Effect of different levels of sulphur and zinc on growth, yield and quality of Indian mustard (Brassica juncea L.)

Introduction

Indian mustard (Brassica juncea L.) belongs to the family Brassicaceae and commonly called as Rai. It contains good amount of oil usually 30-38%. India is having 6.23 million ha area under rapeseed-mustard and 9.34 million tonnes production with average productivity of 1499 kg ha -1 , which is about three-fourth of the world's average productivity (1960 kg ha -1 ) (DAC and FW, 2020) [3] . Rajasthan having first position in terms of area and production accounting for 2.37 m ha and 4.08 Mt followed by Uttar Pradesh with around 0.75 m ha and 1.12 Mt out of the total rapeseed mustard area and production respectively. In UP Mathura district has the highest area, production and productivity which is 0.053 Mha, 0.077 Mt and 1453 kg ha -1 respectively" (Directorate of economics and statistics, 2020-21 [4] (DAC and FW). Indian mustard is a coolseason crop that grows in both tropical and temperate climates. It thrives in cooler temperatures and requires a dry period for harvesting. In India, it is primarily cultivated during the Rabi (winter) season, from September-October to February-March. Indian mustard can tolerate annual rainfall ranging from 50 to 420 cm, temperatures between 6 °C and 27 °C, and a pH range of 4.3 to 8.3. While it grows best in neutral pH soil (7), it can also adapt to alkaline and slightly saline soils, as well as temperatures between 15°C and 20 °C. With its efficient photosynthetic response through the C3 pathway, rapeseed-mustard thrives in well-drained, non-waterlogged soils. It can grow in various soil types, from sandy loam to clay loam, but performs best in light loam soils. Due to its relatively low water requirements (24-40 cm), it is well-suited for rainfed cropping systems. It requires temperature between 06 o -26 o C. It is generally grown in rainfed condition. It requires well drained soil and is moderately tolerant to acidic soil. Water requirement of mustard is low (240-400 mm) which is sufficient for rainfed cropping system. Oil content in mustard varies from 37% to 49% with 14-15% carbohydrate, 25-30% protein, 10-12% fibre, 1 1.5% minerals and vitamins, 2-3% glucosinolate. Mustard oil contains about per kg of sulphur applied (Katyal et al., 1997) [8] . Zinc is a vital micronutrient essential for the growth, development, and metabolism of mustard crops, playing a key role in enzyme activation, hormone regulation, and several physiological processes (Sharma and Singh, 2015) [16] . It is crucial in photosynthesis, protein synthesis, seed formation, and early plant development, particularly by promoting root growth and seed germination, which directly influence plant establishment and productivity. Zinc deficiency in mustard leads to stunted growth, chlorosis (yellowing of leaves), poor flowering, and reduced seed yield, severely impacting both the quality and quantity of the harvest. Application of zinc fertilizers in Indian mustard has been shown to increase yield by 11 to 40% (Sinha et al., 2000) [18] .Zinc is a component of many enzymes involved in various metabolic activities and regulates growth hormones such as Indole-3-acetic acid (IAA) and Auxin. It enhances pod setting, seed formation, and oil synthesis, thereby increasing both biological seed and stover yield. Zinc also stabilizes cytoplasmic ribosomes, supports cell division, activates enzymes like dehydrogenase and proteinases, and promotes starch formation, seed maturation, protein synthesis, and carotene production (Mandal et al., 2002) [11] .Regions with alkaline or calcareous soils often experience low zinc availability, making mustard crops more vulnerable to deficiency symptoms like poor root development and low resistance to environmental stresses and pests (Singh et al., 2019; Das et al., 2020) [19,5] . Recent studies emphasize the importance of zinc supplementation in improving mustard crop performance under varied soil conditions (Kumar et al., 2017; Sharma et al., 2020) [10,17] . In Uttar Pradesh, widespread micronutrient deficiencies, aggravated by intensive cropping and high-yielding varieties, result in poor vegetative growth, flower and fruit drop, and low seed production. Among micronutrients, sulphur and zinc are most critical for oilseed crops' growth and development (Verma et al., 2023) [21] . Thus, adequate zinc management is indispensable for enhancing mustard crop productivity and quality, especially in zinc-deficient soils.

