basic terminology of plant physiology.pptx

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1. Introduction & Basic terminology of Physiology ACP-5121 Divedi Prasad Assistant professor ( Agronoomy ) SKSCARS, Rajnandgaon

2. INTRODUCTION   Physiology: Physiology is the study of functional aspects of crop plants. Crop physiology: Crop physiology is concerned with the processes and functions of the crops at cellular, sub-cellular and whole plant levels in response to environmental variables and growth.

3. PLANT KINGDOM CLASSIFICATION

4. Phyllum :  Bryophyta They are non-vascular land plants, which do not contain any conducting tissues and are often referred to as bryophytes.  These plants are small, grow close to the ground and include mosses and liverworts. They are very small in structure and are considered as important members of our ecosystem. The reproduction process is carried in their spores. They are non flowering plant and are found mainly growing on the ground, on other plants and on rocks. They play a vital role in preventing soil erosion. Examples: Mosses, Liverworts and  Hornworts.

5. Phyllum   Pteridophytae They are seedless vascular plants, which contain vascular tissues but do not produce seeds.   They are involved in transportation of fluids. The reproduction process is carried by spores. Examples: horsetails, ferns and club mosses

6. Phyllum :  Angiosperms Angiosperms are flowering plants, which develops the seeds within a protective structure. The reproduction process is carried by Angiosperm. They develop their seeds within an ovary, which itself is embedded in a flower. After the stage of fertilization, the flower falls and the ovary bulges to become a fruit. An angiosperms leaf consists of a single, branched, main vein, which originates from the base of the leaf blade. In few plats, it may also consist of four or more main veins diverging from the same base. Examples: trees, shrubs, vines and flowers.

7. Phyllum  Gymnosperms Gymnosperms are non-flowering plants with undeveloped seeds, which are present in an enclosed structure. Monocot begins with a single seed-leaf.  The main veins of their leaves are usually parallel and unbranched.  Monocot plays an important role in providing us with our primary sources of nutrition, which includes grains, fruits, etc. Examples: palms, carpet lawns, etc.

8. PHOTOSYNTHESIS Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that can later be released to fuel the organisms activities ( energy transformation ). This chemical energy is stored in carbohydrate molecules, such as sugars, which are synthesized from carbon dioxide and water. In most cases, oxygen is also released as a waste product. 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2

9. Photoautotroph Most plants, most algae, and cyanobacteria perform photosynthesis such organisms are called photoautotrophs. Chemoautotrophs Chemoautotrophs use inorganic energy sources such as hydrogen sulfide , elemental sulfur , ferrous iron, molecular hydrogen, and ammonia. Most chemoautotrophs are extremophiles, bacteria or archaea that live in hostile environments (such as deep sea vents) and are the primary producers in such ecosystems.

10. Cell A cell is the smallest unit of life. Cells are often called the "building blocks of life". The study of cells is called cell biology. Cells consist of cytoplasm enclosed within a membrane, which contains many bio-molecules such as proteins and nucleic acids. Cell contain a nucleus, a cytoplasm, and sub cellular organelles, and they are enclosed in a membrane that defines their boundaries. .

11. Eukaryote: Organism composed of one or more cells with a distinct nucleus and cytoplasm. Includes all forms of life except viruses and prokaryotes (Bacteria and Archaea ). Prokaryote: Single-celled microorganism whose cells lack a well-defined, membrane enclosed nucleus. The prokaryotes comprise two of the major domains of living organisms—the Bacteria and the Archaea .

12. PROKARYOTIC CELL

13. EUKARYOTIC CELL

14. PLANT CELLWALL

15. Cell wall: A rigid layer of polysaccharides lying outside the plasma membrane of the cells of plants, fungi, and bacteria. In the algae and higher plants it consists mainly of cellulose Primary cell wall: The primary cell wall is the part or layer of cell wall in which cell growth is permitted. Compared to secondary cell wall, this layer contains more pectin and lignin is absent until a secondary wall has formed on top of it. Compare: secondary cell wall, middle lamella. Secondary cell wall: The secondary cell wall is a structure found in many plant cells, located between the primary cell wall and the plasma membrane. The cell starts producing the secondary cell wall after the primary cell wall is complete and the cell has stopped expanding. Secondary cell walls owe their strength and toughness to lignin, a brittle, glue-like material.

16. Middle Lamella: The middle lamella is a pectin layer which cements the cell walls of two adjoining plant cells together. It is the first formed layer which is deposited at the time of cytokinesis . The cell plate that is formed during cell division itself develops into middle lamella or lamellum . Cell Membrane: The semipermeable membrane surrounding the cytoplasm of a cell. Also known as plasma membrane.

