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Wed, 31 May 2000 10:13:21 -0700 |
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Hayden Bee Lab, USDA-ARS,Tucson, Arizona |
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"J.F. Hensler" wrote:
> Robert Brenchley wrote:
> <Last year one of the few crops I actually got on my allotment (despite
> successive floods) was broad beans. The crop was appalling;
> We have raised both bees and broad beans here for years and I don't
> believe I have ever seen a honey bee on the beans. In our experience broad
> beans are wind pollinated
This seems to be a fairly complicated situation - here is what I found by
dipping into S.E. McGregor's "Insect Pollination of Cultivated Crop Plants",
which we maintain and update on our website. You may access it directly at
http://198.22.133.109/book/index.html
-This excerpt is from Chapter 5, Legumes and Relatives.
Pollination Requirements:
The pollination of broad bean and field bean was studied by Free (1966)
who
concluded that insect pollination greatly increased production of broad
beans but had
little effect on production of field beans. Later, Free (1970*) concluded
that the
pollination requirements of broad bean and field bean were similar
although
inadequate pollination limited seed production in broad beans more so than
in field
beans. Darwin (1889*) showed that 17 broad bean plants covered with a net
to
exclude pollinators produced only 40 seeds, whereas 17 exposed plants
produced 135
seeds.
Probably the most important observation concerning the pollination of
field bean was
that by Drayner (1956,1959) and confirmed in more elaborate detail by Bond
and
Fyfe (1962) who showed that continued inbreeding causes a progressive loss
in the
ability of the plant to set selfed seed, but upon hybridization
(cross-pollination) this
ability is restored. This means that the plant can survive several
generations (not
indefinitely) without cross-pollination although production continually
decreases. A
similar situation apparently exists in many other so-called
self-pollinated crops;
continued inbreeding leads inevitably to elimination of the strain.
- Hope this helps.
-----------------------------------------------------------
John F. Edwards
Carl Hayden Bee Research Center
Tucson, Arizona 85719
http://198.22.133.109/
http://gears.tucson.ars.ag.gov/home/edwards/edwards.html
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