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Plant Physiology and Biochemistry BSCBO- 303 B.Sc. III YEAR Plant Physiology and Biochemistry DEPARTMENT OF BOTANY SCHOOL OF SCIENCES UTTARAKHAND OPEN UNIVERSITY PLANT PHYSIOLOGY AND BIOCHEMISTRY BSCBO-303 Expert Committee Prof. J. C. Ghildiyal Prof. G.S. Rajwar Retired Principal Principal Government PG College Government PG College Karnprayag Augustmuni Prof. Lalit Tewari Dr. Hemant Kandpal Department of Botany School of Health Science DSB Campus, Uttarakhand Open University Kumaun University, Nainital Haldwani Dr. Pooja Juyal Department of Botany School of Sciences Uttarakhand Open University, Haldwani Board of Studies Prof. Y. S. Rawat Prof. C.M. Sharma Department of Botany Department of Botany DSB Campus, Kumoun University HNB Garhwal Central University, Nainital Srinagar Prof. R.C. Dubey Prof. P.D.Pant Head, Department of Botany Director I/C, School of Sciences Gurukul Kangri University Uttarakhand Open University Haridwar Haldwani Dr. Pooja Juyal Department of Botany School of Sciences Uttarakhand Open University, Haldwani Programme Coordinator Dr. Pooja Juyal Department of Botany School of Sciences Uttarakhand Open University Haldwani, Nainital UTTARAKHAND OPEN UNIVERSITY Page 1 PLANT PHYSIOLOGY AND BIOCHEMISTRY BSCBO-303 Unit Written By: Unit No. 1. Dr. Urmila Rana 1 & 2 Asst. Professor, Department of Botany, Pauri Campus, H.N.B. Garhwal University, Pauri, Uttarakhand 2. Dr. Shweta Kukreti 3 Asst. Professor, Department of Botany, Pauri Campus, H.N.B. Garhwal University, Pauri, Uttarakhand 3- Dr. Nishesh Sharma 4 Asst. Professor, Department of Biotechnology, Uttaranchal College of Applied and Life Science Uttaranchal University, Dehradun 4. Dr. Deepika Upadhyay 5 & 6 Asst. Professor, Department of Microbiology Chinmaya Degree College, BHEL, Haridwar 5- Dr. Manish Belwal 7 & 8 Asst Prof., Department of Botany Govt. Post Graduate College Gopeshwar (Chamoli) 6. Dr. Vivek Kumar Kedia 11 Asst Prof., Department of Botany Govt. Degree College Talwari Tharali, Chamoli-246482 7. Dr. Subhash Chandra 9, 10 & 12 Asst. Professor, Department of Botany, SSJ Campus, Kumaun University, Almora, Nainital, Uttarakhand Course Editor UTTARAKHAND OPEN UNIVERSITY Page 2 PLANT PHYSIOLOGY AND BIOCHEMISTRY BSCBO-303 Prof. J.C. Ghildiyal Principal, Govt. PG College, Karanprayag, Chamoli Title : Plant Physiology and Biochemistry ISBN No. : Copyright : Uttarakhand Open University Edition : Published By: Uttarakhand Open University, Haldwani, Nainital-263139 UTTARAKHAND OPEN UNIVERSITY Page 3 PLANT PHYSIOLOGY AND BIOCHEMISTRY BSCBO-303 BSCBO-303 PLANT PHYSIOLOGY AND BIOCHEMISTRY SCHOOL OF SCIENCES DEPARTMENT OF BOTANY UTTARAKHAND OPEN UNIVERSITY Phone No. 05946-261122, 261123 Toll free No. 18001804025 Fax No. 05946-264232, E. mail [email protected] htpp://uou.ac.in UTTARAKHAND OPEN UNIVERSITY Page 4 PLANT PHYSIOLOGY AND BIOCHEMISTRY BSCBO-303 CONTENTS BLOCK-1 PLANT WATER RELATIONSHIP PAGE NO. Unit-1- Absorption of water and Ascent of sap 7-38 Unit-2- Loss of water from plants 39-58 Unit-3- Mineral nutrition and Absorption of mineral salts 59-77 Unit-4- Organic substances- their Transport and Translocation 78-97 BLOCK-2 METABOLISM PAGE NO. Unit-5- Photosynthesis 99-131 Unit-6- Respiration 132-157 Unit-7- Nitrogen metabolism 158-181 Unit-8- Growth and Phases of development 182-214 BLOCK-3 BIOCHEMISTRY PAGE NO. Unit-9-Carbohydrates and Lipids 216-244 Unit-10-Proteins, Amino acids and Vitamins 245-279 Unit-11-Enzymology 280-299 Unit-12-Biochemical techniques 300-317 UTTARAKHAND OPEN UNIVERSITY Page 5 PLANT PHYSIOLOGY AND BIOCHEMISTRY BSCBO-303 BLOCK-1: PLANT - WATER RELATIONSHIP UTTARAKHAND OPEN UNIVERSITY Page 6 PLANT PHYSIOLOGY AND BIOCHEMISTRY BSCBO-303 UNIT-1: ABSORPTION OF WATER AND ASCENT OF SAP 1.1 Objectives 1.2 Introduction 1.3 Importance of water to plant life 1.4 Physical properties of water 1.5 Diffusion and Osmosis 1.6 Absorption of water 1.7 Ascent of sap 1.8 Summary 1.9 Glossary 1.10 Self Assessment Question 1.11 References 1.12 Suggested Readings 1.13 Terminal Questions UTTARAKHAND OPEN UNIVERSITY Page 7 PLANT PHYSIOLOGY AND BIOCHEMISTRY BSCBO-303 1.1 OBJECTIVES After reading this unit students will be able: To study the plant water relations and physical properties of water. To study physical processes of water, diffusion, osmosis, absorption of water and factors affecting water absorption process. To study the ascent of sap and its mechanism. 