Effect of nitrogen and sulphur levels on yeild, nutrient content and uptake of mustard

Introduction

Mustard (Brassica juncea), commonly known as Sarson or Rai, is an important rabi oilseed crop in India, cultivated on nearly 6.86 million hectares. It plays a vital role in diverse cropping systems, often grown after rice, maize, pearl millet, urad bean, groundnut, and sunflower in different states. Mustard seeds contain about 37-49% oil, and with low production costs and high yield potential, the crop holds considerable promise for large-scale cultivation in the country. Nitrogen (N) is essential for rapid growth, higher productivity, and improved quality in mustard. It plays a critical role in the synthesis of plant proteins and chlorophyll and is required in greater amounts compared to other macronutrients. Being a mobile nutrient, nitrogen is transported from older to younger leaves, hence deficiency symptoms appear first on older foliage. Nitrogen deficiency results in thin, open canopies, shortened flowering duration, reduced pod set, and ultimately lower yield. Sulphur (S) is recognized as the fourth major nutrient for oilseed crops due to its significance in growth, development, and oil synthesis (Patel et al., 2024). It is involved in several physiological and metabolic functions, including enzyme activation, chlorophyll formation, and glucosinolate synthesis in mustard. Sulphur application also improves yield attributes, oil content, fatty acid composition, and glucosinolate levels. Ray and Sengupta (2012) reported that sulphur uptake was significantly higher (18.1 kg ha⁻¹) with 60 kg S ha⁻¹ application, which was statistically comparable to 45 kg S ha⁻¹ (17.47 kg ha⁻¹).

Materials and Methods

A field experiment was conducted during the rabi season of 2024-25 at the AICRP on Mustard research farm, College of Agriculture, Nagpur (Maharashtra). The site experiences a subtropical climate with dry conditions for most of the year and an average annual rainfall of 1064.1 mm. The mean annual temperature is 25.9°C, with seasonal variations: maximum temperature averages 33.7°C in kharif (June-Sept), 27.5°C in rabi (Oct-Jan), and 38.8°C in summer (Feb-May). May is typically the hottest month, with temperatures rising above 45°C for 5-10 days. Minimum temperatures range from 8°C to 30.8°C, and relative humidity varies between 26.4% and 94.1%. Before laying out the experiment, five soil samples were collected randomly from a 0-15 cm depth for chemical analysis. The soil at the site was clayey in texture, moderately alkaline (pH 7.93), and contained available nutrients: N (253.28 kg ha⁻¹), P (18.42 kg ha⁻¹), K (344.00 kg ha⁻¹), S (9.51 mg kg⁻¹), along with soil organic carbon (5.21 g kg⁻¹).

The experiment was laid out in a factorial randomized block design (FRBD) with three replications, comprising 9 treatment combinations of nitrogen (50, 65, and 80 kg N ha⁻¹) and sulphur (15, 30, and 45 kg S ha⁻¹). Each plot measured 18 m² (4.5 × 4.0 m), making a total of 27 plots. Data were analyzed statistically following the methods of Gomez and Gomez (1984), and treatment means were compared at a 5% level of significance using critical difference (C.D.). Relevant results were presented graphically.

Results and Discussion

Effect of nitrogen and sulphur on yield of mustard An examination of data in Table 1. on seed yield, stover yield of mustard.

The maximum seed yield of mustard (18.25 q ha⁻¹) was obtained with the application of 80 kg N ha⁻¹, which was statistically at par with 65 kg N ha⁻¹ (17.84 q ha⁻¹). A significant increase in seed yield was observed with increasing nitrogen levels, confirming that mustard responds positively to higher nitrogen supply. These findings are in line with the results of Neha et al. (2014) [15] , who also reported enhanced seed and stover yield, growth attributes, and yield parameters with higher nitrogen application. Sulphur application also showed a significant effect on seed yield. The highest yield (18.02 q ha⁻¹) was recorded with 45 kg S ha⁻¹, which was significantly superior to 15 kg S ha⁻¹ (17.06 q ha⁻¹) and statistically comparable with 30 kg S ha⁻¹ (17.67 q ha⁻¹). The interaction between nitrogen and sulphur levels was significant, and the combined application of 80 kg N ha⁻¹ and 45 kg S ha⁻¹ produced the highest seed yield. Similar results were reported by Tetarwal et al. (2013) [12] , who found that seed and stover yields increased significantly up to 30 kg S ha⁻¹, and Solanki et al. (2015), who observed substantial improvement in seed yield with sulphur application, with maximum yields achieved at 50 kg S ha⁻¹.

