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University of Florida/IFAS
Institute of Food and Agricultural Sciences
Central Florida Research and Education Center
CFREC-Apopka Research Report RH-96-11
R. J. Henny and T.A. Mellic*
Attractive foliage makes aroid genera such as Aglaonema, Dieffenbachia, Homalomener and Syngonium popular, while genera such as Anthurium, Spathiphyllum and Zantedeschia are valued for their beautiful flowers. Whether flowers are used as a sales tool or in breeding, the ability to stimulate aroids to bloom is an important technique. Fortunately, research has shown that application of the plant growth regulator, gibberellic acid (GA3), to aroids will induce flower production. This paper summarizes the most current information relating to use of GA3 for stimulating flowering of nine genera of ornamental aroids.
Aroids can be induced to flower by treatment with GA3, which can be purchased in a liquid formulation (Gib-Gro, 4% GA3, Agtrol Chemical Products, Houston, Texas). A single foliar spray is the easiest method of applying GA3 and works well. A wetting agent should be added to the treatment solution to aid in coverage and the foliage should be thoroughly covered until runoff. A tuber soak for Caladium and a rhizome soak for Zantedeschia were also effective treatment methods. A general treatment concentration range is between 250-500 ppm (1 ounce of Gib-Gro per gallon of water = 250 ppm GA3). The response to GA3-treatment of these and other aroid genera are summarized in Table 1.
Under Florida growing conditions, different aroid species within a genus may flower unpredictably. For example, most Aglaonema and Dieffenbachia species flower in late winter and early spring; however, some species consistently flower at other times of the year or not at all. Inability to flower species simultaneously is a major hurdle in breeding studies and can hinder sales of genera whose flowers are a sales asset. Flowering of Spathiphyllum with GA3 treatment originally was for breeding purposes, but this discovery soon led to development of a production system whereby growers could use GA3 to ensure a supply of flowering plants throughout the year. On the other hand, forced flowering of Aglaonema and Dieffenbachia is only for breeding since their flowers have no ornamental value.
Generally, GA3-treated plants produce more flowers compared to natural flowering. This effect is particularly evident in Aglaonema and Dieffenbachia where flower counts on treated plants may double those obtained from natural flowering. In addition, higher GA3 rates generally yield more flowers than lower rates.
Time from treatment to the presence of open flowers may range from 7 weeks for Caladium to 20 weeks for Aglaonema and Homalomena. However, most genera flower within 12-15 weeks of treatment (Table 1). These intervals are only approximate and will vary significantly depending on the season. Plants treated during the summer flower faster in response to GA3 than those treated in winter. For example, GA3-treated Spathiphyllum 'Petite' may flower in 8-10 weeks in the summer but the same cultivar may require 16-20 weeks to flower in the winter depending on the minimum temperature range. In general, the faster a plant's growth rate the faster its response to GA3 treatment. Different species and cultivars within a genus generally flower together if treated simultaneously with GA3. No detrimental effects to fertility have been observed due to GA3 treatment.
Plants treated with GA3 tend to produce narrower leaves for a period following treatment. In Spathiphyllum, some flower distortion may occur, the extent of which varies with cultivar. GA3 treatment has proven to be a reliable method to stimulate flowering of several ornamental aroid genera. It is currently used regularly to allow nurserymen to produce a continual supply of blooming Spathiphyllum. The other major role of GA3 will remain as an aid to plant breeding efforts in ornamental aroid genera.
*Professor of Environmental Horticulture and Biological Scientist, University of Florida, IFAS, Central Florida Research and Education Center, 2807 Binion Road, Apopka, FL 32703, respectively.
NOTE: Mention of a product does not constitute a recommendation or warranty of the product by the authors or the University of Florida, nor does it imply its approval to the exclusion of other products.
|Aglaonema||breeding||foliar spray||200-400||142-144||Henny, 1983|
|foliar spray||375-500||88-95||Henny &
& Wilfret, 1979
|Dieffenbachia||breeding||foliar spray||250-500||89-93||Henny, 1980|
|Homalomena||breeding||foliar spray||100-400||134-140||Henny, 1988|
|foliar spray||250-500||98-112||Henny, 1981;