The Effect of Light Quality on the Germination of Eight Species From Sandy Habitats in Western Australia.

Abstract

The impacts of darkness and a range of monochromatic light conditions on germination was documented for eight native and naturalized species growing in sandy habitats in Western Australia. Four lake-margin species, Juncus articulatus, J. microcephalus, J. pallidus and Isolepis prolifera, germinated under red (c. 520-640 nm) light, but remained dormant in the dark or when illuminated with far-red (720 nm) or blue (430-490 nm) light. Sunlight-stimulated germination could be beneficial to these very small seeded species, which may not have sufficient reserves for seedlings to establish following deep burial. Oenothera stricta, a short-lived ruderal species, was also stimulated by red light, a response possibly related to germination following disturbance of overlying vegetation. Trachyandra divaricata, a dune inhabiting species, was inhibited by red light. Inhibition by the wavelengths of light dominant in full sunlight was thought to be a response beneficial to species of blowing sand habitats where germination on the dry surface could prove detrimental. Oenothera drummorndii , also a species of coastal dunes was inhibited under high energy light (430-490 nm) but showed no percentage gemination differences in light of wavelengths between 520 and 720 nm and under dark conditions. Asphodelus fistulosus, a species of similar life-fonn characteristics to Trachyarndra divaricata, showed no effect on germination percentage of varying light quality.