"Self Pollinating" and Tomato Growing Mythology
Long ago, a group of monks got into a discussion of horses teeth. How many
did a horse have? All the ancient writings were consulted, and the discussion became more
and more heated. Finally a young monk suggested they look in the horse's mouth. One and
all turned on this impertinent, irreverent monk and they literally threw him out of the
monastery.
At risk of being thrown out of tomato groups, I will try to inject some
common sense into the tomato pollination discussion. It's funny how often it's said that
tomatoes self pollinate, but always in the context of ways to help them self pollinate, or
reasons why they didn't self pollinate. Oxymoronish isn't it?
The best pollinator for tomatoes is the original, a bee which
"sonicated" at the resonant frequency of the flower. Sonication, also called
buzz pollination is when the bee vibrates its wing muscles but doesn't fly; it just hangs
on.
The reason is that tomato pollen is not in the exterior of the anthers like
most flowers, rather it is produced internally and then released thru pores in the anther.
Motion is required to release the pollen, and the greatest quantity is released by
sonication of the correct frequency. However other bees with different frequency, or even
shaking by wind will release some pollen.
There are a couple problems: one is that the natural pollinator (a wild bee)
didn't travel with the tomato as it was spread throughout the world. The other is that the
flower is not very attractive to other bees, and when bee populations are low the tomato
generally gets ignored. Bumblebees are the most often seen on tomatoes, though honeybees,
when hungry enough will also work them, as will some solitary bees.
Did you ever watch a bumblebee work a tomato blossom? When it does, it pulls
the flower down into a vertical position, puts its fat belly against the stigma, and
buzzes. The pollen that is released, now will fall by gravity (since the flower is now
tilting down) directly to the bee's fuzzy (and statically charged) belly, which is rubbing
against the sticky stigma as it vibrates. Tomatoes are self fertile, but the pollen can
come from any other tomato that the bee has visited, a bane for seed growers who want to
keep varieties pure, but lovely for the gardener who wants fruit.
The size of the fruit is dependent on the number of ovules fertilized, up to
the 100% mark. In other words, the more seeds, the meatier the 'mater. So we want to get
pollination as full as possible. This is the reason the bee is best, it delivers the most
grains of pollen, exactly where it is needed, on the sticky surface of the stigma.
When shaking is done by hand, think about mimicking the natural resonances of
sonicating bees. Shaking should not be violent, just as close to the right frequency as
possible. Electric vibrators were long used in greenhouses for tomatoes, but have been
replaced, as bumblebees are found to be far more efficient. Using an artist brush with
tomatoes is very inefficient because the pollen is not on the surface.
Yup, tomatoes are self fertile, but self pollinating?...only when conditions
are ideal...they often need help. "Self pollinating" is one of the myths of
tomato growers.