Morphological and physiological variation of plant architecture in red clover (Trifolium pratense)

Grass/clover mixtures contribute to agricultural sustainability by reducing nitrogen fertilization and increasing the nutritional value of feed and food (high protein and polyunsaturated fatty acid levels). However, the current red clover cultivars have a low persistence. Persistence can be improved by altering the plant’s architecture, which is controlled both by genetics and environment. We have analyzed two of the many branching phenotypes, i.e., a highly branched and creeping genotype (Crossway2), and a poorly branching and erect genotype (Diplomat8). The branching was observed in clonal replicates grown in containers during one growing season in two different environments (open air and growth chamber). The number of nodes and the quantity and position of bud outgrowth into branches differed greatly between genotypes. Comparable results were obtained for both environments, which suggests good heritability of branching patterns. We also investigated how the hormones auxin and strigolactone influence branching in the two genotypes. Because of the complexity of a red clover plant (non-outgrowing main axis, many first order branches), we applied these hormones to isolated single node segments. Bud outgrowth was inhibited to the same level in both genotypes after hormone application. In the future, we will study the involvement of strigolactone genes in the branching of red clover. This knowledge, when applied in red clover breeding programmes, may generate plants with added value towards yield and persistence.