1.2 INTRODUCTION Water is an important factor for plant growth as it helps to fulfill all the vital activities of plants. Water is essential for photosynthesis, respiration, absorption of minerals and nutrients, metabolism and even to maintain the soil temperature too. Beside this, water is also important in various other processes too, as it helps in the germination of seeds and in the process of transpiration etc. Water helps a plant by transporting nutrients through the roots. Nutrients are drawn from the soil and used by the plant. Without enough water in the cells, the plants droop so water helps a plant stand. Water carries the dissolved sugar and other nutrients through the roots. Plants absorb water through their entire surface- roots, stems and leaves. However, the majority of water is absorbed by root hairs. To maintain the level of water inside the plant cells, it is necessary, to loss excess water from plant cells either in the form of evaporation or through transpiration. Evaporation of water from leaves is primarily controlled by stomata, sometimes lenticels and pores also helps in this process. This shows that, plants have a strong and significant relationship with water. Plant water relation means plants control the hydration of their cells including the collection of water from the soil, its transport within the plants and its loss by evaporation from the leaves. Transpiration also includes a process called guttation, which is the loss of water in liquid form from the uninjured leaf or stem of the plant principally through water stomata known as hydathodes. Studies have revealed that about 10 percent of the moisture found in the atmosphere is releases by plants through transpiration. 1.3 IMPORTANCE OF WATER TO PLANT LIFE Water is most important and prime factor for life processes, as life itself has been originated in an aqueous environment. In course of evolution it became fully dependent on water in a number of ways. Thus we can say that water is the liquid of life or elixir of life. In general water is essential for life and is the main constituent of the protoplasm comprising 90 to 95% of its total weight. In absence of water, protoplasm becomes inactive and even killed. Water is a source of hydrogen atoms for the reduction of carbon dioxide in the reaction of photosynthesis and as mentioned earlier that water helps to fulfill different vital activities. Beside this water present in the vacuoles which helps in maintaining the turgidity of cells which is essential for proper UTTARAKHAND OPEN UNIVERSITY Page 8 PLANT PHYSIOLOGY AND BIOCHEMISTRY BSCBO-303 activities of life. Due to absorption of water the cell becomes turgid. The turgidity of cell helps in the elongation of cells resulting in growth. It is a well- known fact that the availability of water during winter and summer season is different and is the reason of formation of annual rings in higher plants. In summer the turgidity is less and hence formation of small cells, comparatively to winter when due to higher turgidity, formation of larger cells takes place. In nature we have different type plants e.g. aquatic, terrestrial, halophytes, xerophytes etc. and different plants absorb water in different ways. While orchids, absorb moisture directly from the atmosphere and not from soil. Land plants get their water supply from soil which serves as the source of water and minerals to them. The way in which water from soil enters into roots, particularly to root xylem is called “Mechanism of water absorption‖ 1.4 PHYSICAL PROPERTIES OF WATER As per studies on global water covers about 73% of earth‘s surface and provides the most extensive medium for all aquatic life because of its unique properties from ecological point of view. Water occurs in in all three physical forms in the earth at moderate temperature. It is present in either in the form of fresh water or in saline water form in sea and salt lakes. The fresh water of active ground water, glaciers and ice caps, rivers, lakes dams, streams, soil moisture etc. represents only 1.92% of the total water stock. But even from this small segment as much as 98.65% is shared between active ground water and ice on mountain tops and poles, lakes and rivers constitute only 0.98% and 0.004% fresh water stock respectively. Fig. 1.1 Different states of matter UTTARAKHAND OPEN UNIVERSITY Page 9 PLANT PHYSIOLOGY AND BIOCHEMISTRY BSCBO-303 Fig.1.2 Water Cycle in the Atmosphere Water Structure and Properties: Water comprises over about 90% of the chemical content of many organisms and so we can say justifiably that water is the fluid of life but before this it is necessary to understand the different physiological processes related to the diffusion and absorption of water, and fundamental chemical and physical properties of water and its interaction with other substances. Water participates in all metabolic reactions either directly or indirectly. Water is a remarkable compound with unique properties that results from its molecular configuration and hydrogen bonding. Molecular Structure of Water: A single water molecule is composed of two hydrogen atoms bonded covalently to one side of an oxygen atom. Water absorbs large quantity of heat and tolerates other physical stresses without breakage of the bonds. Water is a polar inorganic compound at the room temperature at room temperature associates with each other because of the asymmetrical distribution hence due to these association i.e. adhesion or cohesion that are critical to the movement of water in soils and the translocation of water in plants.
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