Dormancy and after-ripening response of seeds from natural populations and conserved Physaria (syn. Lesquerella) germplasm and their association with environmental and plant parameters

Seed dormancy studies in Physaria are still limited to date. To further understand this trait as well as the after-ripening response in these new crop taxa, we sampled different seed lots of genebank conserved accessions and natural populations of Physaria fendleri (syn. Lesquerella fendleri) and Physaria gordonii (syn. L. gordonii) in the U.S. Southwest. We subjected seeds from the natural populations to different after-ripening regimens, storing them over two saturated salt solutions (LiCl and MgCl2) to equilibrate seed moisture levels, at three storage temperatures (5, 25, and 35 °C) for various lengths of time (4, 8, and 12 weeks) and then germinated the seeds at different temperatures (constant 24 °C and alternating 15/25 °C), while seeds from the conserved accessions to 4 and 12 weeks storage at MgCl2 and at an alternating 15/25 °C. Results obtained from the populations indicate significant differences for total germination among storage durations and between germination treatments. In contrast, no significant difference in total germination was found for seeds of the conserved accessions between storage durations, even with gibberellic acid supplementation. We further explored possible associations of the observed germination responses to climatic data and other parameters recorded from the natural populations.

► The germination of seeds from wild populations and genebank accessions was analyzed.
► Seeds of genebank accessions have more uniform germination than those from wild.
► After-ripening regimens have more pronounced effects in freshly harvested seeds.
► Correlation of germination to plant sizes and habitat parameters was determined.