Temperature effects on fatty acid composition during development of low‐linolenic oilseed rape (<i>Brassica napus</i> L.)

Abstract The influence of temperature during seed development on the fatty acid composition of oilseed rape ( Brassica napus L.) was studied in one low‐linolenic and one conventional canola cultivar. The cultivar Regent produces seed oil with ∼20% linoleic acid (C18:2) and ∼8% linolenic acid (C18:3), whereas Stellar is relatively high in C18:2 (∼25%) and low in C18:3 (∼2.5%). Both cultivars were grown in the field, and the fatty acid compositions of the seed oils were monitored throughout the period of seed development. In the field, the content of saturated (C16:0+C18:0) and monounsaturated (C18:1) fatty acids in the seed oil increased when seed developed under high temperatures. C18:3 levels were higher in seed harvested at sites with lower average daily temperatures. The low C18:3 trait of the cultivar Stellar was relatively stable over environments. Both temperature and duration of exposure to the temperature during seed development affected the fatty acid composition of the seed in a controlled environment study. Plants subjected to a high‐temperature treatment (30/25°C day/night) for 40 d produced seed with the lowest C18:3 content and the highest levels of C16:0+C18:0 and C18:1. This was observed in both cultivars.