17. Nucleus: The nucleus is an organelle found in eukaryotic cells. Inside its fully enclosed nuclear membrane, it contains the majority of the cell's genetic material. This material is organized as DNA molecules, along with a variety of proteins, to form chromosomes. Plastid: A plastid is a self-reproducing organelle of plants and algae. A plastome is the DNA genome of a plastid. They are like tiny machines inside cells: each makes or stores important chemicals used by the plant. Chloroplast: a plastid in green plant cells which contains chlorophyll and in which photosynthesis takes place. Chlorophyll: Chlorophyll (also chlorophyll) is any of several related green pigments found in cyanobacteria and the chloroplasts of algae and plants. Its name is derived from the Greek words chloros ("green") and phyllon ("leaf").

18. Mitochondria: Mitochondria are organelles, or parts of a eukaryote cell. They are in the cytoplasm, not the nucleus. They make most of the cell's supply of adenosine triphosphate ( ATP ), a molecule that cells use as a source of energy. Their main job is to convert energy. They  oxidise glucose  to provide energy for the cell. The process makes ATP, and is called cellular respiration. So, mitochondria are known as "the power house of the cell". ATP: Adenosine triphosphate (ATP) is a complex organic chemical that participates in many processes. Found in all forms of life, ATP is often referred to as the "molecular unit of currency" of intracellular energy transfer. Endoplasmic reticulum: A network of membranous tubules within the cytoplasm of a eukaryotic cell, continuous with the nuclear membrane. It usually has ribosomes attached and is involved in protein and lipid synthesis.

19. MITOCHONDRIA

20. Ribosomes : A minute particle consisting of RNA and associated proteins found in large numbers in the cytoplasm of living cells. They bind messenger RNA and transfer RNA to synthesize polypeptides and proteins. Golgi body: A complex of vesicles and folded membranes within the cytoplasm of most eukaryotic cells, involved in secretion and intracellular transport. Vacuole ( Tonoplast ): A vacuole is a membrane-bound organelle. Vacuoles are closed sacs, made of membranes with inorganic or organic molecules inside, such as enzymes. They have no set shape or size, and the cell can change them as it wants. They are in most eukaryotic cells and do many things. They can store waste. Peroxisome: A small organelle present in the cytoplasm of many cells, which contains the reducing enzyme catalase and usually some oxidases.

21. RIBOSOMES

22. Metabolism: The chemical processes that occur within a living organism in order to maintain life and consists of Anabolism and Catabolism. Anabolism: The synthesis of complex molecules in living organisms from simpler ones together with the storage of energy; constructive metabolism. Photosynthesis is an anabolic process. Catabolism: Catabolism (from Greek kato , "downward" and ballein , "to throw") is the set of metabolic pathways that breaks down molecules into smaller units that are either oxidized to release energy or used in other anabolic reactions. Respiration is a catabolic process. Respiration: A process in living organisms involving the production of energy, typically with the intake of oxygen and the release of carbon dioxide from the oxidation of complex organic substances.

23. Photorespiration: A respiratory process in many higher plants by which they take up oxygen in the light and give out some carbon dioxide, contrary to the general pattern of photosynthesis. Glycolysis: Glycolysis can be defined as the sequence of reactions for the breakdown of Glucose (6-carbon molecule) to two molecules of pyruvic acid (3-carbon molecule) under aerobic conditions; or lactate under anaerobic conditions along with the production of small amount of energy.

24. Tissue: In biology, tissue is a cellular organizational level between cells and a complete organ. A tissue is an ensemble of similar cells and their extracellular matrix from the same origin that together carry out a specific function. Organs are then formed by the functional grouping together of multiple tissues. Plant Organ Systems: A plant has two  organ systems : the  shoot  system, and the  root  system. The shoot system is above ground and includes the organs such as leaves, buds, stems, flowers (if the plant has any), and fruits (if the plant has any). The root system includes those parts of the plant below ground, such as the roots,  tubers , and  rhizomes .

25. Stem: A stem is one of two main structural axes of a vascular plant, the other being the root. The stem is normally divided into nodes and internodes: The nodes hold one or more leaves, as well as buds which can grow into branches (with leaves, conifer cones, or inflorescences (flowers)) Nodes: The stem is normally divided intonodes  and internodes: The nodes hold one or more leaves, as well as buds which can grow into branches (with leaves, conifer cones, or inflorescences (flowers)). Leaf: A leaf is an organ of a vascular plant and is the principal lateral appendage of the stem. The leaves and stem together form the shoot. Leaves are collectively referred to as foliage, as in "autumn foliage". Diagram of a simple leaf. Apex; Midvein (Primary vein); Secondary vein. Lamina. Leaf margin; Petiole; Bud; Stem. Meristem: A meristem is the tissue in most plants containing undifferentiated cells ( meristematic cells), found in zones of the plant where growth can take place. Meristematic cells give rise to various organs of the plant and keep the plant growing.

