Iron and zinc agronomic fortification enhances nutrient content and uptake in finger millet (Eleusine coracana L.) under south Gujarat condition

Introduction

Finger Millet (Eleusine coracana L. Gaertn.), a member of the Poaceae family and Chloridoidae subfamily, is a vital sustenance crop originating from the Ethiopian Highlands and introduced to India approximately 4000 years ago (Dida et al., 2008) [3] . It ranks third among India's millets in both area (1.29 million ha) and production (2.19 million tonnes), following after sorghum and pearl millet. Finger millet is small-seeded minor cereal with light brown to brick red coloured or dark brown seed coat, which is highly rich in phyto-chemicals such as a phytochemical such as polyphenols and dietary fibers. Finger millet is a good source of nutrients especially fiber and antioxidants which makes it easily and slowly digestible. Consequently, finger millet efficiently helps in controlling the blood glucose levels in diabetic patients. Therefore, finger millet is considered to be ideal food for diabetic individuals due to its low sugar content and slow release of glucose into the body (Kang et al. 2008) [7] . Globally, India is a leading producer of millets alongside nation like Nigeria, Niger, Mali, Burkina Faso, Chad and China. India contributes more than 50 per cent of the world production with an area of 1.2 million ha and a production of 1.75 million tonnes and productivity of 1.7 tonnes ha -1 , respectively. In Gujarat, finger millet is the most important traditional millet crop grown over an area of 11,000 ha. with a productivity of 1435 kg ha -1 and provides vital food and nutritional security to the marginal farmers in the rainfed dry lands and hilly tribal areas of the Dangs, Valsad and Navsari districts of South Gujarat and Panchmahal district of middle Gujarat. (Intwala et. al.,2017) [5] . In 2025, 1,165 kg of finger millet was harvested per hectare in the region with the Dang district taking the lead in millet farming in the state over the past few years. (Anon.,2025). Agronomic biofortification is an effective and accessible way to reach the poor rural masses for enhancing the concentration of essential minerals (Zn and Fe) in their diets. The attempt to alleviate Zn and Fe deficiencies in human beings through biofortification is a continuum of the soilplant-animal-human pathway. Therefore, equal importance must be placed on understanding micronutrient concentrations in soil, uptake by plants and accumulation in edible plant parts, and their ultimate bioavailability and absorption in the human body for alleviating Zn and Fe deficiencies in human beings. Therefore, the attempts at increasing Zn and Fe in food crops required a broader, comprehensive understanding of the role and behaviour of both these nutrients across the integrated soil, plants and human body matrix.

