Submitted to: Trifolium Conference Abstract & Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/16/2008
Publication Date: 6/1/2008
Citation: Papadopoulos, Y.A., Michaud, R., Bertrand, A., Coulman, B., Acharya, S.N., Bittman, S., Riday, H., Viands, D., Boe, A., Mcrae, K., Castonguay, Y. 2008. Response to selection under controlled environment versus natural selection in diverse regions across Canada. Trifolium Conference Abstract & Proceedings. Available://www.naaic.org/Meetings/National/2008meeting/proceedings/proceedings2008.htm
Technical Abstract: Red clover is a widely adaptable and productive forage legume species found in most temperate regions of the world. To date, specific selection techniques for identifying genotypes with superior persistence have not been successful in improving the general adaptation and the long-term persistence of this species. A new method of selection has been developed which uses freezing stresses under environmentally-controlled conditions to selectively eliminate less cold tolerant genotypes. This study which is a component of the NE1010 Regional Cooperative Research project, a USA/Canada initiative, seeks to develop new red clover germplasm with improved adaptation to diverse regions. The specific objective of this investigation is to compare the effectiveness of selection using the new controlled environment technique with a traditional phenotypic selection technique, currently used by most red clover breeders. An experimental synthetic, CRS15, was selected as the starting population for the above two methods because it has low invasion of Pratylenchus penetrans but it lacks other general adaptation attributes. In phase I of this study two selection procedures were employed using six sets of 1000 plants from CRS15. The first method (phenotypic selection) consisted of selecting the top 10% plants based on their superior performance during the first three years following transplanting in 5 locations across Canada (Charlottetown, PE; Saint-Foy, PQ; Saskatoon, SK ; Lethbridge, AB; Agaziz, BC). The selected plants from each location were used to produce 5 distinct experimental synthetics. The second method (freezing tolerance) consisted of selecting the top 10% plants having the greatest freezing tolerance following multiple freezing stresses under environmentally-controlled conditions. Seeds from the above new six synthetics, the original seed population and appropriate check cultivars were established at eight locations in the temperate zone of North America in the spring of 2005, to assess the performance of the newly selected populations under solid stand conditions. In addition to the above listed Canadian locations, the evaluation sites included Ithaca, NY, Madison, WI and Brookings, SD. In the establishment and two post-establishment years, entries were harvested whenever 50% of the plots reach 10% flowering stage. Persistence and herbage yield were recorded to estimate selection gain. This report presents the selection gain following one cycle of selection for each of the above selection methods. The analysis across locations showed that differences among sites (S), cultivars (Cv) and S by Cv interactions were highly significant, but differences among methods were non-significant. Even though selection gains when considering both selection methods were not significant, improvement in persistence was observed with only one cycle of selection. An examination of yield data indicated that the highest yielding of the new experimental synthetics at each location was always the one developed at that location.