1011 植的水分关系.ppt

Chapter1 Water Relationship in Plant;Section1 Role of water in plant life 1.1 Structure and physi-chemical characters of water 1.2 Water content and status in plant 1.3 Role of water in plant life;1.1 Structure and physi-chemical characters of water A.Water is a polar molecule with hydrogen bond between them B. High specific heat and latent heat of evaporation(高比热和高气化热) C. Great surface tension(大的表面张力) and cohesion(内聚力） D. High dielectric constant(高介电常数) and an extensive solvent (良好的溶剂);1.2 Water content and status in plant 1.2.1 Water content;Organs Stem tenders and root tips90% function leaves 70-90% tree stem 40-50% dormancy bud 40% wind-dried seeds 8-14% Growth environment shade plantssun plants Life activity the higher life activity, the higher water content;1.2.2 Status in plant Free water and bound water;In plant metabolic activity, growth situation and resistance are related to the ratio of free water to bound water. ? The higher F/B ratio, the higher metabolism and the faster growth, but lower resistance because protoplasm is nearer to sol. ? The lower ratio, the lower metabolism and the slower growth, but higher resistance because protoplasm is of nearer to gel.;1.3 Role of water in plant life (1) Component of protoplasm Protoplasm in plant contains 70-90% water. (2) Substrate(底物) for plant metabolism Photosynthesis, respiration and biosynthesis or degradation of organic substance. (3) Solvents for plant absorption and transportation (4) Keeping plant in shape (extension) (5) Balance plant temperature;Section 2 Water absorption by plant cell 2.1 Osmotic absorption of water by plant cell 2.2 Imbibing absorption of water by plant cell 2.3 Metabolic absorption of water by plant cell 2.4 Water channel proteins or aquaporins;2.1 Osmotic absorption of water by plant cell 2.1.1 Free energy, chemical potential and water Potential 2.1.2 Osmosis and osmotic potential 2.1.3 Plant cell is an osmotic system 2