Module 1   The plant-soil-water system
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Lesson 1  

Water movement in soil plant atmosphere continuum


bulletTrace movement of water from soil to plant and to the atmosphere.


Rice plants take up water from the soil and transport it upward through the roots and stems and release it through the leaves and stems as vapor in the atmosphere (called transpiration). The movement of water through the plant is driven by differences in water potential: water flows from a high potential to a low potential (imagine free water flow over a sloping surface: water flows from the top, with a high potential, to the bottom, with a low potential). In the soil-plant-atmosphere system, the potential is high in the soil and low in the atmosphere. Therefore water moves from soil to plant and to the atmosphere.

The movement of water in the plants are affected by humidity, wind speed, temperature and solar radiation.This movement however, is not only determined by the factors above. It also affected by the soil water tension which are determined by soil physical properties such as texture and bulk density.

To compare effects of the different factors, click each of the conditions below.


high humidity high wind speed high temperature high solar radiation high water tension
low humidity low wind speed low temperature low solar radiation low water tension





Functions of water in the plant

To understand the importance of water to the plant, click on each of the images below.


water purpose


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Now that you can describe plant soil water continuum, we can proceed in discovering the effects of drought on rice.

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