Seed to Food Update: Tomato trials and off-types

Posted on Thursday, 7 October 2021 under Stories Featured

Tomatoes have been the star of the show at our Research and Education Seed Farm. This season we are growing seven varieties. Hues of greens, yellows, oranges, and red fill our fields. We are growing four tomato varieties for seed including cherry green stripe, soleil, alpha, and Michael Pollan. We are growing the rest for trials, including the Stupice and Alpharora tomatoes from our Citizen Seed Trial. Crops from trials are perfect to donate to our partners at the Food Stash Foundation. This year we have donated around 25 kilograms of tomatoes from our trials as well as the early alpha tomatoes as they tend to produce fewer seeds.

produce donation to local charity

A portion of donations to the Food Stash Foundation from our Research and Education Seed Farm crops trials.

Another source of our tomato donations has been off-types found in our fields. The photo below shows a row that was supposed to be filled with cherry green stripe tomatoes, but we had one plant that bore red fruits. Similarly, in our soleil tomato population, there were two off-type plants. Soleil fruits are supposed to be orange in colour but one of the plants was slightly too red and the other slightly too yellow. While perhaps a bit picky, roguing the off-types is an important job to ensure plant lines stay stable and to produce seeds with predictable outcomes. Therefore we removed and donated all the tomatoes from any off-type plant as well as the tomatoes on surrounding plants to remove the potential for cross-pollination. This helps to ensure higher quality seeds and has the dual benefit of providing extra food for us to deliver to Food Stash.

tomatoes on a vine

Comparison of cherry green stripe tomatoes (left) with one plant that bore red fruit (right).

It is easier to grow multiple varieties of tomatoes to seed on one farm compared to some other crops because tomatoes are a largely self-pollinating crop. In self-pollinating crops, the transfer of pollen from the male anther to the female sigma occurs within the same flower and often before the flower fully opens. Modern tomato varieties can be grown within 10 feet of each other whereas older varieties require up to 25 feet of isolation distance due to their longer styles. A longer style will increase the chances of cross-pollination as it is less contained within the flower and oftentimes farther away from the male anthers. Therefore, passing pollinators and strong winds carrying pollen are more likely to intercept with a longer style. Keep this in mind when you are saving seeds from older heirloom varieties.

Looking for more information? Read about tomato isolation distances and watch our information video about flower morphology.