Effect of daminozide and flurprimidol on growth, flowering and bulb yield of Eucomis autumnalis (Mill.) Chitt.

Eucomis autumnalis (Mill.) Chitt., commonly known as pineapple lily, is a new ornamental pot plant with great marketing potential. This work evaluated the effects of two gibberellin synthesis inhibitors (daminozide and flurprimidol) applied as commercial plant growth regulators (PGRs) B-Nine and Topflor on the growth, flowering, and bulb yield in E. autumnalis. The PGRs were applied three times as substrate drenches or foliar sprays at the concentration of 15 mg dm^-3 (flurprimidol) or 4250 mg dm^-3 (daminozide). Plant growth was restricted only by flurprimidol, particularly when it was applied as substrate drenches. Plant height was reduced by 48% at anthesis and by 38% at flower senescence, compared to the untreated control. Regardless of the application method, flurprimidol increased the leaf greenness index (SPAD) and bulb weight. Daminozide treatments were ineffective in controlling plant height and negatively influenced bulb weight. Foliar sprays of daminozide increased the length of inflorescences and the number of flowers per inflorescence.