%0 Article
%T Effect of photon flux density on bud dormancy release in Norway spruce seedlings.
%A Höyhtyä, Riitta
%A Hänninen, Heikki
%D 1991
%J Silva Fennica
%V 25
%N 3
%R doi:10.14214/sf.a15610
%U https://silvafennica.fi/article/5452
%X <p>The effect of photon flux density on bud dormancy release in two-year-old seedlings of Norway spruce (<em>Picea abies</em> (L.) H. Karst.) was examined. The seedlings were first chilled for 0–21 weeks under natural conditions and then forced in a warm greenhouse either in low (15 μEm<sup>-2</sup>s<sup>-1</sup>) or in high (300 μEm<sup>-2</sup>s<sup>-1</sup>) photon flux density. Occurrence of bud burst was observed in the forcing conditions, and the observations were used for estimating the cumulative frequency distribution of the chilling requirement for growth competence. The estimated distribution had greater variance in the low photon flux density than in the high photon flux density forcing. This finding suggests that unnaturally low photon flux densities during forcing may yield overestimates of the genetic within-population variation in the chilling requirement for growth competence.</p>
<p>The PDF includes an abstract in Finnish.</p>