REGULATION OF PICEA-ABIES SEED DORMANCY BY RED AND FAR-RED LIGHT AT VARIOUS MOISTURE CONTENTS

The effects of red (R), far-red (FR) and R + FR light on Norway spruce seed dormancy were studied at five different moisture contents (MC) b etween 5 and 20%. The degree of dormancy was studied by germinating se eds over a wide range of temperatures in the dark. The non-irradiated control seeds were shallowly dormant, only a proportion of them germin ated and within a limited temperature range. Red light progressively s timulated germination between 5 and 17% MC, but this effect was revers ed if a FR treatment followed, although all germination could not be i nhibited by one FR pulse. Far-red light had a slightly stimulating eff ect at 19% MC. To generate seeds able to germinate over a wide range o f temperatures in darkness, an artificial light pretreatment should be given to seeds at MC above 17% in order to receive maximum response.