26. Leaf primordia : The shoot apical meristem (SAM), at the tip of the plant stem, has two roles; it is the source of the new cells that are needed for stem growth, and it is the site of small cellular outgrowths, called leaf primordial (LP), that develop into the leaves. Flower: A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division  Magnoliophyta , also called angiosperms). The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs. Flowers may facilitate outcrossing (fusion of sperm and eggs from different individuals in a population) or allow selfing (fusion of sperm and egg from the same flower).  Fruit: In botany, a fruit is the seed-bearing structure in flowering plants (also known as angiosperms) formed from the ovary after flowering.

27. Tap root: A taproot is a large, central, and dominant root from which other roots sprout laterally.  Adventitious root : Some roots, called adventitious roots, arise from an organ other than the root—usually a stem, sometimes a leaf. They are especially numerous on underground stems. The formation of adventitious roots makes it possible to vegetatively propagate many plants from stem or leaf cuttings. Lateral roots: Lateral roots extend horizontally from the primary root (radicle) and serve to anchor the plant securely into the soil. This branching of roots also contributes to water uptake, and facilitates the extraction of nutrients required for the growth and development of the plant. Root hairs: each of a large number of elongated microscopic outgrowths from the outer layer of cells in a root, absorbing moisture and nutrients from the soil. Root cap: The root cap is a section of tissue at the tip of a plant root. It is also called calyptra

28. Parenchyma: A generalized plant cell type, parenchyma cells are alive at maturity. They function in storage, photosynthesis, and as the bulk of ground and vascular tissues. Palisade parenchyma cells are elongated cells located in many leaves just below the epidermal tissue. Aerenchyma : Aerenchyma  is a spongy tissue that forms spaces or air channels in the leaves, stems and roots of some plants, which allows exchange of gases between the shoot and the root. The channels of air-filled cavities (see image to right) provide a low-resistance internal pathway for the exchange of gases such as oxygen and ethylene between the plant above the water and the submerged tissues. Aerenchyma is also widespread in aquatic and wetland plants which must grow in hypoxic soils.

29. Primary growth: The phase of plant development that gives rise to new organs and to the basic plant form is called primary growth. Secondary growth: After elongation in a given region is complete, secondary growth may occur. Secondary growth involves two lateral meristems : the vascular cambium (plural cambia) and the cork cambium. The vascular cambium gives rise to secondary xylem (wood) and secondary phloem. The cork cambium produces the periderm, consisting mainly of cork cells. Vascular tissue: Vascular tissue is a complex conducting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem. These two tissues transport fluid and nutrients internally. Xylem: Xylem is one of the two types of transport tissue in vascular plants, phloem being the other. The basic function of xylem is to transport water from roots to shoots and leaves, but it also transports some nutrients.

30. Phloem: In vascular plants, phloem is the living tissue that transports the soluble organic compounds made during photosynthesis and known as  photosynthates , in particular the sugar sucrose, to parts of the plant where needed.  Translocation : Translocation  is the movement of materials from leaves to other tissues throughout the plant. Plants produce carbohydrates (sugars) in their leaves by photosynthesis, but non-photosynthetic parts of the plant also require carbohydrates and other organic and nonorganic materials. Transpiration: Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves , stems and flowers. Water is necessary for plants but only a small amount of water taken up by the roots is used for growth and metabolism. Reverse transpiration: The significance of the vapor pressure decrease to leaf gas exchange and its implications for possible foliar water uptake by “reverse transpiration”.

31. Evapotranspiration : The process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants. Stomata: In botany, a stoma (plural "stomata"), also called a  stomate  (plural " stomates ") (from Greek, "mouth"), is a pore, found in the epidermis of leaves, stems, and other organs, that facilitates gas exchange. The pore is bordered by a pair of specialized parenchyma cells known as  guard cells  that are responsible for regulating the size of the stomatal opening. Guard cells: Guard cells are cells surrounding each stoma. They help to regulate the rate of transpiration by opening and closing the stomata.

32. Hypoxia: Deficiency in the amount of oxygen reaching the tissues. Anoxia: An absence or deficiency of oxygen reaching the tissues; severe hypoxia . Hyperoxia : Hyperoxia  occurs when cells, tissues and organs are exposed to an excess supply of oxygen (O 2 ) or higher than normal partial pressure of oxygen.