Stover Yield (q ha -1 ) Stover yield was significantly influenced by nitrogen levels. The highest stover yield (53.47 q ha⁻¹) was obtained with 80 kg N ha⁻¹, which was significantly superior to 50 kg N ha⁻¹ (48.78 q ha⁻¹) and statistically at par with 65 kg N ha⁻¹ (52.28 q ha⁻¹). This indicates that higher nitrogen application significantly increases straw yield over lower levels. Similar observations were reported by Kapur et al. (2010) [3] , who noted significantly higher yields with 60 kg S ha⁻¹, though these were at par with 45 and 30 kg S ha⁻¹ in terms of the number of primary and secondary branches per plant. Sulphur fertilization also contributed significantly to stover yield. The highest stover yield was obtained with 45 kg S ha⁻¹, which was statistically comparable with 30 and 60 kg S ha⁻¹. The interaction between nitrogen and sulphur was found to be significant. Raman and Trivedi (2012) [8] similarly reported that seed and stover yields of mustard increased significantly with each successive increment in sulphur application. They observed that sulphur application at 20, 40, and 60 kg ha⁻¹ increased seed yield by 13.9%, 28.1%, and 28.6%, respectively, over the control, averaged over two years. Effect of nitrogen and sulphur on content of mustard Data presented in Table 2 revealed that the highest concentrations of N (4.07% in seed and 0.75% in stover), P (0.67% and 0.36%), K (0.79% and 0.60%), and S (0.62% and 0.26%) were recorded under the N₃ treatment (80 kg N ha⁻¹), followed closely by 65 kg N ha⁻¹. The improvement in nutrient content with higher nitrogen application may be attributed to its vital role in rapid growth, higher productivity, and quality enhancement in mustard. Nitrogen is fundamental for protein and chlorophyll synthesis and is required in greater quantities than other macronutrients.

Being mobile within the plant, nitrogen is translocated from older to younger leaves, hence deficiency symptoms first appear in older foliage. Similar findings were reported by Hossain et al. (2012) [2] , who observed that N, P, K, and S concentrations in seeds increased with higher nitrogen levels, with maximum N content (3.6%) recorded at 150 kg N ha⁻¹.

Sulphur application also had a significant impact on nutrient content. The highest values of N (4.06% in seed and 0.73% in stover), P (0.66% and 0.35%), K (0.76% and 0.59%), and S (0.60% and 0.26%) were observed in the S₃ treatment (45 kg S ha⁻¹), followed by 30 kg S ha⁻¹. The growing importance of sulphur fertilization in improving yield and quality of Indian mustard is now well recognized. Mustard has a comparatively higher sulphur requirement for optimum growth, development, and oil synthesis. Neha et al. (2014) [5] also reported that application of 60 kg S ha⁻¹ significantly increased sulphur concentration in both seed and stover, while 40 kg S ha⁻¹ improved sulphur content by 13.6% and 38.2% over 20 kg S ha⁻¹ and control, respectively. However, further increase in sulphur beyond this level was found to be statistically at par. [4] also reported that nitrogen application significantly enhanced seed and biological yields up to 100 kg N ha⁻¹, with the highest total N uptake (82.4 and 79.3 kg ha⁻¹) recorded at 100 kg N ha⁻¹, while uptake declined with reduced N levels.

Sulphur fertilization also had a significant influence on nutrient uptake. The highest values of N (73.61 and 37.66 kg ha⁻¹), P (12.09 and 18.44 kg ha⁻¹), K (14.05 and 30.58 kg ha⁻¹), and S (10.74 and 12.22 kg ha⁻¹) were observed in the S₃ treatment (45 kg S ha⁻¹), followed by 30 kg S ha⁻¹. These findings are in agreement with Panchal et al. (2011) [6] , who demonstrated that seed, protein, and oil yields of mustard increased significantly with nitrogen and sulphur application, both individually and in combination, across two years of experimentation. They further noted that nutrient uptake, particularly N and S, showed significant improvement up to 100 kg N and 40 kg S ha⁻¹ compared to the control.

Conclusion

It is concluded that application of 80 kg ha -1 N and 45 kg ha - 1 S is best treatment followed by 65 kg ha -1 N and 30 kg ha -1 S treatment combination for getting sustainable yield, content and uptake of mustard.

References

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