ARS | Publication request: GIBBERELLIC ACID AND BENZYLADENINE PROMOTE EARLY FLOWERING AND VEGETATIVE GROWTH OF MILTONIOPSIS ORCHID HYBRIDS.

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 2, 2005
Publication Date: January 20, 2006
Citation: Matsumoto Brower, T.K. 2006. Gibberellic acid and benzyladenine promote early flowering and vegetative growth of miltoniopsis orchid hybrids.. HortScience, 41:131-135.

Interpretive Summary: The flower is usually the most important feature in marketing orchids. Timing flowering for special occasions or times of the year is helpful for orchid producers to meet the consumer demands. Flowering of the pansy orchid or Miltoniopsis is dependent upon the variety of orchid, cool temperatures and long nights. Provision of these requirements are often cost prohibitive to the grower. Here we describe the use of two plant growth regulators, gibberellic acid (GA) or N-benzyladenine (BA) alone or in combination to determine the effect on flowering. BA treated plants produced more shoots and delayed flowering while GA treatments promoted early flowering relative to the untreated plants. Plants treated with GA also produced more flower spikes per plant and the flower deformities were not observed. This suggests that GA may be helpful to orchid producers to optimize Miltoniopsis flowering without expensive modifications to control temperature and day length.

Technical Abstract: Flowering of Miltoniopsis orchids is influenced by a combination of cool temperatures and short photoperiod. To determine if application of plant growth regulators could promote flowering without the need for costly structural modification to control photoperiod or temperature, we utilized drenches of gibberellic acid (GA3) (2.5 mM or 5 mM), N6-benzyladenine (BA) (25 mM or 50 mM) alone or in combination. BA (25 mM or 50 mM) treatments promoted new vegetative shoots and decreased the number of plants with inflorescences compared to the untreaded control plants. This reduction of flowering and increased vegetative shoot production was alleviated by the addition of GA3 in combination with BA. However, the number of plants with inflorescences remained lessr than the control. GA3 hastened Miltoniopsis inflorescence emergence during the first flowering season by 10.9 to 14.9 days for Bert Field 'Eileen' and by 48.7 days for Rouge 'Akatsuka'. The number of Bert Field 'Eileen' inflorescences produced per plant were increased from 2.2 to 3.0 with 2.5 mM GA3 treatment. Flower deformities were not observed in the GA3 treated plants, and flower size and inflorescence length were unaffected by the GA3 treatment.