Effect of Foliar Application of Micronutrient Grade II on Yield and Micronutrient Uptake of Mustard (Brassica juncea L.) in Vertisol

Introduction

Indian mustard (Brassica juncea L.) is an important rabi oilseed crop and a major contributor to edible oil production in India. Sustained crop production under intensive cultivation depends not only on adequate macronutrient supply but also on maintaining an appropriate balance of micronutrients. Iron (Fe), manganese (Mn), zinc (Zn) and copper (Cu) participate in enzyme activity, photosynthesis, chlorophyll formation, redox reactions and other metabolic processes that influence plant growth and reproductive development. Deficiency of these elements can therefore restrict biomass production, nutrient accumulation and yield. Vertisols occupy a large area of central India and are characterized by high clay content and substantial moisture-holding capacity. At the same time, relatively high soil reaction and carbonate-associated fixation can reduce the availability of several micronutrients. The experimental soil in the present study was slightly alkaline, with an initial pH of 7.48. Under such conditions, foliar nutrition provides a direct route for supplying nutrients to the crop during periods of high demand. The Grade II formulation evaluated in the experiment supplied Fe, Zn, B, Mn, Cu and Mo simultaneously. Previous studies have reported that, micronutrient management can improve nutrient accumulation and productivity of mustard. Bhadauria et al. (2012) [1] reported increased micronutrient uptake with micronutrient application, while Jat et al. (2013) [5] observed improved Fe and Zn uptake under combined application of FYM and mineral nutrients. Dhaliwal et al. (2021) further showed that, foliar application of Fe, Zn and N enhanced Fe and Zn uptake in Indian mustard. Sharma et al. (2023) [7] . also reported greater seed concentrations of Fe, Mn, Zn and Cu with foliar nano-nutrient application. Although individual micronutrient applications have been studied extensively, information on a combined Grade II foliar formulation under Vertisol conditions is comparatively limited. Therefore, the present investigation was undertaken to determine the response of mustard to different concentrations and spray frequencies of Grade II, with emphasis on seed and stover yield and the concentration and uptake of Fe, Mn, Zn and Cu.

Materials and Methods

Experimental site and design

The experiment was conducted during the rabi season of 2025-26 at the Research Farm, AICRP Mustard, College of Agriculture, Nagpur, Maharashtra. Mustard variety PDKV-Kartik was used. The experiment was laid out in a randomized block design with seven treatments and four replications. The crop was sown on 13 November 2025 at 45 cm × 10 cm spacing with a seed rate of 5 kg ha⁻¹. The gross plot size was 7.2 × 6.0 m 2 and the net plot size was 6.3 × 5.4 m 2 .

Treatments and foliar application

The recommended fertilizer dose was 50:40:0 N:P₂O₅: K₂O kg ha⁻¹. Grade II contained Fe 2.5%, Zn 3.0%, B 0.5%, Mn 1.0%, Cu 1.0% and Mo 0.1%. One foliar spray was applied at 45 days after sowing (DAS), whereas two sprays were applied at 45 and 65 DAS. The treatment details are presented in table 1.

Table 1: Treatments details

Treatments

Treatment details T1 Absolute control T2 RDF + ZnSO4 + FeSO4 + borax each @ 2 gm L -1 (Farmers practice) T3 RDF + Two foliar spray of micronutrient grade II @ 5 ml L -1 T4 RDF + Two foliar spray of micronutrient grade II @7.5 ml L -1 T5 RDF + Two foliar spray of micronutrient grade II @ 10 ml L -1 T6 RDF + One foliar spray of micronutrient grade II @ 12.5 ml L -1 T7 RDF + One foliar spray of micronutrient grade II @ 15 ml L -1 Note: RDF-50:40:0 NPK kg ha -1 Plant sampling and micronutrient analysis Plant samples representing seed and stover were collected treatment-wise. Samples were washed with tap water followed by deionized water to remove adhering soil, ovendried at 50-60°C, ground and stored in clean polyethylene pouches. A di-acid digest was prepared using nitric acid and perchloric acid in a 9:4 ratio. Concentrations of Fe, Mn, Zn and Cu were determined from the digest using an atomic absorption spectrophotometer following Isaac and Kerber (1971) [4] . Micronutrient uptake was calculated from the respective nutrient concentration and dry matter yield, and the total uptake was obtained by adding seed and stover uptake.

