Development of cold tolerance in white clover (Trifolium repens L.) in relation to carbohydrate and free amino acid content

carbohidratos carbohydrates cold contenido de materia seca dry matter content durcissement endurecimiento frio froid frost gel genotipos genotypes glucide hardening helada noruega norway procedencia prolina proline provenance resistencia a la temperatura seasonal variation temperature resistance trifolium repens