Effect of Sowing Date and Glycinebetaine on Seed Yield, Oil Content, and Fatty Acids in Rapeseed Cultivars

This study primarily aimed to identify and suggest appropriate rapeseed cultivars and their optimum sowing time. A factorial split-plot experiment was conducted in a complete randomized block design with three replications during two years (2014-2016). The study was carried out using six rapeseed cultivars, namely, Elvis, HL2012, L155, KR2, HW113 and Danob, three sowing dates (October 7, 17, and 27), and two concentrations of glycinebetaine (0 as control and 0.2%). The sowing dates and the GlycineBetaine (GB) were allotted to main plots and the six cultivars were allotted to subplots. The HL2012 cultivar had the highest seed yield (4,584 kg ha-1), seed oil content (44.6%) and seed oil yield (2,060 kg ha-1), which were achieved optimally in the first sowing date. Application of GB increased the average seed yield from 4,089 to 4,419 (kg ha-1), seed oil from 44 to 44.4% and seed oil yield from 1,818 to 1,976 (kg/ha). The amounts of proline and soluble carbohydrates in the plants increased from the first to the third sowing dates. The early sowing date and the application of GB had positive effects on the quantity and quality of rapeseed oil. The results of cluster analysis showed that three of the six cultivars could be suitable for cultivation in Karaj, Iran.