Role of 'Underdeveloped' Embryos in Germination / Dormancy Problems
Changes in embryo development in germinating seeds of Melianthus major (Melianthaceae)
Morphological (MD) and morpho-physiological (MPD) dormancy are an endogenous type of seed dormancy described for seeds including those with underdeveloped or undifferentiated embryos. Seeds with such embryos have been observed in 55 plant families. Morphologically dormant species can take 30 days to germinate, whereas morpho-physiologically dormant species will take 30 days before radicle protrusion.
The optimal germination conditions are unknown for many collections from plant families believed to exhibit MD or MPD. Furthermore, analyses of successful MSB germination tests show that 335 collections currently held take 56 days to germinate and therefore may be described as having MPD.
This project aims to investigate the pattern of embryo development and the phenology of germination and emergence in species thought to have MPD, using a combination of laboratory and field-based experiments. Families of particular interest include the Ranunculaceae and Amaryllidaceae. Studies into the germination requirements of European species in both families have shown that embryo growth occurs during the summer with germination following in cooler autumn temperatures. Seemless embryo growth following natural dispersal in Anemone species and Fritillaria tuberosa suggests that embryos in these species should not be defined as dormant.
Key papers published since 2006:
Ali, N.S., Probert, R.J., Hay, F.R., Davies, H. & Stuppy, W. (2007). Post-dispersal embryo growth and acquisition of desiccation tolerance in Anemone nemorosa L. seeds. Seed Science Research 17(3): 155-165.
Mondoni, A., Probert, R., Rossi, G., Hay, F. & Bonomi, C. (2008). Habitat-correlated seed germination behaviour in populations of wood anemone (Anemone nemorosa L.) from Northern Italy. Seed Science Research 18(4): 213-222.
Mondoni, A., Probert, R., Rossi, G. & Hay, F. (2009). Germination phenology of the woodland geophyte Anemone ranunculoides L. (Ranunculaceae) from northern Italy. Seed Science Research 19: 137-144.
Carraso, V., Hay, F.R., Probert, R.J. & Mucciarelli, M. (2011). Temperature control of seed germination in Fritillaria tubiformis subsp. moggridgei (Liliaceae) a rare endemic of the South-west Alps. Seed Science Research 21(1): 33-38.
Newton, R.J. (2011). Development, Dormancy, Germination and Ex-situ Survival of Seeds of Selected Amaryllidaceae Species. PhD Thesis, University of Reading, Reading, UK.