiological activity and plant growth (Zhang et al., 2008) [6] . Agronomic biofortification through fertilizers application provides a practical and relatively rapid approach to increase micronutrient concentration in edible plant parts. However, Zn and Fe availability is often restricted in alkaline and calcareous soils. Soil and foliar application of ZnSO 4 and FeSO 4 can improve nutrient availability, uptake and translocation to grain. Therefore, the present study was undertaken to evaluate Zn and Fe application strategies for improving yield, grain micronutrient accumulation and economic returns in foxtail millet and to identify an effective and economically feasible nutrient-management practice for sustainable production and nutritional security.

Material and methods

The experiment was conducted at the Experimental Block of College of Agriculture, Bheemarayanagudi, (UAS, Raichur) which lies in the North Eastern Dry Zone of Karnataka (Zone-II). It is located at 16º15' N latitude, 77º21' E longitude and at an elevation of 389 meters above mean sea level. The experiment design followed was RCBD with nine treatment combinations and three replications viz., T 1: Control, T 2: Soil application of ZnSO 4 @ 5 kg ha -1 , T 3: Soil application of FeSO 4 @ 5 kg ha -1 , T 4: Soil application of ZnSO 4 and FeSO 4 @ 5 kg ha -1 each, T 5: Foliar spray of ZnSO 4 @ 0.5 % at 40 DAS, T 6: Foliar spray of FeSO 4 @ 0.5 % at 40 DAS, T 7: Foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS, T 8: Soil application of ZnSO 4 and FeSO 4 @ 2.5 kg ha -1 each + Foliar spray of ZnSO 4 and FeSO 4 @ 0.25 % each at 40 DAS, T 9: Soil application of ZnSO 4 and FeSO 4 @ 5 kg ha -1 each + Foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS. Foxtail millet variety HN-46, recommended for Zones I-III of Karnataka, was sown at 30 × 10 cm spacing in gross and net plot sizes of 4.8 × 3.6 m and 3.6 × 3.2 m, respectively. The crop was sown on 5 th November 2025 and harvested at physiological maturity on 28 th January 2026. Recommended FYM (6 t ha -1 ) and NPK (30:15:15 kg ha -1 ) were applied, while ZnSO 4 and FeSO 4 were applied through soil and foliar methods as per the treatments. Soil application was done at sowing, whereas foliar sprays were applied at 40 DAS using a knapsack sprayer with 500 l ha -1 spray volume. The FeSO 4 solution was appropriately neutralized before spraying to minimize leaf scorching. Standard agronomic practices, including protective irrigation, manual weeding and plant protection measures, were followed throughout the crop period. The experimental data were sta-tistically analyzed following the procedure suggested by Panse et al. (1967) [7] .

Results and discussion

Yield and yield parameters

Economic yield is the cumulative result of physiological and biochemical processes during crop growth, influenced by plant morphology, biomass accumulation and assimilate partitioning. Adequate and balanced availability of resources, particularly Zn and Fe, plays a vital role in improving yield attributes and overall crop productivity.

The results revealed significant differences among the treatments with respect to yield and yield attributes, namely ear head length (cm), ear head weight per plant (g), number of ear heads per meter, grain yield (kg ha -1 ) and straw yield (kg ha -1 ). These variations were brought about by effect of the agronomic biofortification of zinc and iron. The detailed results were presented in Table 1 and represented in fig. 1.

The treatment receiving soil application of ZnSO 4 and FeSO 4 @ 5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS recorded significantly higher ear head length (19.9 cm), which was statistically on par with soil application of ZnSO 4 and FeSO 4 @ 2.5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.25 % each at 40 DAS (18.0 cm). Whereas, the control was recorded significantly lower ear head length (15.5 cm). The increased ear head length may be attributed to the synergistic effects of Zn and Fe in promoting auxin synthesis, enzyme activity, chlorophyll formation, photosynthesis and assimilate translocation, thereby enhancing reproductive development and ear head elongation. Similar results founded by Qureshi et al. (2021) [8] and Krupashree et al. (2022) [9] .

