TEMPERATURE EFFECTS ON FATTY-ACID COMPOSITION DEVELOPMENT OF LOW-LINOLENIC OILSEED RAPE (BRASSICA-NAPUS L.)

The influence of temperature during seed development on the fatty acid composition of oilseed rape (Brassica napus L.) was studied in one lo w-linolenic and one conventional canola cultivar. The cultivar Regent produces seed oil with similar to 20% linoleic acid (C18:2) and simila r to 8% linolenic acid (C18:3), whereas Stellar is relatively high in C18:2 (similar to 25%) and low in C18:3 (similar to 2.5%). Both cultiv ars were grown in the field, and the fatty acid compositions of the se ed oils were monitored throughout the period of seed development. In t he field, the content of saturated (C16:0 + C18:0) and monounsaturated (C18:1) fatty acids in the seed oil increased when seed developed und er high temperatures. C18:3 levels were higher in seed harvested at si tes with lower average daily temperatures. The low C18:3 trait of the cultivar Stellar was relatively stable over environments. Both tempera ture and duration of exposure to the temperature during seed developme nt affected the fatty acid composition of the seed in a controlled env ironment study. Plants subjected to a high-temperature treatment (30/2 5 degrees C day/night) for 40 d produced seed with the lowest C18:3 co ntent and the highest levels of C16:0 + C18:0 and C18:1. This was obse rved in both cultivars.