Differences in dormancy release and flowering responses to chilling in freesia corms and cormlets

Imamura, Y. . Coll. of Agriculture; Doi, M.; Imanishi, H.

Differences in dormancy release and flowering responses to chilling in freesia corms and cormlets

1996

Imamura, Y. (Osaka Prefectural Univ., Sakai (Japan). Coll. of Agriculture) | Doi, M. | Imanishi, H.

Cote d'Azur freesia corms heavier than 3g sprouted earlier than did lighter corms kept in moist rock wool medium at 25 degrees C; this temperature is effective for breaking dormancy and shoot growth. Cormlets sprouted after the corm to which they were attached. The days to sprouting were reciprocally correlated to cormlet weights; the relationship is represented by the equation: y = 9.49/x + 106.01 (r=0.82, significant at P=0.01), where y=days to sprouting and x=cormlet weight. Cormlets developing on the corm bases sprouted earlier than did those which were attached higher on the corms, suggesting that cormlets which formed earlier on the corm bases became receptive to high temperature earlier than did those formed later at the upper nodes. Consequently, their time of sprouting of basal cormlets was advanced. After bud dormancy was broken, corms of 7.3-12.8g responded to chilling at 12 degrees C immediately after planting, and their apical meristem initiated flower buds. The interval between planting and when the apical meristem enlarges was shortened to three weeks when the growing period at 25 degrees C was lengthened. When cormlets weighing 0.8-1.8g were kept at 12 degrees C after planting, their apical meristem continued to form leaf primordia during the initial few weeks of shoot growth. To initiate flower buds within three weeks at 12 degrees C, plants needed to grow for six weeks at 25 degrees C prior to chilling. Our data indicate that sprouting of cormlets is retarded compared to the corms, furthermore, plants raised from cormlets are not induced to flower by chilling at their early stage of shoot development

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