Figure 1. Yield parameters of foxtail millet as influenced by agronomic biofortification of zinc and iron

Among different treatments, the treatment soil application of ZnSO 4 and FeSO 4 @ 5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS recorded significantly higher ear head weight (8.8 g plant -1 ). While, the control recorded the significantly lower ear head weight (5.8 g plant -1 ). Remaining treatments recorded intermediate values. Combined soil and foliar application of ZnSO 4 and FeSO 4 enhanced photosynthesis, assimilate production and translocation to developing ear heads. ; FYM @ 6 t ha -1 is common for all the treatments. Half of N, entire P, K was applied as basal and remaining half of N was top dressed at 30 days after sowing.

DAS: Days After Sowing.

Number of ear heads m -1

Among different treatments, soil application of ZnSO 4 and FeSO 4 @ 5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS recorded significantly higher number of ear heads (36.0 m -1 ), while it remained statistically on par with soil application of ZnSO 4 and FeSO 4 @ 2.5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.25 % each at 40 DAS (34.7 m -1

) and foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS (34.0 m -1 ). Whereas, control was recorded significantly lower number of ear heads (18.9 m -1

). Combined Zn and Fe application enhanced tiller production, productive tiller survival and reproductive development, thereby increasing ear head formation. Improved enzyme activity, chlorophyll synthesis, photosynthesis and assimilate translocation under balanced Zn and Fe nutrition favoured ear head initiation and development. Similar improvements in foxtail millet growth and yield attributes under Zn and Fe nutrition were reported by White et al. (2009) [10] , Qureshi et al. (2021) [8] and Krupashree et al. (2022) [9] .

The combined soil and foliar treatments produced the higher conversion of tillers into productive tillers. Soil application of ZnSO 4 and FeSO 4 @ 5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS recorded significantly higher number of productive tillers 45.9 m -1 , followed by soil application of ZnSO 4 and FeSO 4 @ 2.5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.25 % each at 40 DAS, 44.5 m -1

. Whereas, significantly lower productive tillers were recorded in control (21.8 m -1

). The balanced availability of Zn and Fe also enhances nutrient uptake and dry matter accumulation, resulting in a greater number of productive tillers. Similar improvement was reported in foxtail millet under Zn and Fe nutrition through enriched organics by Krupashree et al. (2022) [9] .

Among the different agronomic biofortification treatments, soil application of ZnSO 4 and FeSO 4 @ 5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS recorded significantly higher grain yield (2047 kg ha -1 ) and 19.8 % higher grain yield than the control. However it was found statistically on par with soil application of ZnSO 4 and FeSO 4 @ 2.5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.25 % each at 40 DAS (1960 kg ha -1 ) and foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS (1864 kg ha -1 ). The lower grain yield was recorded in the control (1709 kg ha -1 ).

A similar trend was observed in straw yield as that of grain yield. The treatment receiving soil application of ZnSO 4 and FeSO 4 @ 5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS recorded significantly higher straw yield (5106 kg ha -1 ) and it was found statistically on par with soil application ZnSO 4 and FeSO 4 @ 2.5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.25 % each at 40 DAS (4829 kg ha -1 ), Whereas significantly lower straw yield was obtained in the control (4290 kg ha -1 ). The significant improvement in yield and yield attributes such as ear head length, ear head weight per plant, number of ear heads per meter, grain yield and straw yield under zinc and iron biofortification of foxtail millet may be attributed to the complementary physiological roles of these micronutrients in enhancing plant growth, photosynthetic efficiency, nutrient utilization and assimilate translocation. Zinc plays an important role in auxin synthesis, enzyme activation, protein metabolism and pollen development, whereas iron is indispensable for chlorophyll synthesis, electron transport and energy generation during photosynthesis. Adequate availability of both micronutrients promotes vigorous vegetative growth, efficient carbohydrate production and effective partitioning of assimilates towards reproductive sinks, thereby improving grain formation and final yield. Similar results quoted by White et al. (2009) [10] , Yadav et al. (2011) [11] , Sathisha et al. (2019) [12] and Krupashree et al. (2022) [9] in foxtail millet.

Economics

The results on cost of cultivation (₹ ha -1 ), gross returns (₹ ha -1 ), net returns (₹ ha -1 ) and benefit cost ratio as influenced by agronomic biofortification of zinc and iron were furnished in Table 2 and depicted in Fig. 2.

