Re: [beemonitoring] Re: Plant skipping in a cropping system
As Nancy says - change of flower color - I have seen cotton flowers changing in the same way, from white to pink when pollination occurs (this is Gossypium hirsutum in Colombia; I don't know if the same happens in other cotton species around the world).
For other side, differences in water balance between plants (which could varies from plant to plant, mostly if soil preparation for the crop was not homogeneously done) could cause different nectar offer and density (sugar concentration). Parallel to this, the behavior of these 2 variables across the day (sun) will be different according the water availability for each specific plant/site. Certain bees have preferences related with these variables. They could detect this variations and choose plants according to their preferences. This is the first idea that came to my mind; I hope it helps.
Jaime A. Florez
ARS - USDA Bee Lab
Dept. Biology & Ecology Center
Utah State Univesity
--- El mar, 3/15/11, Cowden, Nancy <Cowden@...> escribió:
De: Cowden, Nancy <Cowden@...>
Asunto: [beemonitoring] Re: Plant skipping in a cropping system
A: "'firstname.lastname@example.org'" <email@example.com>
Fecha: martes, 15 de marzo de 2011, 02:47 pm
I’m not absolutely sure with watermelons, but many plants will alter the uv patterns flowers produce depending on the reproductive status of the individual flower. This could certainly be the case for watermelon. Also, recognize that individual watermelon flowers are either male or female – producing pollen or not. If a bee is specifically foraging for pollen but not nectar, it would visit male flowers but not females.
An example of a flower that sends a signal clear enough even for humans to detect is the change in the spot color on the banner petals of bluebonnets (some Lupinus sps.) – white prior to pollination, pink to purplish after pollination. The bees visiting bluebonnets will almost always skip over flowers with pink to purple spots.
Nancy E. Cowden, Ph.D.
Associate Professor of Biology
Curator of the Ramsey-Freer Herbarium
Assistant Director, Westover Honors Program
1501 Lakeside Drive
Lynchburg, Va. 24501
- --- In firstname.lastname@example.org, "Jaime A. Florez" <jaimef69@...> wrote:
> As Nancy says - change of flower color - I have seen cotton flowers changing in the same way, from white to pink when pollination occurs (this is Gossypium hirsutum in Colombia; I don't know if the same happens in other cotton species around the world).I would think this a fantastic opportunity for a research project. Does the color change at deposition of pollen, at initiation of pollen tube growth, at fertilization? How many grains of pollen/pollen tubes/fertiizations would be needed to trigger it?
(Pollination is not a binary event with a multiseeded fruit. It is progressive, depending on the number of incipient seeds fertilized.)
A whole lot of questions come racing into my mind.
Alfalfa flowers change from purplish to grayish after tripping (generally equivalent to pollination). An interesting story on the lack of understanding of pollination needs comes to mind:
In the 1920s and 30s in the US state of Utah, farmers observing alfalfa color change, thought this represented damage to the plants, when it really represented pollination. Migratory beekeepers coming from California had begun using Utah alfalfa fields as a honey crop. But the farmers were able to convince the state legislature to pass a ban on migratory beekeepers coming into the state.
California beekeeper, Harry Whitcombe, became convinced that alfalfa needed more bees for pollination than would ever be placed by beekeepers for honey production. Together with a scientist, George H. Vansell, at the University of California, Davis, they tried to find farmers who were willing to pay a small fee to beekeepers to stock extra bees on alfalfa seed fields.
No one was willing to do this, however one farmer, Stan Good of Woodland, agreed to pay the beekeeper a percentage of any production above a figure that represented an extraordinary crop - and the beekeeper decided to take the risk. He stocked the bees as proposed - five hives per acre.
The seed yield was so heavy that the harvest machinery broke down and almost caused a failure of the test. But the ag mechanics at Davis redesigned the harvest machinery with heavier bearings, etc, and the harvest was gotten.
The average yield at that time was about 220 pounds per acre, and the test produced alfalfa seed at very close to 1000 pounds per acre.
The yield was so phenominal that the beekeeper made a small fortune, the seed grower was rueful that he could have had the services of the bees for a much smaller fee, and the concept of "Saturation Pollination" was born.
Saturation Pollination is the practice of maintaining higher bee populations than would be normally present for honey production, in order to make sure that every blossom gets the optimal number of bee visits for complete fertilization of all possible seeds.
Utah, by the way, lost its leading position as an alfalfa seed producer, never to gain it back (though they rescinded the ban on beekeepers), and California took over that lead.
Since then, it has been shown that honeybees are not the most efficient alfalfa pollinators. But it is a clear example how the lack of understanding of pollination has cost agriculture dearly.
Retired pollination contractor
- The color change in Lupinus (at least texensis) is age related and occurs with or without pollination (Schaall and Leverich, 1980 Southwestern Naturalist 25:280-282). Similar age related color changes occurs in many other plants so one needs to be careful about using color changes as an indication of pollination. The presumed "point" of the color change is topotential pollinators about unrewarding flowers, not necessarily previously pollinated ones.bestJackJohn L. Neff
Central Texas Melittological Institute
7307 Running Rope
Austin,TX 78731 USA
- Thank you everyone for your responses. I've never worked with crop pollination before, and really don't know much about watermelon other than it tastes good. I'll bring this information back to the grower, and we'll see what we can figure out.