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.

Keywords:

• rapeseed
• sulfur
• fertilizer application
• growth
• yield

ACKNOWLEDGMENTS

Financial grants received from the Department of Science and Technology (under SERC Fast Track Young Scientist Scheme) and the Council of Scientific and Industrial Research (EMR) by Altaf Ahmad and Ishrat Khan, respectively, are gratefully acknowledged.