tailieunhanh - Plant physiology - Chapter 4 Water Balance of Plants

LIFE IN EARTH’S ATMOSPHERE presents a formidable challenge to land plants. On the one hand, the atmosphere is the source of carbon dioxide, which is needed for photosynthesis. Plants therefore need ready access to the atmosphere. On the other hand, the atmosphere is relatively dry and can dehydrate the plant. To meet the contradictory demands of maximizing carbon dioxide uptake while limiting water loss, plants have evolved adaptations to control water loss from leaves, and to replace the water lost to the atmosphere. In this chapter we will examine the mechanisms and driving forces operating on water transport within the. | Chapter 4 Water Balance of Plants LIFE IN EARTH S ATMOSPHERE presents a formidable challenge to land plants. On the one hand the atmosphere is the source of carbon dioxide which is needed for photosynthesis. Plants therefore need ready access to the atmosphere. On the other hand the atmosphere is relatively dry and can dehydrate the plant. To meet the contradictory demands of maximizing carbon dioxide uptake while limiting water loss plants have evolved adaptations to control water loss from leaves and to replace the water lost to the atmosphere. In this chapter we will examine the mechanisms and driving forces operating on water transport within the plant and between the plant and its environment. Transpirational water loss from the leaf is driven by a gradient in water vapor concentration. Long-distance transport in the xylem is driven by pressure gradients as is water movement in the soil. Water transport through cell layers such as the root cortex is complex but it responds to water potential gradients across the tissue. Throughout this journey water transport is passive in the sense that the free energy of water decreases as it moves. Despite its passive nature water transport is finely regulated by the plant to minimize dehydration largely by regulating transpiration to the atmosphere. We will begin our examination of water transport by focusing on water in the soil. WATER IN THE SOIL The water content and the rate of water movement in soils depend to a large extent on soil type and soil structure. Table shows that the physical characteristics of different soils can vary greatly. At one extreme is sand in which the soil particles may be 1 mm or more in diameter. Sandy soils have a relatively low surface area per gram of soil and have large spaces or channels between particles. At the other extreme is clay in which particles are smaller than 2 gm in diameter. Clay soils have much greater surface areas and smaller 48 Chapter 4 channels between particles. .

• Sinh học
• Mineral Nutrition
• Plant Cells
• Energy
• Enzymes
• Water Balance
• Plants
• Translocation
• Water and Solutes
• Mineral nutrients
• Root growth
• Root development
• Root growth of crop plants
• Role of mineral nutrition
• Genomic status
• Chemical and mineral composition
• Human nutrition
• Mineral composition
• Genomic groups grown in India
• Turkish Journal of Agriculture and Forestry
• Tạp chí Nông Lâm nghiệp
• Chromium toxicity in plants
• Chromosomal behavior
• Mineral nutrient status
• Plant growth and nutrition
• Root Absorption
• Soil Fungi
• Plant Interaction
• Plant Soil
• Microorganism Interactions
• Microorganism Interaction
• Abiotic Stress
• Phytoremediation
• Biofortification
• Nanoparticles
• Plant Antioxidative
• Báo cáo lâm nghiệp hay
• cách trình bày báo cáo
• báo cáo lâm nghiệp
• công trình nghiên cứu lâm nghiệp
• tài liệu về lâm nghiệp