33. Water and importance to plants: Water has special properties that enable it to act as a solvent and to be readily transported through the body of the plant. These properties derive primarily from the polar structure of the water molecule. Water is the main constituent of protoplasm comprising up to about 90-95 per cent of its total weight. Different organic constituents of plants such as carbohydrates proteins, nucleic acid and enzymes etc. Lose their physical and chemical properties in the absence of water. Water participates directly in many metabolic processes. Inter conversion of carbohydrates and organic acids depend upon hydrolysis and condensation reaction.

34. Water increases the rate of respiration. Seeds respire fast in the presence of water. Water is the source of hydrogen atom for the reduction of CO2 in the reaction of photosynthesis. Water acts as a solvent and acts as a carrier for many substance. If forms the medium in which several reactions take place. Water present in the vacuoles helps in maintaining the turgidity of the cells which is a must for proper activities of life and to maintain this from and structure. Water helps in translocation of solutes. In tropical plants, water plays a very important role of thermal regulation against high temperature. The elongation phase of cell growth depends on absorption of water. For every gram of organic matter made by the plant, approximately 500 g of water is absorbed by the roots, transported through the plant body and lost to the atmosphere.

35. Osmosis: The diffusion of solvent molecules into the solution through a semi permeable membrane is called as osmosis (sometimes called as Osmotic diffusion). In case there are two solutions of different concentration separated by the semi permeable membrane, the diffusion of solvent will take place from the less concentrated suitable into the more concentrated solution till both the solutions attain equal concentration. Osmotic pressure: As a result of the separation of solution from its solvent (or) the two solutions by the semi permeable membrane, a pressure is developed in solution to the pressure by dissolved solutes in it. This is called as osmotic pressure (O.P). End-osmosis: Of a living plant cell is placed in water or hypotonic solution whose O.P is lower than cell sap, water in-terms into the cell sap by osmosis and the process is called end osmosis.

36. Exosmosis : If on the other hand, the plant cell is placed in hypertonic solution (whose O.P is higher than cell sap) the water cover out the cell sap into the outer solution and the cell becomes flaccid. This process is known as exosmosis . Plasmolysis : When a plant cell or tissue is placed in a hypertonic solution water cover out from the cell sap into the outer solution of exosmosis and the protoplasm begins to sprinkler or contract. The protoplasm separate from the cell wall and assures a spherical form and them phenomenon is called plasmolysis . It indicates the semi permeable nature of the plasma membrane. It is used in determine the osmotic pressure of the cell sap. Plasmolysis is used in salting of meat and fishes.

37. Hypotonic solution: A hypotonic solution is any solution that has a lower osmotic pressure than another solution. In the biological fields, this generally refers to a solution that has less solute and more water than another solution. Isotonic solution: An isotonic solution refers to two solutions having the same osmotic pressure across a semipermeable membrane. Hypertonic solution: A hypotonic solution is one in which the concentration of solutes is greater inside the cell than outside of it, and a hypertonic solution is one where the concentration of solutes is greater outside the cell than inside it. Imbibition: Certain substances ( Imbibant ) if placed in a particular liquid absorb it and swell up. This phenomenon is called Imbibition.

38. Field capacity or water holding capacity of the soil: After heavy rain fall or irrigation of the soil some water is drained off along the slopes while the rest percolates down in the soil. Out of this water, some amount of water gradually reaches the water table under the force of gravity (gravitational water) while the rest is retained by the soil. This amount of water retained by the soil is called as field capacity or water holding capacity of the soil. Field capacity is affected by soil profiles soil structure and temperature. Water-holding capacity is controlled primarily by soil texture and organic matter. At field capacity, the soil water potential is –0.1 to –0.3 bars.

39. Water potential: Every component of a system possesses free energy capable of doing work under constant temperature conditions. For non-electrolytes, free energy / mole is known as chemical potential. With refuse to water, the chemical potential of water is called as water potential. The chemical potential is denoted by a Greek letter Psi (ψ). Water potential is the potential energy of water relative to pure free water (e.g. deionized water) in reference conditions. It quantifies the tendency of water to move from one area to another due to osmosis, gravity, mechanical pressure, or matrix effects including surface tension. For pure water, the water potential is Zero. The presence of solute particles will reduce the free energy of water or decrease the water potential. Therefore it is expressed in vegetative value. It is therefore, water potential of solution is always less than zero so in negative value. For solutions, water potential is determined by three internal factors i.e. Ψ w = Ψ m + Ψs + Ψp

