|Alpert, Peter - UNIV. OF MASSACHUSETTS|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: February 1, 2002
Publication Date: N/A
Interpretive Summary: Interpretive summary not required.
Technical Abstract: Water is the most abundant compound in all active cells. It is essential for metabolism, and all organisms must take in water to survive. Living things therefore face a major problem whenever they emerge above ground on land: the air is almost always drier than they are and takes water from them. This is a life and death problem for most organisms in most habitats. .For example, when the relative humidity is about 50% and the temperature 2 deg C, a plant cell that dries to equilibrium will drop to a water potential of about -100 MPa. This kills over 99% of flowering plants. Terrestrial plants appear to have evolved two solutions to the problem of maintaining an aqueous self in a withering world. The majority solution, at least at the present evolutionary time, is never to dry out--to maintain a chronic disequilibrium between wet cells and dry air. The minority solution is to dry up but not die--to desiccate during drought and rehydrate and resume growth when drought ends. About 300 species of flowering plants, or perhaps 0.1% of those named, are known to tolerate desiccation. The purpose of this introductory chapter is to summarize some of the current answers to these questions and lead into the more detailed reviews of questions and answers about desiccation and plant survival in the chapters that follow.