THE EFFECT OF LIGHT QUALITY ON THE GERMINATION OF 8 SPECIES FROM SANDY HABITATS IN WESTERN-AUSTRALIA

The impact of darkness and a range of monochromatic light conditions on germination was documented for eight native and naturalised 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 drummondii, also a species of coastal dunes was inhibited under high energy light (430-490 nm) but showed no percentage germination differences in light of wavelengths between 520 and 720 nm and under dark conditions. Asphodelus fistulosus, a species of similar life-form characteristics to Trachyandra divaricata, showed no effect on germination percentage of varying light quality.