Water and Plants

  1. How much time does it take for a plant to start taking water up to it roots through the stem to its other braches once you have watered it?
  2. jcsd
  3. DaveC426913

    DaveC426913 16,534
    Gold Member

    Sounds like a good experiment! Get a plant and some food dye and knock yerself out! Don't forget to let us know your conclusions!
  4. jim mcnamara

    jim mcnamara 1,563
    Science Advisor
    Gold Member

    Dave's suggestion is how florists get carnations with interestingly striped petals, for example. It's fun, you should try it.

    Soil water uptake rates vary a lot from species to species, time of day, ambient temperature, soil microstructure, and relative humidity.... some plants even get all their water from condensation on leaf surfaces - like Welwitschia mirabilis. Epiphytic orchids and plants like Tillandsia (Spanish moss) absorb water from dew or rainfall directly onto specialized aerial root systems.

    If you take Plant Physiology - unless you are a Botanist I do not recommend it - you'll spend at least half a semester on plant/water relations. It ain't that simple.


    The basic model is easy to understand. For example, in order to actively move water, plants have to have open stomates or have spongiform tissue that is low on water. Most plants rate of water uptake at night is much slower because stomates are closed.
  5. Exactly how can I perform this experiment? What does food dye have to do with this? :confused:
  6. russ_watters

    Staff: Mentor

    I'm pretty sure I did that experiment in elementary school. If you feed it colored water, it'll turn that color as the water gets sucked-up the stem.
  7. Moonbear

    Moonbear 11,955
    Staff Emeritus
    Science Advisor
    Gold Member

    As Russ pointed out, you feed them colored water (the food dye is just a safe coloring to use). The food dye is taken up with the water. But, I'm not sure if that works through the roots. I've done this with cut stems immersed in dyed water. The roots might be better at filtering what they take up.
  8. So if you have a red colored water and you pour it into the plant, would the whole plant turn red or just the leaves?
  9. russ_watters

    Staff: Mentor

    Moonbear might be right about needing to cut the stem and put it in a bath of colored water (hey - it was 20 years ago!), but anyway....
    The stem will slowly turn red as the water rises up through it.

    Google finds many references to this: http://sps.k12.ar.us/massengale/water_movement_in_celery_stems.htm
    Last edited: Aug 22, 2007
  10. jim mcnamara

    jim mcnamara 1,563
    Science Advisor
    Gold Member

    Dark blue works better. It's easier to see. Red makes the petals a more interesting color, if petals are a light color to start with. Use food coloring - the liquid dye that comes in little bottles. Some commercial dyes are not friendly to plant tissues.

    The dye can work up through the stem and into the petals of a flower in a few hours if you use a cut flower. Moonbear is right - the cell membranes in root hairs may filter out foreign molecules, like dye.

    More importantly, dyes bind to organic matter in the soil long before they get to the root hairs. If you grow plants hydroponically, you can add dye to the growth medium and the plant will suck up some of it, depending on the dye molecule.
  11. Evo

    Staff: Mentor

    If the roots aren't damaged it's immediate. I used to do a lot of work with roses which would come bare rooted. You put the bare roots into a bucket of water, they will start taking in water immediately.

    As for other plants. Take a plant with roots and knock or wash off the dirt. Let it start to wilt, then place into tepid water, Usually within an hour the plant will look the same as before it started to wilt. Just be careful not to let it wilt too much, you'll just end up killing it.
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