Determining the Water Potential of Potato Tubers Using Gravimetric anc Chardakov Techniques

Determining the Water Potential of Potato Tubers using Gravimetric and Chardakov Techniques

1. INTRODUCTION:

Water potential (W) is the measure of free-energy status of water in plant cell, which is the driving force governing the movement of water into and out of the plat cell and affect various metabolic activities (O’Leary, 1970). Water potential is depends on different solute concentrations, pressure and matrix a particle; measured in Mega Pascal’s (MPa) and written as:

W = s + p + m

In plants dissolved solutes such as ions, sugars, proteins, amino acids and other substances decrease the availability of free energy and induce solute potential (S) , having a negative value. Another factor affecting W is the pressure potential (P) which could be either positive for turgor cells or zero for flaccid cells or negative for cells with active transpiration. Also the binding of water to colloids which decreases water potential is known as Matric Potential (m), it is often small and considered a component of solute potential (Saupe), so for convinces it is ignored and now the equation is:

W = s + p (1)

Water Potential can be determined by measuring the equilibrium vapor pressure, which can be measured by varied methods based on different parameters for this purpose utilizing gravimetric parameters (Length, volume and weight) or Chardakov methods of using specific gravity changes (O’Leary, 1970) or Chardakov pressure bomb chamber or Freezing Point Depression determination using hydrolytic pressure chambers or Cryoscopic or Oblioscopic methods amongst others ( Bland and Tanner, 1985). In this experiment The Gravimetric and Chardakov techniques are used for determining the W for potato tubers by incubation in inc...

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...of the water potential of stored potato-tubers. Plant Physiology 79 (3), p 891-895. Available From: http://www.plantphysiol.org/content/79/3/891

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Saupe S.G. Measuring the Water status of Potato tubers. St. John’s University, Minnesota. [Online] Available from: http://employees.csbsju.edu/ssaupe/biol327/Lab/water/water-lab-intro.htm [Access date: April 12, 2014]