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In ecology, pressure-volume curves describe the relationship between total water potential (Ψt) and relative water content (R) of living organisms. These values are widely used in research on plant-water relations and provide valuable information on the turgor , osmotic and elastic properties of plant tissues .
Directly - by measuring the reduction in mass of the potometer over a period of time. Here it is assumed that any loss in mass is due to transpiration. There are two main types of potometers: the bubble potometer (as detailed below), and the mass potometer. The mass potometer consists of a plant with its root submerged in a beaker.
A diagram showing the setup of a Pressure bomb. A pressure bomb, pressure chamber, or Scholander bomb is an instrument that can measure the approximate water potential of plant tissues. A leaf and petiole or stem segment is placed inside a sealed chamber. Pressurized gas (normally compressed nitrogen) is slowly added to the chamber.
Growing degree days (GDD), also called growing degree units (GDUs), are a heuristic tool in phenology.GDD are a measure of heat accumulation used by horticulturists, gardeners, and farmers to predict plant and animal development rates such as the date that a flower will bloom, an insect will emerge from dormancy, or a crop will reach maturity.
The pressure bomb technique was developed by Scholander et al., reviewed by Tyree and Hammel in their 1972 publication, in order to test water movement through plants. The instrument is used to measure turgor pressure by placing a leaf (with stem attached) into a closed chamber where pressurized gas is added in increments.
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The top of the tube has either a built-in vacuum gauge or a rubber cap used with a portable puncture tensiometer instrument, which uses a hypodermic needle to measure the pressure inside the tensiometer. The tensiometer is buried in the soil, and a hand pump is used to pull a partial vacuum.
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