The effect of sowing date and sowing density on the yield and quality of crambe seeds. A case study in north-eastern Poland

The present study was undertaken to determine the effect of sowing date and sowing density on stand architecture, yield components, seed yields, and seed quality in crambe (Crambe abyssinica Hochst. ex R.E. Fries) grown in north-eastern Poland in 2020-2022. The experiment had a split-plot design with four sowing dates (early: 30 March-1 April; and delayed by 7, 14, and 21 days) and five sowing densities (150, 200, 250, 300 and 350 live hulled seeds m-2). Crambe seed yields were determined by growing degree days (GDD) during the entire growing season (positive correlation), and by precipitation during flowering (positive correlation) and ripening (negative correlation). Higher values of GDD during the growing season and lower precipitation levels during ripening increased the crude fat (CF) content and decreased the total protein (TP) content of crambe seeds. Higher values of GDD during flowering contributed to the accumulation of crude fiber (CFR) in crambe seeds. Sowing date was a key factor influencing seed yields and crop quality because it affected GDD and precipitation distribution in each growth stage. The yield of hulled seeds was highest (2.17-2.23 Mg ha-1) when crambe was sown early at a density of 200-250 live hulled seeds m-2. When sowing was delayed by 21 days, the CF and CFR content of crambe seeds decreased by 6% and 17%, respectively, whereas their TP content increased by 7%. An increase in sowing density to 350 hulled seeds m-2 increased the CF and CFR content of seeds by 8% and 7%, respectively. Abyssinian oil contained 82-85% of MUFAs (including 63-65% of C22:1), 13-15% of PUFAs, and 2-3% of SFAs. The content of C20:1 increased and the content of C22:1 decreased when crambe was sown with a 21-day delay.