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Department of Plant Agriculture

CHANGING LIVES, IMPROVING LIFE

Plant Agriculture
 

Research

Theo Blom

Dr. Theo J. Blom

Associate Professor

E.C. Bovey Building
Department of Plant Agriculture
University of Guelph
Guelph Campus
50 Stone Rd. E.,
Guelph, Ontario, Canada
N1G 2W1

Email: tblom@uoguelph.ca 
Phone: 519-824-4120 x. 53847
Fax: 519-767-0755

Greenhouse Floriculture Program Description

The greenhouse floriculture program concentrates primarily on problems / challenges in production management of floricultural greenhouse crops. The studies generally are applied in nature (production oriented). The team consists of David Kerec, research technician, and myself as the two permanent staff members. My appointment is split 0.75 research / 0.25 extension and other activities as assigned. Additional students are often hired to help with the program. I am co-advisor of Eric Wierenga and Hussain Ahmad and serve on the advisory committee of Lorraine d'Silva. Two Student co-supervised graduated: Karrie Thomas-Granger (2003) and Michael Ravensdale (2004).

The studies involve a comprehensive research program to improve various production management techniques for both cut flowers and potted plants through 5 objectives:

  • plant modifications through light quality, temperature manipulation, water temperature, change in biorhythm, or other non-chemical means.
  • more efficient use of production inputs such as energy, light, carbon dioxide and temperature control.
  • more sustainable production through optimizing nutrients and water through recirculation and disease management.
  • improvement of increased acceptability through species/cultivar selection or improved postharvest quality of potted plants or cut flowers.

Significance of greenhouse floriculture to the Agri-food industry and research.

  • Non-chemical height control. The use of cold water has shown to be very effective in controlling plant height when applied to the apical meristem of Easter lilies. The response has been linear, e.g. plant height increases linearly with water temperature. The response curve is very similar (same slope!) when plants are grown at different air temperatures (14, 18, or 22C). Height reduction of 50-60% has been achieved with Easter lilies, but is lower for hybrid lilies (7-15%). Early applications are more effective than late applications, and a slight delay in forcing time (4-5 days) has been noted when using very low temperatures (2d).
  • Comparison of PGR's on chrysanthemums. Daminozide (B-9) at 2500 ppm was about twice as effective as uniconazole (Sumagic) at 2.5 ppm on height control of pot mums. However B-9 caused a delay in flowering, especially early and more frequent applications. Also B-9 has shown to affect the colour of the popular bronze cultivar 'Pelee', especially when applied late. Sumagic did not show any delay in flowering date.
  • Photoperiod and supplemental lighting on cut gerberas. Gerbera cut flower production responded favorably to short photoperiod (8-h PP) in terms of number of stems produced to either 13-h or 18-h PP. However short photoperiod produced shorter stems with the cut gerberas. Supplemental lighting with high pressure sodium lamps at high light intensity (70 µmol/m²/sec) showed only marginal effect.
  • The effect of twilight (sunrise or sunset) on plant height. The elimination of twilight at the end of day (using black-out) is a very simple and effective technique to control plant height for many crops.
  • Alternative to case cooling of Easter lilies. The use of interrupted cooling for Easter lilies is a viable alternative for forcing Easter lilies compared to the previous standard cooling techniques used in the industry, such as case-cooling and controlled temperature forcing.
  • Post harvest studies on Easter lilies. The use of gibberellic acid (GA4+7) has been a very effective technique in preventing yellowing of the lower leaves of Easter lilies. Also, methylcyclopropene (1-MCP) has shown to be a very effective protectant against ethylene damage in both cut flowers and potted plants during shipping and initial shelf life.

Technology transfer. A proportion of my time is spent on transferring research information to commercial greenhouse growers through meetings, workshops, and responding to growers' inquiries. Also articles are written for the Industry trade to convey research results to greenhouse growers as well as for the scientific community. I coordinate and help teaching growers night schools (10 evenings/ semester) relating to topics relevant to greenhouse production.


