Effect of sulphur fertilisation on yield and quality of white mustard seeds

The objective of the present study was to estimate the effect of different forms of sulphur on yields and qualitative parameters of white mustard seeds. This topic was studied in 2004 in the form of a pot trial in a vegetation hall and linked up with an identical experiment with spring wheat conducted in 2003. Besides the control variant not fertilised with sulphur (1) we fertilised the soil with elemental sulphur (2), ammonium sulphate (3) and gypsum (4) and applied foliar dressing of elemental sulphur with bentonite (5). For all variants the nitrogen dose was 0.9 g per pot (0.15 g . kg−1 of soil) and for va­riants 2 to 4 it was 1 g of sulphur per pot (0.17 g. kg−1 of soil). Foliar dressing of elemental sulphur (S0) was not applied until the stage of six true leaves in a dose of 10 kg per ha (0.032 g per pot).Significantly higher yields of white mustard seeds were achieved after foliar application of S0 which can be also due to its fungicide action. The variants where gypsum was applied showed the highest average number of branches and pods and also straw yields. After gypsum fertilisation or foliar application of S0 the oil content in the mustard seeds exceeded 25%; this is the minimal content required for the production of good quality mustard. The 1000-seed weight was significantly higher after foliar application of S0. The proportion of seeds greyish on the surface, a sign of mildew, significantly decreased after fertilisation with all forms of sulphur, but most of all after foliar application of S0.Fertilisation with ammonium sulphate reduced the exchangeable soil reaction after harvest. On the other hand gypsum alkalised the soil environment and increased the content of available calcium and water-soluble sulphur. The soil of the variant where foliar dressing of S0 was applied had a higher content of available calcium after harvest. The least amount of available sulphur and phosphorus in the soil was seen after foliar application of S0 signalising a more efficient uptake of nutrients from the soil for the production of seed yields and for the quality of the seeds.