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Thread: It keeps getting better and better

  1. #41
    srduggins's Avatar
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    If the plant's sex doesn't change, at what point during it's growth is the sex determined? In the seedling stage, or as it enters sexual maturity? In other words, when do I need to abuse my plants to get more females?
    A day without Nepenthes is like a day without sunshine

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    I wonder whether it's causative or correlative. For example, in many reptiles, gender is a direct result of temperature during incubation. So the environment causes gender selection. However in humans, for example, male and female sperm appear to be differently suited to various conditions, so workers at nuclear power plants have disproportionately high numbers of female? children.

    So with the example of rafflesiana, does the exposed position cause seedlings to become male, or is it that only male seedlings can survive those conditions...?
    Demystifying Nepenthes: http://www.nepenthesforeveryone.com

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    Hi all:

    Similar events have been shown with alligators in the Florida Swamps where the proportion of female alligators is greater than the male population and this was shown to be due to exposure of dioxines in the water. Somehow sewage water is mixing with swamp water and causing more female alligators to be around. Please note that in this case, i am almost certaint that the alligators do have sex determining chromosomes.
    I guess we are jumping too much amongst reptiles, humans, and plants



    Gus

  4. #44
    It's been one of dem days BigCarnivourKid's Avatar
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    Quote Originally Posted by [b
    Quote[/b] (agustinfranco @ Mar. 22 2006,3:21)]I guess we are jumping too much amongst reptiles, humans, and plants



    Gus
    Good! I'll toss in fish . There was a study on the fish in the river near Denver, Colo. not too long ago into why there were so many fish with both male and female reproductive organs. In some parts of the river, there were very few male fish at all. Seems that female hormones were passing through the wastewater treatment plants into the river. The high hormone levels are thought to be due to the increase in the use of estrogen for variouse treatments from infertility to low bone calcium in women.

    To get this back on topic, I suggest we use the water from tha river to water our Neps to see if that will increase the number of female plants being grown.

    Sometimes my genious scares me!
    ---Steve Allinger---

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    My Grow List

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    So with the example of rafflesiana, does the exposed position cause seedlings to become male, or is it that only male seedlings can survive those conditions...?
    Good question, Hamish, and I don't believe the book addressed that point. in fact, Clarke claims it was inconclusive and really required more investigation. I believe they found similar ratios in N. ampullaria. I will check when i get home.

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    Very interesting and educational, to me at least.


    N
    Quote Originally Posted by [b
    Quote[/b] ]So with the example of rafflesiana, does the exposed position cause seedlings to become male, or is it that only male seedlings can survive those conditions...?
    I know exactly the places Charles made those observations on N. rafflesiana, I was with him. Rarely a female to be seen. The pure white silica sand around reflects the heat and makes it almost unbearable for people. Light levels are incredible and it's so bright that on a sunny day sunglasses are a must, otherwise you can hardly open your eyes to squint. Conditions there have been constant for many years, so it's probable that the plants experienced that harshness from the seed.

    However... in areas where a sudden trauamatic event has taken place to turn otherwise pristine forest into a disaster zone, such as occurs when whenever man intervenes, large plants will immediately flower and I believe more females than males appear. This contradicts the theory that a stressed plant will produce a male flower since it takes less nutrients to prduce pollen than fruit.

    Here's another piece of anecdotal information: we have 71 large stock plants of different clones of N. ampullaria 'Brunei red' 'Harlequin' and 'Williams red' in cossetted conditions in the nursery which we've been trying to flower for years. Only one has flowered there so far and it happens to be a male. We took 6 plants out of the nursery into full sun and stressed them severely. 5 of the 6 have now flowered - all female. What are the chances of that sexual expression being random?
    Rob Cantley
    Nep Nut in Sri Lanka
    http://www.borneoexotics.com

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    Hi Rob:

    Nice example to make us think hard about the nature of these plants!. If I were you, i'd expose another 6 plants to the same conditions and if all 6 are still female, you have made a big discovery! If not, i guess you should have bought a lottery ticket!

    Gus

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    I did my homework.
    According to Clarke, Christopher Frazier actually did a study at two sites using N. rafflesiana, ampullaria and gracilis as the study plants. The two sites had both 'closed' and 'open' microenvironments. In the 'open' areas, 100% of rafflesiana was male, and 83% of gracilis was male. there were no ampullarias growing in the 'open' areas. In the closed areas, females accounted for more than 50 percent of the flowering plants, with the number hovering around 60 percent+. This fits in precisely with Rob's plants grown 'close' and then exposed to 'open', the larger population of females reveal themselves-when stressed. Frazier noted the need for females to expend more energy bearing fruit and seed and would thus require a more nurturing environment. The males could tough it out on the white sand. He also noted that the male flowers in the open were more accessible to potential pollinators-higher visibility, and produced less sugar than the females. He suggests its to get the pollinator to the male flower just long enough to pick up the pollen, and then find the larger quantities of sugar at the female flower, spend more time at the female, assuring pollination.

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