Book contents
- Frontmatter
- Contents
- Preface
- Part I Farming systems and their biological components
- Part II Physical and chemical environments
- Part III Production processes
- 8 Nitrogen processes
- 9 Water relations
- 10 Photosynthesis
- 11 Respiration and partitioning
- Part IV Resource management
- Part V Farming past, present, and future
- Species list
- Conversions and constants useful in crop ecology
- References
- Index
9 - Water relations
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface
- Part I Farming systems and their biological components
- Part II Physical and chemical environments
- Part III Production processes
- 8 Nitrogen processes
- 9 Water relations
- 10 Photosynthesis
- 11 Respiration and partitioning
- Part IV Resource management
- Part V Farming past, present, and future
- Species list
- Conversions and constants useful in crop ecology
- References
- Index
Summary
Plants grow by fixing, in photosynthesis, CO2 that diffuses into leaves from the atmosphere through open stomatal pores in leaf surfaces. An inevitable consequence is that water vapor evaporates from wet cell walls that surround sub-stomatal cavities and diffuses through stomates to drier air outside. Water loss must be controlled or replaced if the plant is to maintain turgor and metabolic activity. Water is also a primary reactant in photosynthesis but the proportion of water required by plants that is chemically incorporated in their structure, or is used to maintain their water content as they grow, is very small.
Crops differ significantly in rooting habit and thus in their ability to acquire water from soil. Owing to differences in epidermal wax and in size, frequency, and behavior of stomates, they also vary in their ability to control loss of water from leaves. Control of water loss is always made at the expense of CO2 uptake for growth. For crops, flow of water from the soil to the atmosphere through plants is accompanied by direct evaporation of water from soil, particularly when the surface is wet and unprotected by foliage. The discussion of plant and crop water relations presented in this chapter draws heavily on the information presented in Chapter 6 (Aerial environment) and is essential background to understanding the productivity and effective management of rainfed and irrigated crops presented in Chapters 13 and 14.
- Type
- Chapter
- Information
- Crop EcologyProductivity and Management in Agricultural Systems, pp. 229 - 261Publisher: Cambridge University PressPrint publication year: 2011