Yield measurement and statistical analysis

Seed yield was determined after drying and weighing the harvested produce and expressed in q ha -1 . Stover yield was determined after drying the harvested stalks and converting plot yield to kg ha⁻¹ or q ha⁻¹. The experimental data were statistically analysed according to the procedures described by Gomez and Gomez (1984) [3] . Treatment means were compared using the critical difference at the 5% probability level.

Results and Discussion

Seed and stover yield Foliar application of Grade II affected mustard productivity, with the response varying according to concentration and spray frequency. The data presented is table 2 indicated seed yield ranged from 11.25 to 14.43 q ha⁻¹, whereas stover yield ranged from 34.26 to 40.39 q ha⁻¹. Treatment T5, consisting of RDF with two sprays of Grade II at 10 ml L⁻¹, produced the maximum seed yield (14.43 q ha⁻¹) and stover yield (40.39 q ha⁻¹). The absolute control (T1) recorded the minimum seed yield (11.25 q ha⁻¹) and stover yield (34.26 q ha⁻¹). Thus, T5 improved seed yield by 28.3% over the absolute control. The response suggests that supplying a balanced mixture of micronutrients through foliage at flowering and siliqua formation supported crop growth and reproductive development. The superior performance of T5 is consistent with the nutrient-uptake response presented below. Laishram and jaswal. (2023) [6] obtained the highest mustard yield of 2867.83 kg ha -1 with RDF + 1% urea foliar spray + 0.5% ZnSO4 + 0.5% FeSO4 at 45 DAS. [5] also reported that, the highest Fe uptake in stover (868.5 g ha -1 ) under 10 t FYM + 40 kg S + 25 kg ZnSO4 + 50 kg FeSO4 ha -1 (2023) [7] reported the highest seed concentrations of Fe (124.12 mg kg -1 ), Mn (91.96 mg kg -1 ), Zn (59.22 mg kg -1 ) and Cu (12.86 mg kg -1 ) under 100% NPK + Zn with two foliar sprays of nano-N and nano-Zn at 30 and 45 DAS.

Table 4: Effect of foliar application of micronutrient grade II on content (mg kg -1 ), uptake (g ha -1 ) and total uptake (g ha -1 ) of micronutrient Mn by mustard

Treatments

Mn content (mg kg -1 ) Mn uptake (g ha -1 ) Total Mn uptake (g ha [1] also reported enhanced micronutrient uptake in mustard following micronutrient application.

Conclusion

Foliar application of micronutrient Grade II improved mustard yield and micronutrient accumulation under the experimental conditions. Among the treatments, RDF (50:40:0 NPK) + two foliar sprays of Grade II at 10 ml L⁻¹ (T5) recorded the highest seed yield (14.43 q ha⁻¹), stover yield (40.39 q ha -1 ) and maximum total uptake of Fe (5141.75 g ha⁻¹), Mn (2803.70 g ha⁻¹), Zn (1778.33 g ha⁻¹) and Cu (601.41 g ha⁻¹). The results indicated that appropriately timed foliar application of micronutrients improved micronutrient acquisition and productivity of mustard.

References

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3. Gomez KA, Gomez AA. Statistical procedures for agricultural research. 2nd ed. New York: John Wiley and Sons; 1984. p. 680.
4. Isaac RA, Kerber JD. Atomic absorption and flame photometry: techniques and uses in soil, plant and water analysis. In: Walsh LM, editor. Instrumental methods for analysis of soil and plant tissues. Madison (WI): Soil Science Society of America; 1971. p. 17-37.
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