The cost of cultivation varied among the treatments depending on the method and level of zinc and iron application. The higher cost of cultivation was incurred with soil application of ZnSO 4 and FeSO 4 @ 5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS, (₹ 39,171 ha -1

), followed by soil application of ZnSO 4 and FeSO 4 @ 2.5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.25 % each at 40 DAS (₹ 38,862 ha -1 ). The control recorded lower cost of cultivation (₹ 36,493 ha -1 ). The higher cost of cultivation under zinc and iron biofortification treatments was primarily due to the additional expenditure incurred on ZnSO 4 and FeSO 4 fertilizers and their foliar application, including labour charges. Treatments involving both soil and foliar application recorded the highest cultivation cost because of the increased input requirement. However, the additional investment in micronutrient application contributed to improved crop growth, yield and grain micronutrient enrichment. Similar economic trends under agronomic biofortification of sorghum have been reported by Sudeep et al. (2025) [13] .

Among different treatments, the treatment receiving soil application of ZnSO 4 and FeSO 4 @ 5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS recorded significantly higher gross returns (₹ 78,793 ha -1 ), which was statistically on par with soil application of ZnSO 4 and FeSO 4 @ 2.5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.25 % each at 40 DAS (₹ 75,401 ha -1 ). The control recorded the significantly lower gross returns (₹ 65,825 ha -1 ). Note: Men and women labour @ ₹ 500 each, Bullock pair @ ₹ 1200 day -1 , Tractor hiring @ ₹ 1000 hr -1 , FYM @ ₹1100 t -1 , Urea @ ₹ 5.37 kg -1 , DAP @ ₹ 27 kg -1 , MoP @ ₹ 34 kg -1 , ZnSO 4 @ ₹ 50 kg -1 , FeSO 4 @ ₹ 30 kg -1 , Seeds @ ₹ 80 kg -1 , Foxtail millet grains @ ₹ 3600 q -1 , Straw @ ₹ 100 q -1 , Marketing charges @ 3% of the produce. RDF -30:15:15 kg N:P 2 O 5 :K 2 O ha -1 ; FYM @ 6 t ha -1 is common for all the treatments. Half of N, entire P, K was applied as basal and remaining half of N was top dressed at 30 days after sowing. DAS: Days After Sowing.

The treatment receiving soil application of ZnSO 4 and FeSO 4 @ 5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS recorded the significantly higher net returns (₹ 39,622 ha -1 ), which was statistically on par with soil application of ZnSO 4 and FeSO 4 @ 2.5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.25 % each at 40 DAS (₹ 36,539 ha -1 ), foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS (₹ 34,044 ha -1 ) and soil application of ZnSO 4 and FeSO 4 @ 5 kg ha -1 each (₹ 33,146 ha -1 ). The control was recorded significantly lower net returns (₹ 29,333 ha -1

). [14] , Krupashree et al. (2022) [9] and in sorghum by Sudeep et al. (2025) [13] .

Benefit cost ratio (B:C)

Among different treatments, application of treatment receiving soil application of ZnSO 4 and FeSO 4 @ 5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS recorded the significantly higher B:C (2.01), which was statistically on par with soil application of ZnSO 4 and FeSO 4 @ 2.5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.25 % each at 40 DAS (1.94), foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS (1.90), soil application of ZnSO 4 and FeSO 4 @ 5 kg ha -1 each (1.87) and foliar spray of ZnSO 4 @ 0.5 % (1.87). The control was recorded significantly lower B:C (1.79). The increased benefit cost ratio under the combined basal and foliar zinc application treatment may be attributed to enhanced yield performance and higher gross returns over the cost of cultivation resulted in increased benefit cost ratio. Similar results were reported by Anilkumar et al. (2017) [15] , Vinita et al. (2021) [16] , Krupashree et al. (2022) [9] and Sudeep et al. (2025) [13] .

Conclusion

Soil application of ZnSO 4 and FeSO 4 @ 5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS along with RDF was found to be the most effective agronomic biofortification treatment for foxtail millet, recorded 19 % higher grain and straw yield over control along with maximum gross returns, net returns and B:C followed by soil application of ZnSO 4 and FeSO 4 @ 5 kg ha -1 each + foliar spray of ZnSO 4 and FeSO 4 @ 0.5 % each at 40 DAS along with RDF.

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17. How to cite this article: Agnesh, Chavan M, Kulkarni S, Hiremath K, Raja. Effect of agronomic biofortification with zinc and iron on yield and economic returns of foxtail millet (Setaria italica L.). International Journal of Agriculture and Food Science. 2026;8(10):04-09. doi: https://www.doi.org/10.33545/26
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