The incidence, field performance and heritability of non-dormant seeds in white clover (Trifolium repens L.)

• Published in: Seed science research Vol. 20; no. 3; pp. 169 - 177
• Main Authors: D'hondt, Bram, Brys, Rein, Hoffmann, Maurice
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.09.2010
• Subjects: clonal repeatability; dormancy breaking; Fabaceae; filling period; flowering; forage legumes; genetic variation; genotype; genotype by environment; germination; Greenhouses; hardseededness; heritability; Humidity; incidence; inflorescences; permeability; phenotypic plasticity; plant ecology; plant establishment; plant growth; plant reproduction; relative humidity; seed dormancy; seed germination; Seeds; softseededness; testa; Trifolium repens; water impermeability; wild plants; germination; hardseededness; clonal repeatability; softseededness; genotype by environment; water impermeability; Fabaceae
• ISSN: 0960-2585; 1475-2735
• DOI: 10.1017/S0960258510000152

Mature seeds of many legume species are normally characterized by water-impermeable seed coats, a form of physical dormancy. However, observations have suggested that the incidence of mature but permeable (non-dormant) seeds is sometimes substantial. Yet, the ecological processes associated with this non-dormancy have received little attention by plant ecologists. In white clover (Trifolium repens), we therefore studied: (1) the occurrence of initially permeable seeds in wild populations; (2) the relative performance of non-dormant and dormant seeds in plant establishment and reproduction in a field-sown experiment; and (3) the extent to which the trait is affected by humidity and plant genotype in a greenhouse experiment. No less than 35% of all viable seeds from the wild populations proved to be water permeable at maturity. The proportion of permeable seeds within inflorescences ranged from 0 to 100%. In the field-sown experiment, autumn-germinated non-dormant seeds had almost equally good chances of establishing as spring-germinated dormant seeds. Due to a marked head start in growth, the former yielded more flowers (and thus seeds) in the first flowering season. However, the greenhouse experiment proved that variation in the proportion of permeable seed between inflorescences represented a plastic response to humidity conditions during seed ripening, rather than variation among clones (broad-sense heritability ≤ 0.025). Thus the trait is not easily subject to selection.