Dependency of seed dormancy types on embryo traits and environmental conditions in R ibes species

The hypothesis that seed dormancy may be dependent on environmental conditions and seed morphological traits was tested for six R ibes species, across an altitudinal gradient of 1300 m and a longitudinal separation of 120°. Embryo measurements and seed germination experiments were conducted for R . alpinum L., R . hudsonianum Richardson var. petiolare ( D ouglas) J ancz., R . nevadaense K ellogg, R . roezlii R egel var . cruentum ( G reene) R ehder and R . speciosum P ursh, and data taken from the literature for R . multiflorum Kit . ex S chult. ssp . sandalioticum A rrigoni. Germination was compared with seed viability to reveal proportional seed dormancy, which was then correlated to seed/embryo morphological traits and these traits related to the seed provenance environment. The embryos of all the investigated species are linear underdeveloped and all had a morphological component of seed dormancy ( MD ). Seeds of R . roezlii , R . hudsonianum and R . nevadaense required a temperature and/or hormone pre‐treatment in order to germinate, highlighting morphophysiological seed dormancy ( MPD ). Seed dormancy was found to be strongly negatively correlated with embryo length, but not with embryo to seed (E:S) ratio or seed mass. Initial embryo length was positively related to mean annual temperature. Seed dormancy in the investigated R ibes species could be quantified and predicted by the interaction of embryo traits and environmental conditions. This approach may be helpful in assessing and predicting seed dormancy in the R ibes genus and in other genera and families with underdeveloped embryos.