Lecture 3 Plant nutrition.pdf

UNIVERSITY OF SOUTHERN MINDANAO Mineral Nutrition of Plants and Solute Transport Bio 312a General Physiology Topic Outline History and Introduction Nutrient uptake and Movement Essentiality of an Element Classification of Essential Elements Role of Es...

UNIVERSITY OF SOUTHERN MINDANAO Mineral Nutrition of Plants and Solute Transport Bio 312a General Physiology Topic Outline History and Introduction Nutrient uptake and Movement Essentiality of an Element Classification of Essential Elements Role of Essential Elements and their Deficiency Symptoms Solution Culture Technique: Hydroponics Role of Fertilizers Transport in the Phloem Pressure-flow Mechanism Insert Running Title 2 Intended Learning Outcomes 1. Discuss the plant root system and its interaction with the soil. 2. Discuss the nutritional needs of plants. 3. Describe the symptoms of specific nutritional deficiencies and the use of fertilizers to ensure proper plant nutrition 4. Explain the beneficial role of microorganisms with respect to nutrient uptake by roots. 5. Discuss the transport of molecules and its application to membranes and biological systems. 3 Insert Running Title Jan-Baptist van Helmont – 1648, plants immediately and materially arises from water alone.  Justus von Liebig Law of the Minimum productivity of the soil depends upon the proportionate amount of the deficient nutrient. 109 elements found in different plants 20 known to be essential 17 widely considered Jethru Tullessential Mineral Elements All elements except C, H and O They are derived from the weathering of parent rocks and held by the soil N is a mineral as well as non-mineral (atmospheric) Inorganic forms of N are NO3-, NO2-, and NH4+ Mineral Elements (Salts) Are distributed in soils either in: dissolved salts: form soil solution adsorbed minerals: held by soil colloids Not absorbed in molecular form but in ionic form (cations and anions) N occurs as cation (NH4+) and anions (NO3-, NO2-) K, Mg, Ca, Fe, Zn occur in cationic form P, S, B, Mo, Cl occur in anionic form  Nutrient Uptake REQUIRES TRANSPORT OF THE NUTRIENT ACROSS ROOT CELL MEMBRANES Therefore fundamentally a cellular problem, governed by the rules of membrane transport Three fundamental concepts: simple diffusion, facilitated diffusion, and active transport Simple Diffusion Concentration gradient Non-polar O2, CO2, NH3, H2O (Aquaporins) Ions, generally not permitted Fick’s law The rate at which molecules in solution diffuse from one region to another is a function of their concentration difference Cross sectional area of the diffusion path  MOVEMENT OF MOST SOLUTES ACROSS MEMBRANES REQUIRES THE PARTICIPATION OF SPECIFIC TRANSPORT PROTEINS Facilitated Diffusion Rapid, assisted diffusion of solutes across the membrane Follows: Concentration gradient (uncharged) Electrochemical potential gradient (charged) Channel proteins Carrier proteins Channel Proteins Normally identified by the ion species that is able to permeate the channel; dependent on the size of the hydrated ion and its charge. Dependent on the hydrated size of the ion K+, Cl−, and Ca2+ channels Frequently gated (they may be open or closed) 1. Electrically gated channel - membrane potentials of a particular The precise mechanism of gated magnitude. channels is not known, although it is 2. Open only in the presence of the ion presumed to involve a change in the that is to be transported may be modulated by light, three-dimensional shape, or hormones, or other stimuli. conformation, of the protein. Carrier Protein Bind the particular solute to be transported, much along the lines of an enzyme–substrate interaction. Binding of the solute normally induces a conformational change in the carrier protein, which delivers the solute to the other side of the membrane. Release of the solute at the other surface of the membrane completes the transport and the protein then reverts to its original conformation, ready to pick up another solute. Active Transport Tightly coupled to a metabolic energy source Requires an input of energy and does not occur spontaneously Unidirectional— either into or out of the cell Always mediated by carrier proteins Pump  Utilizes P type ATPases (ATPase-Proton pump) Found in plasma, vacuolar and other membranes Pumps H+ against gradient with the hydrolysis of ATP Establishes transmembrane potential/proton motive force Establishes chemiosmosis The proton pump (a) uses the