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[Plant-biology] Re: question

dh321 At excite.com via plantbio%40net.bio.net (by dh321 At excite.com)
Wed Jan 17 19:51:51 EST 2007

The seediness of some cultivars (cultivated varieties) such as
mandarins, tangors and tangelos is increased due to cross-pollination.
Often, the undesirable cross-pollination is prevented by not growing
trees of other cultivars near enough for pollination to occur, rather
than trying to exclude the bees. Navel oranges are genetically seedless
and pollinators, such as bees, do not need to be excluded for them to
produce seedless fruit, even if other cultivars are nearby.

Citrus pollination

Sex, Seedlessness, and New Varieties

There are crops where pollinators, such as bees, have to be excluded to
prevent seed formation, as in seedless cucumbers grown in greenhouses.
Pineapples are naturally pollinated by hummingbirds, which are banned
from Hawaii to prevent cross-pollination and seed formation in
pineapple fruit.

Seedless watermelons must be cross pollinated in order to stimulate
development of seedless fruit.

Seedless grapes must be pollinated and fertilized. The tiny seed then
aborts early in development so the fruit is essentially seedless.

There are several mechanisms for seedless fruit development. Exclusion
of pollinators is just one. Seedlessness in fruit is usually due to
parthenocarpy. In most seedless grapes, it is due to stenospermocarpy.

David R. Hershey

Barbara Beatie wrote:
> Please help. I am a  law student researching a problem.
> (That means my grasp of science is limited!)
> Do situations exist  where a farmer who has a seedless
> orange crop ever has other bees fly in and pollinate his crops (and
> render them useless
> since they'll have seeds?) Is anything written about this?
> Thanks,
> Barbara

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