Genetic control of quality traits of lucerne (Medicago sativa L.)

Abstract

An important objective in lucerne breeding is the improvement of feeding value. An understanding of the inheritance of digestibility and cell wall related traits would facilitate the breeding of varieties with higher feeding value. The aim of this experiment was first to determine the genetic control of dry matter digestibility and related biochemical and morphological traits, and to assess phenotypic and genetic correlations between these traits. Quantitative genetic parameters were estimated for enzymatic solubility, neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL), protein content, plant height, and leaf-to-stem ratio. A 7 × 7 diallel design with reciprocals and without selfing among parents from different populations and a 7 × 7 factorial design within the ‘Flamande’ population were studied. In the diallel study, effects due to general combining ability (GCA) were higher than those due to specific combining ability (SCA) for all characters tested. In the factorial study, the F1 progeny effect was significant for all characters. The male effect was highly significant for all traits and higher than the female effect except for plant height. The additive variance was higher than the dominance variance for all characters except for plant height. The inheritance was predominantly additive. The highest narrowsense heritabilities were found for NDF and ADF and leaf-to-stem ratio. As a consequence, NDF or ADF would be more efficient selection criteria than enzymatic solubility in a breeding program for improved feeding value. In both mating designs, NDF, ADF, and ADL were positively correlated with one another and negatively with enzymatic solubility and protein content.