energy of ATP to establish both a proton gradient and a potential difference (negative inside) across the membrane. The energy of the proton gradient may activate an ion channel (b) or drive the removal of ions from the cell by an antiport carrier (c), or drive the uptake of ions or uncharged solute by a symport carrier (d, e). Similar pumps and carriers operate across the vacuolar membrane. C+, cation; A−, anion; S, uncharged solute. Active transport Ion Movement Electrochemical gradient/Transmembran e potential Electrical potential Chemical potential Effect of pH on Nutrient Availability  Arnon and Stout Promulgated criteria of essentiality in 1939 Needed to complete the life cycle of the Essentiality plant Part of some essential plant constituent of an or metabolite Role cannot be replaced by other Element element Indispensable to the life of plants 17 Essential Elements Categorized according to quantity needed for normal plant growth Macronutrient; 0.1% or greater per dm or required at 1000 mg/kg of dm H, C, O, N, P, K, Ca, Mg, and S Some plants: Si Micronutrient; less than 1 ppm or required at less than 100 mg/kg of dm Cl, Fe, B, Mn, Zn, Cu, Mo, and Ni C HOPKNS CaFe Mn Mg B Cu Zn Mo Cl Chopkins café managed by my cousin MoCl  Beneficial elements Promote growth but not absolutely necessary for completion of life cycle Na – Atriplex vasicaria Si – Equisetum Co – legumes Se – Brassicas  Essential elements Classified Metals K, Ca, Mg, Fe, Mn, Zn, Ca, Mo, Ni Non-metals C, H, O, N, P, S, B, Cl Nutrient Disorders Mobile elements – move freely from one plant part to another Symptoms first show in older leaves Immobile elements – cannot be translocated; permanently stucked Adequate Levels of Essential Elements in Plants Available Forms of Essential Elements  Biological Significance of Mineral Elements 1. Structural Elements C, H, O take part in carbohydrate synthesis which constitute major part in cell wall and protoplasm S, P, N take part in protein synthesis Mg, N are constituents of Chlorophyll Ca constitutes the cell wall (as Calcium Pectate) P is a constituent of nucleo-protein 2. Elements with Functional Role a. Catalytic role Mn, Cl in photolysis of water Zn as cofactor of carbonic anhydrase Fe as cofactor of Cytochrome a and a3 Cu as cofactor of plastocyanin b. Permeability of membranes c. pH and buffer action d. Osmotic potential 3. Elements with Electrochemical Role Neutralize the toxic effect of other elements Ca, K, Mg and Si are balancing elements Mn in 300-400 ppm is toxic to barley but Si neutralizes  Mengel and Kirkby (1987) in their book: Principles of Plant Nutrition Classification into Proposed classification macroelements and based on biochemical role microelements is and physiological function: difficult to justify physiologically Omitted Carbon, Hydrogen and Oxygen  Group I: Part of Organic Group Compounds in Plants N and S Four Groups Group II: Important in energy Group storage or structural integrity of Essential P, B and Si Elements Acc to Mengel Group Group III: Remain in ionic form and Kirby K, Ca, Mg, Cl, Mn and Na Group IV: Involved in redox Group reactions Fe, Zn, Cu, Ni and Mo Nutrient Disorders Methods 1. Visual symptoms of deficiency and toxicity 2. Plant and Soil Analyses 3. Determination of biochemical indicators Enzyme activity; metabolic products  Nutrient Disorders Chlorosis General, interveinal, mottled (N, S, Mg, Fe, Mn) Necrosis Spot Interveinal Tip and marginal (K, B) Brittleness of stems and leaves (Mg) Deformation of bud and leaves (Ca, B) Stunted growth (rosetting) (Zn) Wilting (Cl) Inhibited root growth (Ni) Anthocyanin formation (P, N) Dark blue green leaves (P) Lodging Blossom-end rot Bronzing Whiptail disease  Chlorosis Chlorosis - A condition in which leaves produce insufficient amount of Chlorophyll ETIOLATION A process wherein plants are grown in partial or complete absence of light Seedlings have small, weak stems, sparser and yellow leaves Chlorophyll not synthesized  Necrosis Death of a living cell or tissue Rosetting/ Stunting of Growth Anthocyanin formation  Bronzing A nutritional disorder characterized by discoloration of leaf surfaces with reddish brown speckles Lodging Bending of the stalk (stem lodging) or entire plant (root lodging) Different causes: pest, large load, nutrient  a physiological problem characterized by a black lesion at the distal end of the fruit caused by adverse growing conditions (nutrient Blossom-end