Greenhouse Canada

Features Crop Culture Inputs

January 18, 2008  By Dave Harrison

Does plant stress affect bumble bee pollination of greenhouse tomatoes?

11That’s the focus of a study recently launched at the Centre. Involved in the project are Dr. Les Shipp of Agriculture and Agri-Food Canada, Dr. Peter Kevan from the University of Guelph, greenhouse vegetable specialist Shalin Khosla with the Ontario Ministry of Agriculture, Food and Rural Affairs, and University of Guelph student Andrew Morse.

The project was prompted by pollination problems experienced by some growers in double poly greenhouses. “It’s worse at certain times of the year than others,” noted Dr. Shipp.


The issue was addressed in the past by adjusting light quality transmission into the greenhouse, said Khosla. “We still need to find that one extra piece of the puzzle.”

Morse said that they have set up different growing conditions in their three greenhouses. The growing conditions in the first greenhouse encourage vegetative growth, the second greenhouse is traditional growth, and the plants in the third greenhouse are generative.

The researchers will compare pollen and floral scents that develop on the flowers in the respective greenhouses.  This will determine if floral scents are related to plant growth stage, and if the quality and amount of pollen is also affected.

Morse said they will be looking at how much pollen is made, how much can easily be removed from the flower, and how much of that pollen will successfully germinate from each of the respective growing treatments.

Floral scent will be evaluated by enclosing flowers in an airtight bag. Clean, filtered air will then be vacuumed over the flower to be collected by a scent trap over a set period of time.

AAFC chemist Dr. Brian McGarvey will use a gas chromagraph-mass spectrometer to analyze each sample. This will determine what chemical molecules the flower was releasing, and how much of these volatiles were released during the testing time frame.

“By doing this a few times a day,” Morse explained, “we can learn when the flower is releasing what molecules, and with the help of our bumble bees, it will tell us if the different growth regimes affect the attractiveness of the plant.”

Dr. Shipp said this may mean growing plants more generatively at certain times to get more flower sets and fruit.

Collaborators include the Ontario Greenhouse Vegetable Growers association, Agriculture and Agri-Food Canada, the Ontario Ministry of Agriculture and Rural Affairs, and the University of Guelph.

“This is truly a multi-disciplinary project,” said Dr. Shipp. “We need all the partners involved, because no one person can do this kind of project.”

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