Materials and Methods

The field experiment was conducted during kharif 2023-24 and 2024-25 at the College Farm, N. M. College of Agriculture, Navsari Agricultural University, Navsari, Gujarat. The experimental soil was clayey in texture, moderately alkaline in reaction and low to medium in available micronutrient status. The experiment was laid out in a Randomized Block Design (RBD) with three replications and fourteen treatments consisting of different combinations of soil and foliar application of iron sulphate (FeSO₄) and zinc sulphate (ZnSO₄) viz., T1: RDF, T2: RDF + soil application of FeSO4 @ 25 kg ha -1 , T3:RDF + soil application of FeSO4 @ 25 kg ha -1 + foliar application of FeSO4 @ 0.5% at tillering and panicle initiation stage, T4: RDF + soil application of FeSO4 @ 50 kg ha -1, T5: RDF + soil application of FeSO4 @ 50 kg ha -1 + foliar application of FeSO4 @ 0.5% at tillering and panicle initiation stage, T6: RDF + soil application of ZnSO4 @ 25 kg ha -1 , T7:RDF + soil application of ZnSO4 @ 25 kg ha -1 + foliar application of ZnSO4 @ 0.5% at tillering and panicle initiation stage, T8: RDF + soil application of ZnSO4 @ 50 kg ha -1 , T9: RDF + soil application of ZnSO4 @ 50 kg ha -1 + foliar application of ZnSO4 @ 0.5% at tillering and panicle initiation stage,T10: RDF + soil application of FeSO4 @ 25 kg ha - 1 + ZnSO4 @ 25 kg ha -1 , T11: RDF + soil application of FeSO4 @ 25 kg ha -1 + ZnSO4 @ 25 kg ha -1 + foliar application of FeSO4 @ 0.5% and ZnSO4 @ 0.5% at tillering and panicle initiation stage,T12: RDF + soil application of FeSO4 @ 50 kg ha -1 + ZnSO4 @ 50 kg ha -1 ,T13: RDF + soil application of FeSO4 @ 50 kg ha -1 + ZnSO4 @ 50 kg ha -1 + foliar application of FeSO4 @ 0.5% and ZnSO4 @ 0.5% at tillering and panicle initiation stage,T14: Control. Finger millet variety GN-8 was used in the study. The recommended dose of fertilizer comprising 40 kg N and 20 kg P₂O₅ ha -1 was applied through conventional fertilizers. Soil application of FeSO₄ and ZnSO₄ was carried out as per treatment at sowing, whereas foliar sprays were imposed at the designated critical growth stages of tillering and panicle initiation. The initial and final soil samples were analysed for available N, P2O5, K2O and micronutrients, viz. Zn and Fe as per the standard procedures. The plant samples of both the grain and straw of finger millet was analysed for both macronutrient and micronutrient uptake. The two years experimental pooled mean data were subjected to statistical analysis as per procedure described by Gomez and Gomez (1984) [4] . Differences among the means and treatments were compared by the least significant difference (LSD) at P≤0.05. [14] and Khobragade et al. (2022) [8] .

Zinc content in grain and straw (%) Zinc concentration in grain and straw responded significantly to agronomic fortification with Fe and Zn, wherein RDF + soil application of FeSO₄ @ 25 kg ha -1 + ZnSO₄ @ 25 kg ha -1 + foliar application of FeSO₄ @ 0.5% and ZnSO₄ @ 0.5% at tillering and panicle initiation stage (T11) registered the highest pooled values (24.69 ppm in grain and 19.38 ppm in straw),it is found to be statistically at par with treatmentT13 (grain) and with treatments T13, T10, T9, T7 and T6 (straw), whereas the absolute control exhibited the lowest value. The simultaneous inclusion of iron may further support metabolic vigor and root activity, facilitating greater zinc mobilization and accumulation in the grain and straw. Such integrated nutrient delivery appears to be highly effective in enhancing zinc loading efficiency and achieving superior agronomic fortification in finger millet. These findings are in agreement with the results of Teklu et al. (2023) [13] , Reddy et al.

(2025) and Waghmare (2025) [15] .