Materials and Methods

The field experiment was carried out at the Crop Research Farm of United University, U.P India during rabi season of the year 2024-2025 Prayagraj is located at 25.45 o N and 81.84 o E in the southern part of Uttar Pradesh at an elevation of 98 meters (322 ft).The soil of the experimental field was silty loam in texture and slightly alkaline in reaction with P H , 7.2, EC 0.20 dsm - 1 organic carbon 0.40%and available Nitrogen 196 kg ha - 1 Phosphorus18.9 kg ha -1 and potassium 260.50 kg ha -1 at 0-15 cm soil depth. The experiment was laid out in factorial randomized block design with 16 treatment each replicated thrice. The study was carried of two factor viz. sulphur and zinc with four dose of sulphur and zinc viz. 0, 15, 35, 55 kg ha -1 and 0, 5, 10, 15 kg ha -1 respectively were applied basal dose. The sowing was done on the 23 October 2024. The crop was sown by using 3.5 to 5 kg ha -1 and recommended fertilizer was applied 120kg N, 60kg P 2 O 5 40kg K 2 O ha -1 uniformly in all plots as a feeder dose and plantb protection measure vwere spraying malathion 50EC @1 liter dissolved in 1000liters of water ha -1 for the control of hairy cattterpiller. Spraying of Imidachloroprid 17.8 EC @ 375 ml in 1000 liters of water ha-1 was applied as per requirement for the control of aphids. The crop was harvested manually at the maturity dated on 1 march 2024 and seed and stover were recorded.

Results and Discussion

3.1 Effect of sulphur and zinc on growth attribute of Indian mustard 3.1.1 Plant Population (plants/m 2 ) At both the initial and final stages of crop growth, sulphur and zinc application significantly influenced plant population. The highest plant population was consistently observed with 55 kg/ha sulphur (S3), recording 24.58 plants/m² initially and 28.42 plants/m² at the final stage. Zinc application at 15 kg/ha (Z3) also resulted in higher populations, with 21.08 plants/m² initially and 25.42 plants/m² at the final stage. The lowest populations were seen in control treatments without sulphur (S0) and zinc (Z0). Notably, the interaction of 55 kg/ha sulphur and 15 kg/ha zinc (S3Z3) produced the highest overall plant population-28.33 plants/m² initially and 32.33 plants/m² at the final stage. In contrast, the S0Z0 treatment (no sulphur or zinc) had the lowest plant population at both stages, with 8.33 and 10.67 plants/m² respectively. These results highlight the positive effect of sulphur and zinc, individually and in combination, on crop stand establishment and growth.

Biological yield

The highest biological yield per plot (9.10 kg) was recorded with 55 kg/ha sulphur (S3), followed by 8.34 kg at 35 kg/ha (S2), while the lowest yield (5.74 kg) was observed in the control (S0). For zinc, 15 kg/ha (Z3) produced the maximum biological yield (8.45 kg), followed by 7.75 kg at 10 kg/ha (Z2), with the minimum (6.12 kg) in the control (Z0). The combined application of sulphur and zinc showed that S3Z3 yielded the highest biological output (9.70 kg), followed by S3Z2 with 8.34 kg, while the lowest (5.20 kg) was found in the untreated control S0Z0.

Phosphorus uptake

Phosphorus uptake in mustard seeds and stover significantly increased with higher zinc and sulphur treatments. In seeds, the highest phosphorus uptake (19.20 kg/ha) occurred under S3 (55 kg/ha zinc), followed by S2 (35 kg/ha) with 17.34 kg/ha, while the control S0 registered the lowest at 13.16 kg/ha. Among zinc levels, Z3 (15 kg/ha) showed the greatest uptake (17.35 kg/ha), followed closely by Z2 (16.98 kg/ha), with the minimum (11.41 kg/ha) under Z0 (0 kg/ha). The interaction of both nutrients further enhanced uptake-S3Z3 (55 kg/ha zinc + 15 kg/ha zinc) produced the maximum seed phosphorus uptake of 21.35 kg/ha, closely followed by S3Z2 at 19.87 kg/ha. The lowest value, 11.41 kg/ha, was recorded in S0Z0.In stover, phosphorus uptake peaked at 20.41 kg/ha under S3 and 19.20 kg/ha under Z3, with the lowest values in S0 (14.47 kg/ha) and Z0 (15.15 kg/ha). The S3Z3 combination again achieved the highest uptake at 23.90 kg/ha, followed by 21.24 kg/ha in S3Z2, while S0Z0 recorded the minimumof11.94 kg/ha.

