Effect of sulphur and potassium on yield, nutrient uptake and quality characteristics of mustard (Brassica juncea L.) in udic haplustepts of Kanpur

Field experiment conducted on mustard crop (Varuna) with four levels each of S (0, 20, 40 and 60 kg S ha⁻¹) and K (0, 30, 60 and 90 kg K₂O ha⁻¹) on Udic Haplustepts during rabi seasons of 1998–99 and 1999–2000 showed that mustard crop responded significantly to the application of S and K. The seed and stover yields increased in the linear order up to 40 kg S and 60 kg K₂O ha⁻¹. The highest seed yield (2035 kg ha⁻¹) at 40 kg S ha⁻¹ was 27.59 per cent higher in comparison to the yield at control. Similarly, application of 60 kg K₂O ha⁻¹ produced highest seed yield (2085 kg ha⁻¹) which was 35.48% higher in comparison to the yield in control. Sulphur showed synergistic relationship with potassium. The uptake of N, K and S at maturity was significantly affected with treatments. The P uptake significantly increased up to 40 kg S ha⁻¹ and thereafter, decreased significantly. Per cent utilization of added K and S was maximum when lowest levels of K and S were applied. Oil, protein and total S-amino acid contents increased significantly with the application of S and K. Sulphur and K addition also influenced remarkably the fatty acids composition; oleic and linoleic acid contents increased and erucic acid decreased showing improved quality of mustard oil.