Changes in flower bud development ofZinnia elegansJacq. as influenced by the growth retardant S-07

Abstract

SummaryZinnia elegans treated with S-07((E)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol) produced single or half-double flowers, a result of fewer ray florets; this phenomenon was counteracted by GA3 treatment. The developmental changes in flowering induced by S-07 were further observed by scanning electron microscopy (SEM). Treatment of plants with S-07 delayed both the transition from the vegetative to the reproductive stage as well as the reproductive development of the shoot apex by about four days. In the floret formation stage, the petals of the control flowers elongated continuously and remained rounded whereas those of S-07 treated plants became flattened, split into five or six lobes and gradually covered the stamen primordia. The stamen primordia within the base of petals were larger and more well developed following S-07 treatment, compared with the control ones. Further, tubular florets were not formed after S-07 treatment at a late reproductive stage. It is therefore ...