Effects of ancymidol and gibberellins A3 and A4+7 on Tulipa gesneriana L. cv. Paul Richter during development in the greenhouse

The influence of soil drench applications of ancymidol (0.5 mg), GA₃ (25 mg), and Ga₄₊₇ (25 mg) was determined on the growth and development of the tulip under greenhouse conditions. Ancymidol applied on greenhouse day 1 or 6 significantly reduced the total length of the scape. Maximum reduction in growth occurred in the first internode, with a declining effect on internodes 2, 3 and 4. GA₄₊₇ applied simultaneously with ancymidol completely reversed the ancymidol effects. GA₃ was relatively ineffective. Compared to control plants, ancymidol reduced the number of cell divisions in the first internode, but not in the fourth internode. Cells of ancymidol treated plants were reduced in length and exhibited greater radial expansion. Ancymidol reduced the fresh weight of the stem and tended to conserve the fresh weight of the mother scales. The effect on the leaves and roots was variable. Ancymidol tended to increase the fresh weight of the daughter bulblets. There was no significant effect of ancymidol or the GA's on floral morphology or the number of days to flower in the greenhouse.