Author
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Qu, Luping |
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Widrlechner, Mark |
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Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 8/18/2011 Publication Date: 9/25/2011 Citation: Qu, L., Widrlechner, M.P. 2011. Reduction of seed dormancy in Echinacea pallida (Nutt.) Nutt. by in-dark seed selection and breeding. Industrial Crops and Products. 36(1):88-93. Interpretive Summary: Strong seed dormancy has been an obstacle for field production of purple coneflower (Echinacea) species. Other researchers have typically focused on time-consuming and labor-intensive seed-treatment methods to overcome this problem. Such methods are incompatible with organic production if synthetic chemicals are used (and users of dietary supplements strongly prefer organic production). We attempted to use genetics to reduce seed dormancy through selection and plant breeding, by using pale purple coneflower (E. pallida) as a model species. We used three different germplasm collections (accessions) in our study. Nine parent plants of each accession, selected from early, in-dark germinated seeds (in-dark plants) or from late, in-light seeds (in-light plants), were grouped by accession and germination treatment method and planted for seed production. Germination tests indicated that our in-dark plants produced seeds (in-dark seed) with much less seed dormancy than those from our in-light plants (in-light seed). The in-dark seeds germinated at much higher rates than did the in-light seeds, more than 2× at 25 degrees C under light, up to 83× more in darkness, and up to an 8× increase over corresponding parental seed lots under comparable germination conditions. Beyond the germination increase, in-dark seeds showed early and synchronized germination as compared to the in-light seeds. Since our results were acheived from only one selection cycle, they strongly suggest that we have developed a very effective method to modify seed dormancy in Echinacea through repeated selection cycles. Our approach can now be used by plant breeders to develop new Echinacea cultivars that can reduce production costs and create new opportunities for growers of medicinal plants. Technical Abstract: Strong seed dormancy has been an obstacle for field production of Echinacea species. Previous research on overcoming Echinacea seed dormancy has been extensive and focused on treatment methods, which involve time and expense, and are incompatible with organic production if synthetic chemicals are used. We have attempted to genetically reduce seed dormancy through selection and breeding in Echinacea, by using E. pallida as a model species. Three accessions were used in this study. Nine parent plants of each accession selected from early, in-dark germinated seeds (in-dark plants) or from late, in-light seeds (in-light plants) were planted and grouped by accession and germination treatment method for seed production through a polycross method. Germination tests indicated that these in-dark plants produced seed (in-dark seed) with significantly reduced seed dormancy when tested under light or dark conditions in comparison to the seed of the in-light plants (in-light seed). Among the three accessions, the in-dark seed germinated at much higher rates than did the in-light seed, more than 2× at 25 degrees C under light and up to an 83× increase in darkness, and up to an 8× increase over the corresponding parental seed lots under comparable germination conditions. In addition to these increases in germination, the in-dark seed showed early and synchronized germination as compared to the in-light seed. Since these results were achieved through only one cycle of selection and breeding, they strongly suggest that we have developed a very effective method for modifying seed dormancy in Echinacea. |
