The relationships between gibberellin and organ size in colored <i>Zantedeschia</i> cv. ‘Calla Gold’

Abstract

Involvement of gibberellin in the regulation of size and shape of different plant organs (leaf, floral stem, and tuber) were studied in colored Zantedeschia cv. ‘Calla Gold’ (CG). The effect of gibberellin on allometric relationships between these organs was also examined. Tubers were dipped in solutions of GA3 (0.6 mM) or of the gibberellin biosynthesis inhibitor Uniconazole (3.4 mM) prior to storage, prior to planting, or twice—before storage and before planting. The effects of the growth regulators were followed in plants grown in pots in a screen house under 50% shade. Tuber weight was reduced by both GA3 and Uniconazole, but by different processes. GA3 increased the number of the floral stems per plant, but did not affect floral stem length or blade and petiole length. Uniconazole reduced the proportion of flowering plants, and inhibited leaf and stem elongation. Co-application with GA3 canceled the inhibitory action of Uniconazole on leaf and peduncle elongation. This suggests that gibberellin is in...