Seed germination behavior of five Resedaceae species from arid Arabian desert: gibberellic acid and light effects

Abstract

Light and growth-promoting compounds, such as gibberellic acids (GA₃), are among the most important factors that can break physiological seed dormancy. Here, we investigate the effects of GA₃ and light on germination of five species of Resedaceae that are known to have different levels of physiological dormancy. Seeds were incubated at 20/30 °C in both 12-hr photoperiod and complete darkness. To study the effect of growth hormone on germination, seeds were soaked for 24 h in different concentrations of GA₃ before sowing. The annuals (Reseda aucheri and Oligomeris linifolia) and the perennial Ochradenus arabicus had deep physiological dormancy, and exogenous application of GA₃ enhanced their germination in the light, but not in darkness; few or no seeds germinated in the dark in these species. Ochradenus aucheri and O. baccatus had intermediate and non-deep dormancy, respectively, and application of GA₃ enhanced their germination in both light and darkness. Germination of the annual species was much slower than that of the shrubby perennials. Overall, these results indicate that conditions under which seed developed, matured and stored on maternal plants as well as incubation conditions should be taken into consideration when assessing germination behavior of the perennial species of Resedaceae.

Keywords:

• Germination
• photoblastism
• dormancy
• seed bank
• seed size
• Arabian deserts

Acknowledgements

The authors thank Prof Amr Abdel-Hamid, Director General of Sharjah Research Academy for encouragement and support. The editor of Plant Biosystems and two anonymous reviewers are gratefully acknowledged for their useful comments and suggestions to improve the manuscript.

Disclosure statement

The authors declare no conflict of interest.