Sunflower grain quality as affected by sulphur added to nitrogen fertilizer under different planting seasons

Abstract

The objective of the study was to investigate the effect of sulphur added to nitrogen fertilizer on sunflower grain quality under different planting seasons. This study was executed in the 2020/21, 2021/22 and 2022/23 planting seasons at Molelwane farm, North-West Province, South Africa. The experiment was a 5x2 factorial fitted into a randomized complete block design (RCBD). Two sunflower cultivars (PAN7057 and AGSUN8251) were planted. The five fertilizer combinations used were 30S kg/ha + 120N kg/ha, 30S kg/ha + 180N kg/ha, 60S kg/ha + 120N kg/ha, 60S kg/ha + 180N kg/ha and a control. The quality parameters measured included oil, protein, crude fibre, starch, and ash content. Planting season had no significant effect (p>0.05) on grain oil content. However, planting season had a significant effect (p<0.05) on grain protein content. Sunflower planted during the first and third planting seasons (2020/21 and 2022/23) produced a significantly higher protein content. Sulphur/nitrogen rate had a significant effect (p<0.05) on sunflower oil and protein content. Sunflower treated with sulphur/nitrogen rates of S30+N180 and S60+N120 kg/ha produced a significantly high oil and protein content. Sunflower treated with sulphur/nitrogen rates of S60+N180 kg/ha also produced a significantly high protein content. The results of this study suggest that variations in climatic conditions during planting seasons affect sunflower quality parameters. A sunflower cultivar PAN7057 showed an increase on the performance in terms of grain quality parameters. In this study, sulphur/nitrogen fertilizer rates of S60+N120 and S60+N180 kg/ha are considered effective in promoting sunflower grain quality performance.