40. Ψ w = Ψ m + Ψs + Ψp Ψs = is the solute potential or osmotic potential Ψp = pressure potential or turgor potential Ψ m = is the matric potential. Matric potential can be measured for the water molecules adhering on the soil particles and cell wall. In plant system, the matric potential is disregarded. Therefore, Ψ w = Ψs + Ψp

41. Osmotic pressure: Osmotic pressure is equivalent to osmotic potential but opposite in sign. Osmotic pressure in a solution results due to the presence of solutes and the solutes lower the water potential. Therefore osmotic pressure is a quantitative index of the lowering of water potential in a solution and using thermodynamic terminology is called as osmotic potential. Osmotic pressure and osmotic potential are numerically equal but opposite in sign. Osmotic pressure has positive sign Osmotic potential has negative sign ( ψs )

42. Turgor pressure: In plant cell, the turgor pressure results due to the presence of water molecules is turgor pressure. The potential created by such pressures is called pressure potential ( ψp ) In a normal plant cell, the water potential ψ w = ψ s + ψ p – partially turgid cell (High) ψ w = Zero - Fully turgid cell (Highest) ψ w = ψ s - Flaccid cell or plasmolysed cell (Lowest)

43. Diffusion Pressure Deficit (Suction pressure): Diffusion pressure of a solution is always lower than its pure solvent. The difference between the diffusion pressure of the solution and its solvent at a particular temperate and atmosphere conditions is called as diffusion pressure deficit (D.P.D). If the solution is more concentrated D.P.D increases but it decreases with the dilution of the solution. D.P.D of the cell sap or the cells is a measure of the ability of the cells to absorb water and hence is often called as the suction pressure (S.P). It is related with osmotic pressure (O.P) and turgor pressure (T.P) of cell sap and also the wall pressure (W.P) as follows. D.P.D. (S.P) = O.P – W.P But (W.P) = T.P D.P.D = O.P – T.P

44. Due to the entry of the water the osmotic pressure of the cell sap decreases while its turgor pressure is increased so much so that in a fully turgid cell T.P equals the O.P O.P = T.P = D.P.D = O In fully plasmolysed cells: T.P = O So D.P.D = O.P Entry of water into the cell depends on D.P.D and not on O.P only

45. ABSORPTION OF WATER – MODE OF WATER ABSORPTION – ACTIVE AND PASSIVE ABSORPTION AND FACTORS AFFECTING ABSORPTION

46. Solute potential: Pure water is usually defined as having a solute potential of zero, and in this case, solute potential can never be positive. The relationship of solute concentration (in molarity) to solute potential is given by the van't Hoff equation: = miRT Where m - The concentration in molarity of the solute, i - The van 't Hoff factor, the ratio of amount of particles in solution to amount of formula units dissolved, R - The ideal gas constant, and T is the absolute temperature.

47. WATER MOVEMENT MECHANISM IN PLANTS

48. In plants, following two pathways are involved in the water movement. They are (1) Apoplastic pathway (2) Symplastic pathway (3) Transmembrane pathway Apoplastic pathway: The apoplastic movement of water in plants occurs exclusively through the cell wall without crossing any membranes. The cortex receive majority of water through apoplastic way as loosely bound cortical cells do not offer any resistance. But the movement of water in root beyond cortex apoplastic pathway is blocked by casparian strip present in the endodermis.

49. Symplastic pathway: The movement of water from one cell to other cell through the plasmodesmata is called the symplastic pathway of water movement. This pathway comprises the network of cytoplasm of all cells inter-connected by plasmodermata . Transmembrane pathway: In plant roots, water movement from soil till the endodermis occurs through apoplastic pathway i.e. only through cell wall. The casparian strips in the endodermis are made-up of wax -like substance suberin which blocks water and solute movement through the cell wall of the endodermis. As a result water is forced to move through cell membranes and may cross the tonoplast of vacuole. This movement of water through cell membranes is called transmembrane pathway.

50. Active absorption of water: In this process the root cells play active role in the absorption of water and metabolic energy released through respiration is consumed active absorption may be of two kinds. Osmotic absorption: Water is absorbed from the soil into the xylem of the roots according to osmotic gradient. Non-osmotic absorption: Water is absorbed against the osmotic gradient. Sometimes, it has been observed that absorption of water takes place even when OP of soil water is high than OP of cell sap. This type of absorption which is non-osmotic and against the osmotic gradient requires the expenditure of metabolic energy probably through respiration. Passive absorption of water: It is mainly due to transpiration, the root cells do not play active role and remain passive.

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