© 2011, 2007, 2002, 1988 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ Practical Horticulture 5 th edition By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky tab Chapter 12 - Water Relations Water - Uses in Plants Water makes up approximately 90% a plant’s mass. –It is required for seed germination, serves as part of the plant’s structure, carries minerals into/through the plant. –It transports photosynthates & biochemicals and cools the plant by evaporation. With insufficient water, plant growth/development is inhibited and if is great enough, the plant dies. –Almost all water a plant takes in comes from the soil through the roots.

© 2011, 2007, 2002, 1988 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ Practical Horticulture 5 th edition By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky tab Chapter 12 - Water Relations Water - Characteristics Water is the universal solvent; it dissolves more substances than any other liquid. Water is one of nature’s most stable compounds. –For centuries it was considered a single element, not the compound it is. The water molecule comprises two hydrogen atoms attached to one oxygen atom. (H 2 O)

© 2011, 2007, 2002, 1988 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ Practical Horticulture 5 th edition By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky tab Chapter 12 - Water Relations Water - Characteristics The water molecule is not symmetrical. Lack of symmetry creates a dipole with the molecule having more positive electrical charge, and the opposite end a more negative charge.

© 2011, 2007, 2002, 1988 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ Practical Horticulture 5 th edition By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky tab Chapter 12 - Water Relations Water - Characteristics Surface tension is a physical property of water. Molecules in the surface film in water are inwardly attracted, resulting in a strong surface tension. In the liquid state, attraction among water molecules is chaotic & random, but as it freezes, a symmetrical rigid lattice with an open porous structure forms. Water has an unusually high specific heat. Which allows it to absorb a large amount of heat without a large increase in temperature.