Can water limitation and seed pretreatment change leaves and inflorescences secondary metabolites and fatty acid composition of grain oil in borage (Borago officinalis L.)?

Abstract

ABSTRACT Two field experiments were conducted to investigate the effects of irrigation intervals (normal irrigation and mild, moderate and severe water deficit) and seed pretreatments (non-priming, and seed priming with water, KNO3 and KH2PO4) on secondary metabolites of borage in two consecutive years. Changes in grain and oil yields as well as fatty acid profile of borage in response to water limitation were also evaluated in the second year. Saponin, tannin and mucilage contents of borage leaves and saponin content of inflorescence were significantly enhanced under moderate and severe water limitations. Seed pretreatment with KNO3 and KH2PO4 increased the saponin content of borage under stress in the first year and in the second year, KH2PO4 improved tannin content of leaves. Leaf mucilage content under severe stress tended to be higher due to seed priming (although it was not confirmed statistically). Water supply had no significant effect on oil percentage of grains, but grain yield decreased under severe water deficit which led to a significant reduction in the oil yield of borage. The linoleic and gamma-linolenic acids content and oleic/linoleic ratio under different irrigation treatments were statistically similar. However, percentages of palmitic and oleic acids were markedly higher under severe stress.