Potassium uptake

Potassium uptake in mustard seeds and stover significantly improved with the application of sulphur and zinc at varying levels. In seeds, the highest potassium uptake (13.64 kg/ha) was observed under S3 (55 kg/ha sulphur), followed by S2 (12.23 kg/ha), while the lowest (10.84 kg/ha) was noted in the control (S0). Among zinc treatments, Z3 (15 kg/ha) led to the highest uptake (12.76 kg/ha), followed by Z2 (12.30 kg/ha), and the lowest was in Z0 (11.06 kg/ha). The interaction of both nutrients showed that the S3Z3 combination resulted in the maximum uptake (15.23

Zinc uptake

Zinc uptake in mustard seeds and stover improved significantly with the application of sulphur and zinc. In seeds, the highest zinc uptake (111.69 g/ha) was recorded under S3 (55 kg/ha sulphur), followed by S2 (100.77 g/ha), while the lowest (66.10 g/ha) was in S0 (0 kg/ha). Among zinc levels, Z3 (15 kg/ha zinc) led to the highest uptake (106.96 g/ha), followed by Z2 (102.46 g/ha), with the lowest in Z0 (53.88 g/ha). The interaction treatment S3Z3 (55 kg/ha sulphur + 15 kg/ha zinc) gave the maximum seed zinc uptake (135.77 g/ha), and S0Z0 had the least (55.15 g/ha).In stover, zinc uptake was also highest with S3 (162.88 g/ha) and Z3 (158.15 g/ha), while the lowest uptake was under S0 (117.28 g/ha) and Z0 (105.06 g/ha). The combined treatment S3Z3 recorded the highest zinc uptake (186.96 g/ha), followed by S3Z2 (182.73 g/ha), while the lowest uptake (106.34 g/ha) was observed in the control (S0Z0).

Economic parameters 3.4.1 Cost of cultivation

Maximum cost of cultivation was recorded in treatment S 3 Z 3 (Sulphur 55 kg/ha + Zinc 15 kg/ha) with Rs 1,01,105 ha -1 followed by S 3 Z 2 (Sulphur 55 kg/ha + Zinc 10 kg/ha) with Rs 99,805 ha -1 and the minimum (Rs 89,505 ha -1 ) was recorded in treatment S 0 Z 0 (Sulphur 0 kg/ha + Zinc 0 kg/ha).

Gross return

Maximum gross returns were recorded in treatment S 3 Z 3 (Sulphur 55 kg/ha + Zinc 15 kg/ha) with (Rs 2,04,621 ha -1 ) followed by S 3 Z 2 (Sulphur 55 kg/ha + Zinc 10 kg/ha) with (Rs 94,898 ha -1 ) and the minimum (Rs 1,12,146 ha -1 ) was recorded in treatment S 0 Z 0 (Sulphur 0 kg/ha + Zinc 0 kg/ha).

Net Return

Maximum net returns were recorded in treatment S 3 Z 3 (Sulphur 55 kg/ha + Zinc 15 kg/ha) with (Rs 1,03,516 ha -1 ) followed by S 3 Z 2 (Sulphur 55 kg/ha + Zinc 10 kg/ha) with (Rs 95,093 ha -1 ) and the minimum (Rs 22,641 ha -1 ) was recorded in treatment S 0 Z 0 (Sulphur 0 kg/ha + Zinc 0 kg/ha).

Benefits cost ratio

Maximum benefit cost ratio was recorded in treatment S 3 Z 3 (Sulphur 55 kg/ha + Zinc 15 kg/ha) with 2.02 ha -1 followed by S 3 Z 2 (Sulphur 55 kg/ha + Zinc 10 kg/ha) with 1.95 ha -1 and the minimum (1.25 ha -1 ) was recorded in treatment S 0 Z 0 (Sulphur 0 kg/ha + Zinc 0 kg/ha).

Conclusion

The combined application of sulphur at 55 kg/ha and zinc at 15 kg/ha (S3Z3) was the most effective treatment for enhancing mustard crop performance. This treatment resulted in the maximum plant height of 165.47 cm, significantly higher than all other treatments, due to sulphur and zinc promoting meristematic activity and cell elongation for vigorous growth.

The highest number of branches per plant (9.62) was also recorded under S3Z3, indicating improved plant structure and photosynthetic capacity. Additionally, S3Z3 produced the greatest number of siliquae per plant (356.83), contributing to better reproductive success. Seed yield peaked at 24.38 q/ha with S3Z3, showcasing the synergistic effect of sulphur and zinc in nutrient use efficiency and assimilate partitioning. The harvest index was highest (35.42%), reflecting improved biomass conversion into economic yield. The treatment also recorded the highest oil content at 41.27%, highlighting sulphur's role in oil biosynthesis and zinc's role in enzyme activation during lipid metabolism. Economically, S3Z3 provided the highest gross returns (Rs 2,04,621/ha) and the best benefit-cost ratio, emphasizing its profitability. Overall, the S3Z3 treatment significantly enhanced mustard growth, yield, quality, and economic returns, underscoring the importance of balanced sulphur and zinc nutrition for optimal crop production.

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