Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 29, 2008
Publication Date: July 1, 2009
Citation: Peel, M., Waldron, B.L., Mott, I.W. 2009. Ploidy Determination and Agronomic Characterization of NPGS Small Burnet Germplasm. Crop Science. 49:1359-1366. Interpretive Summary: Flow cytometery proved to be an effective and efficient means to characterize the ploidy level of the NPGS small burnet germplasm collection. It was shown that tetraploids and octaploids were present in roughly a 2:1 ratio. The NPGS small burnet collection is diverse for an array of agronomically important traits that may prove useful for developing improved cultivars. The forage productivity from early growth in some small burnet accessions can be similar to alfalfa under dryland conditions. Moreover, there is variation in plant structure among the collection, particularly in leafiness. In fact, there is a clear division among materials for leafy versus stemy plant types that would provide unique opportunities for developing breeding populations, particularly as they could be tested for their relative performance in a rangeland situation and nutritional quality. Furthermore, there were highly productive lines among both of these plant types that would be natural choices for parents. However, the division among plant types is compounded by multiple ploidy levels that would also need testing.
Technical Abstract: Small burnet (Sanguisorba minor Scop.) is an evergreen perennial forb readily utilized by livestock and wildlife that is limited in its use by lack of persistence under heavy grazing. Our objective was to characterize all of the available National Plant Germplasm System (NPGS) small burnet germplasm for variation in agronomic characteristics and ploidy level prior to initiating a breeding program. Ploidy level was determined by flow cytometery. Forage yield, flowering date, mortality, growth habit and leafiness were determined at two field locations in Utah. Of the materials tested 68% were tetraploids (2n=4x=28) and 32% octaploids (2n=8x=56). Significant variation was observed for all traits examined (P<0.0001). Mean forage yield of the small burnet was 1.45 Mg ha-1, ranging from not measurable to 2.96 Mg ha-1 compared to 'Ladak' alfalfa (Medicago sativa L.) at 2.28 mg ha-1. Flowering date varied among accessions by 12 d while mortality ranged from zero to 100%. Growth habit ranged from completely prostrate to upright and highly leafy plants to ones with few leaves in all growth habit forms. The range among accessions was similar within the two ploidy levels for all traits except flowering date which was two d earlier in the octaploids. Flow cytometery proved to be an efficient means to determine ploidy level among small burnet germplasm. The forage production of some small burnet accessions can be comparable to alfalfa and phenotypic variation in such that the germplasm has potential for improvement through recurrent selection.