Germination and viability of wild sunflower species seeds stored at room temperature and low humidity for 38 years

Authors: Seiler, Gerald

Submitted to: Seed Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/5/2022
Publication Date: 8/19/2022
Citation: Seiler, G.J. 2022. Germination and viability of wild sunflower species seeds stored at room temperature and low humidity for 38 years. Seed Science and Technology. 50(3):307-315. https://doi.org/10.15258/sst.2022.50.3.01.
DOI: https://doi.org/10.15258/sst.2022.50.3.01

Interpretive Summary: While optimal storage conditions for seeds of wild sunflower species are known, the effects of prolonged storage on germination and viability under less-than-optimal conditions is not known. The objectives of this study were to test the germination of wild annual and prairie sunflower seeds stored at room temperature for 38 years, determine if the seed was still alive or just dormant, and test a plant hormone that might stimulate the dormant seed to germinate. Germination of wild annual sunflower seeds was 5.5%, while prairie sunflower had only 0.75% germination. The germination of fresh seeds at harvest was 35% for wild annual and 18.5% for prairie sunflower. Viability testing indicated that the seeds were alive, but dormant, resulting in very low germination. Pre-treating the stored seeds with a plant hormone increased germination of the wild annual sunflower from 5.5% to 38%, and prairie sunflower from 0.75% to 4.5%. The results of this study will be useful for genebank curation of wild sunflower seeds where the low germination is due to a deep state of dormancy that can be overcome by a chemical treatment, therefore the seed should not be discarded.

Technical Abstract: While optimal seed storage conditions for genebanks preservation have predictable results, the effects of prolonged storage on germination and viability of seeds of sunflower crop wild relatives stored under less-than-optimal conditions is less known. Seed of two wild annual species, H. annuus (common wild sunflower) and annual H. petiolaris (prairie sunflower) were used to study the effects of storage at room temperature (20 to 22°C) and low humidity of ~ 22% on germination and viability of seed stored in the laboratory for 38 years. The efficacy of using gibberellic acid (GA3) as a germination medium to overcome dormancy was also tested. Germination of wild H. annuus seeds stored for 38 years was only 5.5%, while H. petiolaris was only 0.75%, compared to freshly harvested seeds with 34.7% for H. annuus, and 18.5% for H. petiolaris. Stored wild H. annuus seed had a 44.6% positive staining using the tetrazolium viability test, while H. petiolaris had only 5.6%, indicating that the seeds were alive, but dormant. Treating scarified wild seed with 1 mM GA3 for one hour increased germination of the stored wild H. annuus seed from 5.5% to 38.2% and H. petiolaris from 0.75% to 4.5%. This would indicate that the wild sunflower seeds stored at less-than-optimal conditions for long periods are dormant and should not be discarded as dead. This information will be useful for genebank curation of wild sunflower germplasm.