Seed oil quality of GA3 induced flowering evening primrose (Oenothera biennis L.).

Gamma-linoleic acid in the seed oil of evening primrose makes it nutritionally and pharmaceutically valuable. If evening primrose wants to be cultivated as an annual plant, sowing time is important. By the late sowing and depends to time most plants do not produce flower stem and stay in rosette stage until next spring. To solve this problem, the present study was performed. Seedling were transplanted to 4 kg plastic pots containing a mixture of leaf compost: local soil: perlite (1:2:1 ratio) and placed in outdoor conditions. Non-vernalized plants were then selected and treated with different temperature regimes (1, 2 and 3 weeks in 4-6ºC) and gibberellic acid (GA3) application in different concentrations of 0, 500, 1000, 2000 ppm, separately. The results showed that although some physiological parameters were affected by low temperature, no flower stem was produced. In contrast, plants that were treated with GA3 produced flower stem. Time of flowering and the number of flowers were significantly affected by the concentrations of applied GA3. Although yield components of GA3 induced plants were higher than that of normal growth plant, the seed yield of them was low. Surprisingly, the gamma linolenic acid (GLA) percentage of seed oil of plants treated with 2000 ppm GA3 was significantly higher than that of non- treated plants. Finally, it can be concluded that, although the application of GA3 guarantees delayed sowing evening primrose flowering and better GLA production, but low seed yield is a subject that cannot be easily ignored in production.