Yield Components and Fatty Acids Variation of Canola Cultivars Under Different Irrigation Regimes and Planting Dates

To investigate the effect of different planting dates and irrigation regimes on six canola cultivars, a 2-year (2014–2016) experiment was conducted at the Seed and Plant Improvement Institute of Karaj. The experiments were conducted as the factorial split-plot in a randomized complete block design including six canola cultivars (Gabriella, Brutus, Triangle, Marathon, Danube, and Natali), two irrigation regimes (fully irrigated and irrigation termination at the flowering stage) and two planting dates (October 1 and November 1). The results showed that irrigation termination from the flowering stage prevented the supply of required material for filling the seeds and the metabolism of the seed compounds and reduced the growth period of the seed. Therefore, a reduction was observed in the content of oleic and linoleic acids and proline. Also, water deficit stress caused an increase in the glucosinolate content of the seed. The response of canola cultivars was different in terms of fatty acids, so that the Natali cultivar had higher palmitic, oleic acids, and proline content compared to the other cultivars at both planting dates. Fully irrigated treatment and planting date of October 1 produced the highest amount of seed and oil yield (4659 and 2073 kg ha⁻¹), palmitic acid (5.5%), and proline (22.7 μmol/g) content, and the lowest glucosinolate content (13.2 mg/g). Generally, the Natali cultivar and planting date of October 1 and the fully irrigated regime are highly recommended in the studied area regarding qualitative traits and yield of canola.