Effect of different irrigation regime, chemical, and biological fertilizers, on fatty acids content and oil yield of evening primrose (Oenothera Biennis L.)

To evaluate the effect of different irrigation regime and chemical and biological fertilizers on the fatty acids content and oil yield of evening primrose, a factorial experiment based on randomized complete blocks design with three replications was conducted in the years of 2015-2016. In the main plots, three levels of irrigation regime (irrigation at 30, 40 and 50% of field capacity) and in the factorial sub-plots three levels of chemical fertilizer (no application, 50% and 100% urea + superphosphate combined application Recommended) with four levels of biofertilizers (inoculation and non- inoculation of mycorrhiza and azospirillum). The results of the analysis of variance showed a significant difference between irrigation regimes, chemical fertilizers, biological fertilizers and interaction of irrigation regimes and fertilizer in all studied traits. Drought stress, reduced oil yield per hectare, omega (3, 6, 7 and 9), ratio of total unsaturated fatty acids to saturated fatty acids and total unsaturated fatty acids. But the total saturated fatty acids and all saturated fatty acids increased. The highest levels of gamma-linolenic, linolenic, oleic and vaccinic fatty acids due to irrigation interaction at 40% agronomic capacity and combined application of urea + triple superphosphate fertilizers with 100% recommended in combination with inoculation of mycorrhiza and Azospirilum were achieved. In general, drought stress decreased the amount of unsaturated fatty acids (reduced oil quality) and oil yield, and the use of fertilizers increased the amount of unsaturated fatty acids.