Selected Publications

Books:

  1. Blom, T.J. and R. Criley (ed's). 2003. Proceedings of Symposium 'Elegant Science in Floriculture' of the International Horticultural Congress. Toronto. Aug, 2002. Acta Hort. 624. Volume 1+2.

Chapters in books:

  1. Verberkt, H., R. Heins, and T. Blom. 2004. Supplemental lighting of potted plants. Chapter in "Lighting Up Profits". P Fischer and E. Runkle(eds.). Publisher: Meister Media Worldwide, Willoughby, Ohio. ISBN 1-892829-10-X. First Edition. p72-78.
  2. Blom, T.J. 2004. End-of-day light response in lilies. Research Highlight in "Lighting Up Profits". P Fischer and E. Runkle(eds.). Publisher: Meister Media Worldwide, Willoughby, Ohio. ISBN 1-892829-10-X. First Edition. p74-75
  3. Blom, T.J. 2004. Using plant growth regulators for flower crops. In: Production Recommendations for greenhouse floriculture. OMAFRA Pub. 370:p79-84.
  4. Blom, T.J. and M. J. Tsujita. 2003. Cut Rose Production. In: Encyclopedia of Rose Science by A.Roberts, T. Debener, and S. Gudin (eds.) Elsevier Academic press. Volume 2: 594-600.
  5. Blom, T.J., A.J. Both and W. VanWinden. 2001. (Editors and translators for book). Supplemental lighting for greenhouse crops (J.J. Spaargaren, original Dutch author). Publisher: Hortilux, Beamsville, ON, 178 pp.

Papers (refereed):

  1. Blom, T.J., D. Kerec, W. Brown and D. Kristie. 2004. Irrigation method and temperature of water affect height of potted Easter lilies. HortScience 39(1):71-74.
  2. Dale, A. and T. J. Blom. 2004. Far-red Light alters primocane morphology of red raspberry. HortScience 39(5):973-974.
  3. Gracia-Garza, J.A., T.J. Blom, W. Brown, D.P. Roberts, K. Schneider, M. Friesen and D. Gombert. 2004. Increased incidence of Erwinia soft-rot on calla lilies in the presence of phosphorous. European J. of Plant Pathology. 110:293-298.
  4. Blom, T.J. and D. Kerec. 2003. Effects of far-red light/temperature DIF and far-red light/temperature pulse combinations on height of lily hybrids. J. of HortScience and Biotechnology 78(2):278-282.
  5. Gracia-Garza, J.A., M. Little, W. Brown, T.J. Blom, K. Schneider, W. Allen, and J. Potter. 2003. Efficacy of various biological control agents and biorationals against Pythium root rot in poinsettia. HortTechnology. 13(1):149-153.
  6. Blom, T.J., W. Brown, G.C.L. Chu, W.T. Liu, and L. Skog. 2002. Easter lilies react differently to short- or long- term exposure of ethylene or methane at different stages of forcing. 2002. HortTechnology 12(1):91-94.
  7. Gracia-Garza, J.A., T.J. Blom, W. Brown and W. Allen. 2002. Pre- and post-plant applications of copper-based compounds to control Erwinia soft-rot of calla lilies. Can. J. Plant Pathol. 24:274-280.
  8. Raviv, M and T.J. Blom. 2001. The effect of water availability and quality on photosynthesis and productivity of soilless-grown cut roses. Scientia Hort. 88:257-276.

