effect of foliar application of plant extracts on the growth behavior and quality of evening primrose (oenothera biennis l.)

The indeterminate behavior of evening primrose is a frequent limitation in its cultivation. controlling the final growth of plants at a certain stage is important. in the present ‎experiment, different plant extracts were compared functionally with ‎cycocel at different times of application. the experiment was performed as a factorial experiment based on a ‎randomized complete block design with three replications. treatments included normal water ‎‎(control), cycocel (zero and 100 ppm), walnut (juglans regia l.) leaf extract (zero and 25%), oak ‎fruit extract (quercus castaneifolia l.) (zero and 25%), and cotton ‎capsule extract (gossypium hirsutum l.) (zero and 25%). evaluations were made on the seeds, oil yield and yield-components. the foliar application significantly reduced stem length (43-80%) and plant height (13-‎‎33%), but increased the percentage of oils (18.75%) and free fatty acids (67.5%). the highest ‎oil content (35%) occurred in response to a combination of walnut, oak, cotton extracts, and cycocel.‎‏ ‏the highest amount of free fatty acids (23%) indicated more immature‏ ‏seeds and ‎was obtained under the treatment of cotton extract. natural extracts increased the oil percentage, but reduced ‎the free fatty acid percentage and the stem length. it seems that further studies in this ‎regard can help control non-terminal growth of evening primrose without having a need for breeding ‎programs.