THE EFFECTS OF LIGHT QUALITY AND COLD TREATMENT ON THE PROPAGATION OF HYACINTH BULBS

A major problem with the "scooping" technique for the propagation of hyacinth is that the young bulbs remain dormant after planting. We studied whether light quality in the propagation room and/or low temperature after planting could enhance the number of non-dormant bulbs (cv. Viking). Light treatment had no effect on the number of newly formed bulbs. The appearance of these bulblets, however, was markedly affected by the light treatment. Under blue light the bulbs were smaller but more differentiated than in darkness. Pigmentation (anthocyanin and chlorophyll) was also enhanced by blue light. Under red light some differentiation occurred, but without pigmentation. The light treatments effectively prevented the young bulbs from becoming dormant, as appeared from the number of emerged leaves. This effect was saturated at a fluence rate of 5 μE.m^-2.s^-1, irrespective of light quality. The cold treatment accelerated leaf emergence, but no time was gained if the moment of planting was taken into account. The positive effect of the light treatment on the number of leaves could even be observed with the bulbs that were planted outdoors (after a natural cold treatment of several months). A positive correlation was found between the number of leaves emerged and the yield of new bulbs after the growing season. Consequently a 30–45% increase in yield was accomplished by the light treatment.