Changes in seed yield and oil quality of flax (Linum usitatissimum L.) for industrial use in response to nitrogen and potassium fertilization

The effect of nitrogen (N) and potassium (K) fertilization on yield and oil content in flaxseed, chemical properties and the composition of the fatty acids in the seed oil of flax, is important considering the growing global demand of the oil. The experiment was conducted at Barrackpore, West Bengal, India, with a combination of four N (0, 40, 80 and 120 kg ha(-1)) and three K (0, 30 and 60 kg ha(-1)) doses replicated thrice in a randomised complete block design. The quality of flax seed oil was significantly influenced by N and K fertilization. Higher N doses decreased the seed oil content but increased the oil yield. Increased N doses reduced the iodine value (IV), peroxide value (PV), and unsaturated fatty acid (UFA) content, particularly the alpha-linolenic acid (ALA) content in flax seed oil while the acid value (AV), free fatty acid (FFA), saturated fatty acid (SFA) and oleic acid contents were increased with N application. Potassium fertilization decreased the values of FFA, PV, ALA in flax seed oil and enhanced the oleic acid and poly-unsaturated fatty acid (PUFA) content. The UFA/SFA and oleic acid/ALA ratio decreased at higher N and K doses.