Effects of light and temperature on seed germination of Poa pratensis from high latitudes.

摘要

One- to three-year-old seed of Poa pratensis ecotypes Lavang, Leikra and Ryss was germinated under various temperature and light regimes on a thermogradient plate and on paper or in soil in phytotron compartments. These seed batches had differing origins in respect to altitude and latitude. While the optimal constant temperature for germination of Lavang and Leikra in 12 h light/12 h dark cycles was around 16鳦, Ryss germinated nearly 100% over the 10-28鳦 temperature range. Compared with constanttemperatures, daily fluctuations, even at the small amplitude 18/15鳦, stimulated germination of Lavang and Leikra. Dark germination was inferior to germination in light/dark cycles at constant temperatures of 15鳦 and higher, but light showed no advantage at alternating temperature. Continuous light inhibited germination regardless of light source (fluorescent, incandescent or natural). The stimulating effect of daily light/dark cycles increased, but the inhibiting effect of continuous light decreasedwith increasing seed age. It is concluded that seed of Poa pratensis ought to be covered by a 0.5-1.0 cm soil layer when sown in a northern environment involving continuous light and low soil temperatures.