The effects of light temperature and osmotic stress on the germination of pinus halepensis and pinus brutia seeds
Thanos, C.A.; Skordilis, A.
Seed Science and Technology 15(1): 163-174
1987
ISSN/ISBN: 0251-0952
Accession: 006664956
Seeds of the mediterranean pines, Pinus halepensis and P. brutia, germinate optimally at 20.degree. C in darkness. Their temperature range of germination is rather narrow and their rate very slow. When seeds are osmotically stressed the rate becomes even slower, while final germination percentage is inhibited only at very low osmotic potentials. Continuous red light or diurnal white light always promote germination rate and sometimes maximum percentage, as well. Intermittent far-red light not only inhibits germination in both species, but also induces a secondary dormancy, shown to be under phytochrome control. Experiments under daily alternating conditions of light and temperature resembling those which are naturally met, lead to the conclusion that field germination is feasible throughout the rainy season of the mediterranean-type climate and is strongly favoured in open, sunny sites.