Growth Regulator Effects in Seed Propagated Begonia X Tuberhybrida Progress Report — September 1991
Date August 22, 1991
Title of Project Growth Regulator Effects in Seed Propagated Begonia x Tuberhybrida
Institution where work is being conducted University of Alaska-Fairbanks
Amount of Endowment Grant $ 4, 100
Covering Period 01/91 to 12/91
Anticipated Date of Project Completion/Final Report Early 1992
Individual(s) Conducting Project:
(List Project Leader First)
Meriam G. Karlsson - Title Assistant Professor
Telephone Number (907) 474-7005
Growth Regulator Effects in Seed Propagated Begonia x Tuberhybrida
Meriam G. Karlsson
University of Alaska-Fairbanks
- A. Project Objectives:
- To determine the effects of treatments with Cycocel (chlormequat), B-Nine(daminozide), Bonzi (paclobutrazol) and Bayleton (triadimefon) on morphology and
developmental rate of seed propagated Begonia x tuberhybrida.
- To study the post-production performance of growth regulator treated B. xtuberhybrida plants.
- B. Summary of Work Conducted:
- Seedlings of B. x tuberhybrida ‘Musical Orange’ and ‘Clips Orange’ weretransplanted into 10 cm pots filled with a peat-lite medium, six weeks after seeding. The
plants were grown at 20′C (68′F) day and 181′C (64′F) night temperatures, and a day length
of 16 hours at 100 umol*m-2*s-1 (500 foot-candles). Plants were treated two weeks after
transplanting at application rates of 500 or 1,000 ppm. Cycocel, 2,000 or 3,000 ppm. B-Nine,
5 or 10 ppm. Bonzi, and 375 or 750 mg/liter Bayleton. Plants receiving two applications
were treated the second time one week after the first application. Plant height and leaf
number were recorded at weekly intervals.
- C. Results to Date:
- The results of this study indicated Cycocel to be the most desirable of the testedchemicals for height control in seed propagated tuberous begonia. Plant height was
reduced 20% for plants treated with 500 mg/liter and 25% for plants treated with 1000
mg/liter Cycocel, 15 weeks after transplanting. Discoloration of the foliage was limited
after chlormequat application at the studied rates.
- Although Bonzi and Bayleton applications resulted in shorter plants than Cycoceltreatment, the number of shoots and flowers also decreased for Bonzi and Bayleton treated
begonias. A lower rate than 5 mg/liter Bonzi may give a more preferable overall growth
and development of begonia. Application of Bayleton for powdery mildew control during
early begonia development can possibly result in stunted and slow growth.
- B-Nine application was not effective in controlling plant height at the studiedapplication rates. Despite a larger flower dry weight, the number of flowers was similar to
the number of the control plants.
- D. Future Plans Covered by the Endowment Grant:
- Data on morphology and dry weight were recorded 15 weeks after transplant on halfof the plants in each treatment. The effects of growth regulator applications on continued
development were followed in the remaining plants.
- E. Anticipated Benefits for Floral Industry:
- The seed propagated cultivars of B. x tuberhybrida have become popular during the1980s as potted plants, bedding plants and hanging baskets. Although temperature
manipulations can and are being used to control height in many plants, there is still a need
for growth regulators. Many of the growth regulator recommendations for seed propagated
tuberous begonia have been based on results with Begonia x hiemalis (hiemalis begonia
Rieger begonia or elatior begonia) despite the large production of B. x tuberhybrida. The
effects of growth regulators on rate of development morphology and post-production
performance for seed propagated cultivars of B. x tuberhybrida need to be determined to
establish reliable recommendations for commercial production.
