Olive Seeds Research Articles

Role of the Endocarp in ‘Manzanillo’ Olive Seed Germination

Abstract The endocarp of ‘Manzanillo’ olive (Olea europaea L.) seeds was subjected to several treatments in order to determine its effect on germination of the olive seed. The endocarp inhibited germination in stratified as well as unstratified olive seeds. Removing the endocarp resulted in high percentages of germination, but only when it was completely removed or when the radicle end was removed. The endocarp did not inhibit germination by preventing imbibition, since water uptake occurred in the seed through the untreated endocarp and through the clipped cotyledon end. The endocarp also did not contain water soluble inhibitors that prevent germination. Rather, the endocarp seemed to inhibit germination through mechanical resistance. High percentages of germination can occur only when the structure of the endocarp is altered, reducing its resistance to embryo expansion.

‘Manzanillo’ Olive Seed Dormancy as Influenced by Exogenous Hormone Application and Endogenous Abscisic Acid Concentration

Abstract Embryo germination of olive (oleo europaea L.) was inhibited by 10 ppm abscisic acid (ABA); no embryo germination effects were found with treatment of gibberellins (GA3 or GA4+7) or 6-benzylamino purine (BA). Whole seed germination was reduced by 100 ppm GA3. Only ABA was found in extracts of olive seed tissues. Young developing embryos contained up to 600 ng/g fresh weight ABA which declined to nondetectable amounts at seed maturity. ABA was not detected in endosperm plus seedcoat until seed maturity, then at 8 ng/g dry weight. In early stratification, no ABA could be detected in any seed tissues. It seemed evident that embryo tissues were more sensitive to ABA as seed maturity approached, and by then seed germination may be prevented by ABA at 8 ng/g dry weight found in endosperm and seedcoat.

Influence of Environment, Seed Tissue, and Seed Maturity on ‘Manzanillo’ Olive Seed Germination

Abstract Harvesting seed of ‘Manzanillo’ olive (oleo europaea L.) at the end of October, when embryo growth was complete, gave optimum germination and extended storage life with lower germination rates and shorter storage life before or after this date. Optimum germination occurred at 15°C for whole seed and 25° for excised embryos; both grew faster at 25° after germination. Seed and excised embryos germinated equally well in light or dark.

Anatomical and Morphological Development of ‘Manzanillo’ Olive Seed in Relation to Germination

Abstract Microscopic examination of sectioned germinating olive seed (Olea europaea L.) did not reveal differences from many other seed types. No seedcoat-imposed mechanical restrictions were found during germination. The seed was 4% and the embryo 1% of the mature, whole fruit dry weight. Maximum embryo dry weight was achieved by early October. Germination was 90% when the embryo had gained 60% of its final dry weight. No dormancy factors were evident in the excised embryos.