Technical reports:

  1. Blom, T.J. and J. Gracia-Garza. 2004. Studies on the epidemiology of Erwinia soft-rot and their control in ornamental crops. Final report for OMAF Research project 44678. 12pp.
  2. Blom, T. J., D. Kerec, and R. Kamenetsky. 2004. Interrupted cooling as an alternative to case-cooled or controlled temperature forcing of Easter lilies. Proceedings of ISHS. Japan. Acta Horticulturae. (in press).
  3. Blom, T.J. and D. Kerec. 2004. The effectiveness of daminozide (B-9) and uniconazole (Sumagic) on height control and delay in flowering of pot chrysanthemums. Greenhouse Canada 24(3):29-31.
  4. Skog, L., T. Blom and W. Brown. 2004. The assessment of optimization of ozone treatment for control of fungal diseases and ethylene in greenhouse floriculture crops. Prepared for CGC. 24pp.
  5. Verberkt, H., R. Heins and T. Blom. 2004. Lighting up profits. Greenhouse Grower. 22(5):96-98, 100, 102.
  6. Blom, T.J. 2003. Controlling Easter lily height. GMPro 23(12):44-49.
  7. Blom, T.J. 2003. The effect of water temperature on height and flowering of bedding plants. Presented at the Canadian Greenhouse Conference, Toronto, October, 5pp.
  8. Blom, T.J. 2003. Nutrient Monitoring Workshop. Presented at the Canadian Greenhouse Conference, Toronto, October, 8pp.
  9. Blom, T.J., J. Gracia-Garza and W. Brown. 2003. The effects and control of Phytophthora root rot in a recirculating system for Gerbera production. ICFG Bulletin. Sept. p.28-30.
  10. Blom, T.J., D. Kerec and L. Skog. 2003. Evaluation of hydrating solutions fro Ontario grown cut flowers. Greenhouse Canada. p12-14, 16-18.
  11. Blom, T.J. and D. Kerec. 2003. The effect of high pressure sodium lighting and photoperiod on the flower production of cut gerberas. Tech report for ICFG. 3pp.
  12. Blom, T. 2003. "Hands-on" growing experience part of U of G course projects Greenhouse Canada. July. p28, 29, 31, 39.
  13. Blom, T. 2003. Awaken. A research report on the effect of Awaken on rooting of chrysanthemums and geraniums for UAP Canada. 3pp.
  14. Gracia-Garza, J.A., K. Schneider, W. Brown, and T. Blom. 2003. Do soilborne pathogens move from infected pots into the irrigation water in closed irrigation systems? Greenhouse Canada. Jan. p. 22-25.
  15. Blom, T.J. 2002. Coco coir extract for cucumbers, tomatoes and mini-roses. Greenhouse Canada. Nov. p. 25-28.
  16. Blom, T.J., D. Kerec and L. Skog. 2002. Evaluation of 'Florever' as a hydrating solution for Ontario grown cut flowers. Report for Plant Products. 6 pp.
  17. Blom, T.J. and D. Kerec. 2002. Light transmission of films. Report for Klerk's Plastics. 2 pp.
  18. Blom, T.J., J.A. Gracia-Garza and W. Brown. 2002. Effects and control of Phytophthora root rot in a recirculating system for gerbera production. ICFG Bulletin. p. 31-35.
  19. Blom, T.J. 2002. Radiation, light, greenhouses and plant growth. 6 pp. Handout for greenhouse growers, Leamington.
  20. Blom, T.J. 2002. New Approaches to Forcing Easter Lilies. Greenhouse Canada. March. p. 8-11.
  21. Blom, T.J. and P. Fisher. 2002. Easter Lilies: A challenge you can master. GPN. March. p. 10-17.
  22. Gracia-Garza, J.A., K. Schneider, W. Brown, and T. Blom. 2002. Spreading of soilborne pathogens in closed subirrigation systems. Greenhouse Canada. Dec. p. 6-7.

Greenhouse Floriculture Links

Grower Notes : the Ontario Floriculture Update
Canadian Floriculture, Nursery and Christmas Tree Situation and Trends
Greenhouse Floriculture : State of the Industry
Commercial Floriculture Production Information - B.C. Ministry of Agriculture and Food
Ontario Flower Growers Home Page
Flowers Canada (Ontario) Inc.
Greenhouse Flower and Plant Production, Ontario and Canada
Greenhouse Industry Statistics, Ontario and Canada


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