Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Chapter 37 Plant Nutrition 植物營養 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A Nutritional Network ( 營養網路 ) • Every organism is an open system connected to its environment by a continuous exchange of energy and materials. • In the energy flow and chemical cycling that keep an ecosystem alive, plants and other photosynthetic autotrophs perform the key step of transforming inorganic compounds into organic ones. • Plants need sunlight as the energy source for photosynthesis. And to synthesize organic matter, plants also require raw materials in the form of inorganic substances: carbon dioxide, water, and a variety of minerals present as inorganic ions in the soil. • With its ramifying root system and shoot system, a plant is extensively networked with its environment the soil and air, which are the reservoirs of the plants inorganic nutrients. • For a typical plant water and minerals come from the soil, while carbon dioxide (CO 2 ) comes from the air Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Key Concepts • Concept 37.1: Plants require certain chemical elements to complete their life cycle • Concept 37.2: Soil quality is a major determinant of plant distribution and growth • Concept 37.3: Nitrogen (N) is often the mineral that has the greatest effect on plant growth • Concept 37.4: Plant nutritional adaptations ( 營 養適應 ) often involve relationships with other organisms Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • The branching root system and shoot system of a vascular plant – Ensure extensive networking with both reservoirs of inorganic nutrients ( 無機營養 ) Figure 37.1 Root and shoot systems of a pea seedling Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Concept 37.1: Plants require certain chemical elements to complete their life cycle • Plants derive most of their organic mass from the CO 2 of air, but they also depend on soil nutrients such as water and minerals • Mineral nutrients Figure 37.2 CO 2 , the source of carbon for photosynthesis, diffuses into leaves from the air through stomata. Through stomata, leaves expel H 2 O and O 2 . H 2 O O 2 CO 2 Roots take in O 2 and expel CO 2 . The plant uses O 2 for cellular respiration but is a net O 2 producer. O 2 CO 2 H 2 O Roots absorb H 2 O and minerals from the soil. Minerals Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Functions of water in plants • Solvent in the cell • Photosynthetic reactant • Metabolic reactant or product • Respiration • Vacuolar content for cell elongation and extension • Turgor pressure • Others Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Macronutrients and Micronutrients 巨量營養素與微量營養素 • More than 50 chemical elements – Have been identified among the inorganic substances in plants, but not all of these are essential ( 必需的 / 必要的 ) • Essential elements ( 必需元素 ) – A chemical element is considered essential If it is required for a plant to complete a life cycle Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Hydroponic culture and essential elements( 水耕 法與必需元素 ) • Researchers use hydroponic culture ( 水耕法 ) to determine which chemicals elements are essential Figure 37.3 TECHNIQUE Plant roots are bathed in aerated solutions of known mineral composition. Aerating the water provides the roots with oxygen for cellular respiration. A particular mineral, such as potassium, can be omitted to test whether it is essential. RESULTS If the omitted mineral is essential, mineral deficiency symptoms occur, such as stunted growth and discolored leaves. Deficiencies of different elements may have different symptoms, which can aid in diagnosing mineral deficiencies in soil. Control: Solution containing all minerals Experimental: Solution without potassium (K + ) APPLICATION In hydroponic culture, plants are grown in mineral solutions without soil. One use of hydroponic culture is to identify essential elements in plants. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 17 essential elements=9 macro- and 8 micrnutrients • Nine of the essential elements are called macronutrients ( 巨量營養素 ), because plants require them in relatively large amounts – C, O, H, N, S, P, K, Ca • The remaining eight essential elements are known as micronutrients ( 微量營養素 ) – Because plants need them in very small amounts – Cl, Fe, B, Mn, Zn, Cu, Mo, Ni Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Essential elements in plants Table 37.1 ♦ ♦ [...]... Depend on the mobility of a nutrient within the plant – Chlorosis ( 黃化現象 ) • Deficiency of a mobile nutrient ( 移動力強的元素 ) – Mg – Usually affects older organs more than young ones – Drawing power ( 汲取力 ) is stronger in young organs • Deficiency of a less mobile nutrient ( 移動力弱的元素 ) – Fe – Usually affects younger organs more than older ones Copyright © 2005 Pearson Education, Inc publishing as Benjamin Cummings... – Are often visible in vertical profile ( 垂直剖面 / 斷 面 ) where there is a road cut or deep hole A The A horizon is the topsoil, a mixture of broken-down rock of various textures, living organisms, and decaying organic matter B C The B horizon contains much less organic matter than the A horizon and is less weathered ( 風化程度 ) The C horizon, composed mainly of partially broken-down rock, serves as the “parent” . 移動力強的元素 ) – Mg – Usually affects older organs more than young ones – Drawing power ( 汲取力 ) is stronger in young organs • Deficiency of a less mobile nutrient ( 移動力弱的元素 ) – Fe – Usually affects. horizon is the topsoil, a mixture of broken-down rock of various textures, living organisms, and decaying organic matter. The B horizon contains much less organic matter than the A horizon and is