The pooled data in Table 3 revealed that integrated agronomic fortification strategies significantly influenced the total macronutrient uptake of finger millet. The treatment T11 (RDF + soil application of FeSO₄ @ 25 kg ha -1 + ZnSO₄ @ 25 kg ha -1 + foliar application of FeSO₄ @ 0.5% and ZnSO₄ @ 0.5% at tillering and panicle initiation stage) consistently maximized accumulation, yielding the highest total nitrogen (49.50 kg ha -1 ), phosphorus (20.04 kg ha -1 ) and potassium (126.61 kg ha -1 ) uptake. This treatment significantly outperformed the recommended dose of fertilizers alone (T1) and the unfertilized control (T14), which recorded the lowest overall nutrient accumulation. The marked enhancement in total N uptake under T11 is attributed to the synergistic action of zinc and iron, which optimizes root elongation, photosynthetic efficiency, and enzyme activation, thereby accelerating nitrogen translocation into both grain and straw. Continuous nutrient availability throughout the crop cycle favored higher biomass production and a consequently greater removal of nitrogen by the plant, corroborating the findings of Teklu et al. (2023) [13] and Waghmare (2025) [15] . Similarly, the higher total P2O5 uptake under T11 is due to improved phosphorus acquisition and utilization efficiency facilitated by balanced iron and zinc nutrition, which enhanced root growth, rhizosphere nutrient mobilization, and overall dry matter production. Split delivery via soil and foliar modes guaranteed uninterrupted nutrient supply during critical growth stages, promoting greater phosphorus absorption as documented by Shivay et al. (2015) [11] , Roy et al. (2018) [10] and Vijayakumar et al. (2020) [14] . Furthermore, the elevated total K2O uptake under T11 resulted from improved root proliferation, cellular nutrient absorption, and photosynthetic capacity driven by adequate micronutrient supply, which regulates vital metabolic activities and creates favorable cellular gradients for potassium translocation from the soil to the grain and straw. Delivering foliar sprays at tillering and panicle initiation stages ensured timely availability during high-demand growth phases, maximizing potassium utilization. These results are in strong agreement with Shivay et al. (2015) [11] and Dholariya et al. (2020) [2] who reported analogous beneficial impacts of micronutrient applications on macronutrient uptake and overall crop productivity.

Iron and Zinc Uptake

The total iron (Fe) and zinc (Zn) uptake by the grain, straw, and whole crop of finger millet was significantly affected by the various iron and zinc agronomic fortification treatments (Table 4). A critical appraisal of the pooled data revealed that treatment T11 (RDF + soil application of FeSO₄ @ 25 kg ha -1 and ZnSO₄ @ 25 kg ha -1 + foliar application of FeSO₄ @ 0.5% and ZnSO₄ @ 0.5% at the tillering and panicle initiation stage) recorded the highest total Fe uptake (191.31 g ha -1 ) and total Zn uptake (147.69 g ha -1 ). While T11 proved significantly superior to most treatments, it remained statistically at par with T13 regarding both total Fe (185.81 g ha -1 ) and total Zn uptake (141.42 g ha -1 ). These were sequentially followed by treatments T10 and T7 whereas the absolute minimum total Fe (73.01 g ha -1 ) and Zn (49.73 g ha -1 )

uptake values were consistently observed under the unfertilized control (T14). The profound enhancement in micronutrient uptake under T11 can be ascribed to the synergistic advantage of combining basal soil applications with targeted foliar sprays. Soil-applied FeSO4 and ZnSO4 likely enriched the rhizosphere, maintaining a steady baseline availability of Fe and Zn during early vegetative growth to promote robust root proliferation and enhanced nutrient absorption. Concurrently, foliar interventions at critical physiological phases-namely tillering and panicle initiation facilitated rapid, direct nutrient entry through the foliage when crop demand peaks. Because iron is essential for chlorophyll biosynthesis, electron transport, and respiratory metabolism, and zinc plays a key regulatory role in enzyme activation, protein synthesis, and membrane stability, their optimal supply enhanced overall photosynthetic efficiency, assimilate production, and dry matter accumulation. This synchronized source-to-sink translocation resulted in substantially higher micronutrient accumulation in both the grain and straw. These findings align with similar beneficial effects of integrated Fe and Zn fertilization on nutrient uptake and agronomic biofortification reported by Niyigaba et al. (2019) [9] , Jalal et al. (2020) [6] , Vijayakumar et al.

(2020) [14] and Khobragade et al. (2022) [8] .

Conclusion

It can be concluded that for achieving superior grain quality of finger millet cv. GN 8, the crop should be fertilized with RDF (40:20 kg NP ha -1 ) along with soil application of FeSO₄ @ 25 kg ha -1 and ZnSO₄ @ 25 kg ha -1 and two foliar sprays of FeSO₄ 0.5% + ZnSO₄ 0.5% at tillering and panicle initiation stage. Additionally, it also improved nutrient use efficiency and sustained soil fertility under south Gujarat condition.

References

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