Performance of lucerne genotypes for biomass production and nitrogen content differs in monoculture and in mixture with grasses and is partly predicted from traits recorded on isolated plants
2017
Maamouri, Amel | Louarn, Gaëtan | Béguier, Vincent | Julier, Bernadette | Unité de Recherche Pluridisciplinaire Prairies et Plantes Fourragères (P3F) ; Institut National de la Recherche Agronomique (INRA) | Jouffray-Drillaud | Thèse en cofinancement Inra - région Poitou-Charentes
Grass–legume mixtures are key crops to improve agricultural sustainability. Despite their significant use inmixture, lucerne (Medicago sativa L.) varieties are mostly tested and bred for monocultures. This study was performed toevaluate whether the ranking of lucerne genotypes for biomass components and quality was similar in monoculture andmixture, and whether traits recorded on isolated plants could help to predict performance in monoculture and mixture. For46 genotypes planted in the three competition conditions, plant biomass, shoot height, shoot number and protein contentwere recorded. In addition, maximum leaf size, internode length, stem diameter, growth habit, specific leaf area and leafdry-matter content were measured on isolated plants. A general positive correlation was observed between the performanceof genotypes in monoculture and in mixture. However, significant changes in genotype ranking indicated that the speciesof its neighbours could modify the relative performance of a genotype. The traits that minimised competition intensityalso changed according to the neighbour species. In mixture, competition intensity was highest for plants with longinternodes, a high shoot number and a non-erect growth habit. In monoculture, plants with long internodes and largesleaves suffered less from competition. The agronomic performance of lucerne varieties differing in their architectureshould be compared in monoculture and mixture to finally identify the traits to be phenotyped to improve lucerne varietyperformance in both cultivation modes.
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