Comparative Study of Alfalfa and Medicago truncatula Stem Traits: Morphology, Chemical Composition, and Ruminal Digestibility

• Published in: Crop science Vol. 47; no. 4; pp. 1672 - 1680
• Main Authors: Schnurr, J.A, Jung, H.J.G, Samac, D.A
• Format: Journal Article
• Language: English
• Published: Madison, WI Crop Science Society of America 01.07.2007; American Society of Agronomy
• Subjects: Agronomy. Soil science and plant productions; Alfalfa; Biological and medical sciences; carbohydrate content; Carbohydrates; cell wall components; Chemical composition; chemical constituents of plants; Chemicals; Comparative studies; digestibility; Economic impact; forage composition; forage crops; forage legumes; forage quality; Fundamental and applied biological sciences. Psychology; Genetic engineering; Genetics and breeding of economic plants; Grasses; Growth chambers; inbred lines; Light microscopy; lignin; Medicago sativa; Medicago truncatula; plant age; plant morphology; polysaccharides; protein content; Proteins; rumen fermentation; Saccharides; species differences; Stem cells; stems; Tissues; Medicago truncatula; Interspecific comparison; Medicago sativa; Rumen; Cell wall; Stem; Leguminosae; Dicotyledones; Morphology; Angiospermae; Spermatophyta; Chemical composition; Fodder crop; Lucerne; Comparative study; Digestibility
• ISSN: 0011-183X; 1435-0653
• DOI: 10.2135/cropsci2006.12.0762

Alfalfa (Medicago sativa L.) is an agronomically important forage, but digestibility of stem cell wall material is low. Because the tetraploid genome of alfalfa complicates genetic dissection of complex pathways, the diploid M. truncatula Gaertn. could serve as a model for stem cell wall development in alfalfa. We compared stem morphology, chemical composition (protein, soluble carbohydrates, cell wall polysaccharides, and lignin), and in vitro ruminal cell wall polysaccharide digestibility of two alfalfa clones (Regen-SY27 and 718) and four M. truncatula inbred lines (A17, A20, DZA315.16, and R108) in a replicated growth chamber experiment. Stem tissue development and cell wall lignification observed by light microscopy were similar between the species. While differences in stem morphology, composition, and digestibility were observed among the germplasms, there was overlap between the alfalfa and M. truncatula germplasms for all traits except protein concentration, which was greater for the two alfalfa clones. Younger stem internodes (top third of the stem) of both species had a higher protein concentration and greater cell wall polysaccharide digestibility, and lower cell wall concentration than older internodes (bottom third of stem). Based on the data presented here, it appears that M. truncatula is a suitable model for stem development, composition, and digestibility of alfalfa.