Effect of Timing of Sulfur Fertilizer Application on Growth and Yield of Rapeseed

Abstract

There is usually a positive yield response when sulfur (S) is applied to rapeseed (Brassica rapa L.) plants grown on S-deficient soils. Recommendations include application of some of or the entire amount of S at planting, but the plant requirement as well as availability of S to rapeseed during its various phenological stages is not well documented. In a field trial, 40 kg S ha⁻¹ was applied as gypsum (CaSO₄·2H₂O) at planting (T₁), during vegetative (T₂, 30 days after sowing), flowering (T₃, 50 days after sowing), and pod-filling (T₄, 65 days after sowing) stages, and in split doses (T₅). Biomass accumulation, leaf-area index, and leaf photosynthetic rate were studied at various growth stages. Seed S (sulfate and organic S) and yield parameters were studied at harvest. Sulfur (40 kg S ha^{− 1}) applied in three split doses during different growth stages caused maximum increase in these parameters, followed by T₂ and T₁. However, no significant discernable difference was observed for the application at planting (T₁) and during vegetative stage (T₂). No significant response was seen following the application of T₃ and T₄ when compared with the control (T₀). On the basis of these results, we concluded that application of S fertilizer in split doses during growth stages is better than application of the entire amount of S at any stage for obtaining optimum yield of rapeseed.