RESEARCH TO DEVELOP STRATEGIES AND TECHNOLOGIES FOR PRESERVING PLANT GENETIC DIVERSITY IN EX SITU GENEBANKS
Location: Plant Germplasm Preservation Research Unit
Title: Effects of after-ripening and storage regimes on seed germination behavior of seven species of Physaria germplasm
Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 28, 2011
Publication Date: N/A
Interpretive Summary: Dormancy-breaking protocols for seed germination are lacking for many new crop species and their distant-related relatives that are now being conserved in genebanks. Previously suggested protocols for some of these species need to be tested. A new oilseed crop called lesquerella had improved total germination when a seed treatment using gibberellic acid was applied in addition to light. The study also determined that afterripened seeds exhibit improvement in germination compared to those kept for a shorter time before planting. Results of the study provides information about lesquerella seed behavior when subjected to the different treatments and of interest to genebank curators and researchers especially those working on this crop.
The after-ripening response has been well documented in many plant species but studies of this topic are lacking in many new oilseed crops such as Physaria. In a factorial experiment, we tested the effect of different after-ripening periods and germination conditions on freshly harvested seeds of seven Physaria species, P. argyraea, P. fendleri, P. gracilis, P. rectipes, P. recurvata , P. sessilis, and P. thamnophila. The seeds were stored for 4 and 12 weeks over two saturated salt solutions (LiCl and MgCl2) to equilibrate seed moisture at three storage temperatures (5, 25, and 35oC). We likewise tested a dormancy-breaking protocol on these species by using conditions previously recommended for use in genebanks for P. fendleri. The germination tests were conducted with light (1,052 lux) and gibberellic acid (GA3) (100 ppm) and without them. Results suggested that conditions previously set for P. fendleri are also adequate for P. gracilis, P. recurvata, and P. sessilis, but may still be not optimal for the perennial species, P. argyraea, P. thamnophila, and P. rectipes. Overall, higher germination percentages were obtained with light and GA3 treatments. In all species, we observed slight differences between total germination results after 4 weeks and 12 weeks of storage, with higher values evident only in P. fendleri, P. recurvata, and P. thamnophila after their fresh seeds were subjected to 12 weeks of after-ripening at warm temperatures.