Field study of Texas native evening primrose and evaluation of selected seed treatments
Evening primrose oil has increasingly become of interest to the health care industry for its legitimate effectiveness in treatment of certain pathological conditions. The essential component of evening primrose oil is gamma-linolenic acid (GLA) (018:3 A6, 9,12). Four accessions of Texas native evening primrose containing higher levels of GLA were evaluated for feasibility as a field crop through transplants. Highest seed yields were reported with plant populations of 32.3 thousand plants per hectare. Very little significance was reported in percent oil yield between the three different plant spacings examined. Germination chamber and greenhouse experiments were conducted using KNO3 and PEG 8000 as priming agents at -0.5 and -1.0 MPa for 5-, 10-, and 15-day treatments to overcome dormancy symptoms affecting germination. The most effective treatments for O. elata were achieved with -0.5 MPa osmotic potentials using PEG 8000 for 5 days and -1.0 MPa using PEG 8000 for 5 or 10 days. The best priming treatment for O. jamesii resulted from using PEG 8000 at the -0.5 MPa level for 15 days. The most effective treatment for O. rhombipetala occurred at the 10 and 15 day treatments at the -1.0 MPa osmotic potential. Red light treatments showed no significant differences for the species O. rhombipetala. O. elata showed the test results using a germination chamber regardless of the light treatment.