rot unavailability) rather than a pest or disease Whip tail disease Leaves become thin/narrow (straplike) and malformed Sometimes only midribs develop Role of Essential Elements and their Deficiency Symptoms Group 1: Mineral nutrients that are part of carbon compounds NITROGEN Required in greatest amount. It serves as a constituent of many plant cell components, including amino acids and nucleic acids. Therefore, deficiency rapidly inhibits plant growth. Most species show CHLOROSIS (yellowing of the leaves), especially in the older leaves near the base of the plant Slender, woody stems SULFUR Found in two amino acids Constituent of several coenzymes and vitamins essential for metabolism. Similar to those of nitrogen deficiency, including chlorosis, stunting of growth, and anthocyanin accumulation But chlorosis is more or less evenly distributed throughout the leaf (General chlorosis) Arises initially in young leaves, rather than in the old leaves Occasionally, occur simultaneously in all leaves or even initially in the older leaves Group 2: Mineral nutrients that are important in energy storage or structural integrity. PHOSPHORUS As phosphate, PO43– is an integral component of sugar–phosphate intermediates of respiration and photosynthesis, and phospholipids that make up plant membranes. Component of nucleotides used in plant energy metabolism (such as ATP) and in DNA and RNA. Deficiency Symptoms: stunted growth in young plants dark green coloration of the leaves which may be malformed and contain small spots of dead tissue called NECROTIC spots Anthocyanin formation but not associated to chlorosis Slender stems (but not woody) SILICON Only members of the family Equisetaceae - called scouring rushes because at one time their ash, rich in gritty silica, was used to scour pots Require silicon to complete their life cycle. Nonetheless, many other species accumulate silicon and show enhanced growth and fertility when supplied with adequate amounts Ameliorate heavy metal toxicity Deficiency symptoms include: Susceptibility to lodging (falling over) and fungal infection BORON Plays roles in cell elongation, nucleic acid synthesis, hormone responses, and membrane function Deficiency Symptoms: black necrosis of the young leaves and terminal buds primarily at the base of the leaf blade. Stems may be unusually stiff and brittle. Apical dominance may lost Apices of the branches become necrotic because of inhibition of cell division. Fruit, fleshy roots, and tubers may exhibit necrosis or abnormalities related to the breakdown of internal tissues. Causes hollow stem in cauliflower Group 3: Mineral nutrients that remain in ionic form  POTASSIUM Present within plants as the cation K+ Regulation of the osmotic potential of plant cells Activates many enzymes involved in respiration and photosynthesis Symptoms of potassium deficiency: Mottled or marginal chlorosis, which then develops into necrosis primarily at the leaf tips, at the margins, and between veins in mature leaves. In many monocots, these necrotic lesions may initially form at the leaf tips and margins and then extend toward the leaf base. Stems are slender and weak with short internodes Increased susceptibility to root-rotting fungi Increased tendency for the plant to be easily bent to the ground (lodging). CALCIUM Calcium ions (Ca2+) are used in the synthesis of new cell walls, particularly the middle lamellae. Used in the mitotic spindle during cell division. Normal functioning of membranes Second messenger for various plant responses to both environmental and hormonal signals (Calmodulin) Deficiency may cause: Youngest leaves remain rolled and joined together at their tips Necrosis of young meristematic regions, such as the tips of roots or young leaves (Tip burn) Blossom-end rot Necrosis may be preceded by general chlorosis and downward hooking and deformed young leaves Root system of a calcium-deficient plant may appear brownish, short, and highly branched. MAGNESIUM Activation of enzymes involved in respiration, photosynthesis, and the synthesis of DNA and RNA Part of the ring structure of the chlorophyll molecule Symptoms of deficiency are: Interveinal chlorosis occurring first in mature leaves Severe symptoms are completely yellow leaves or white Premature leaf abscission CHLORINE Found in plants as chloride ion (Cl–) Required in water-splitting reaction of photosynthesis through which oxygen is produced Cell division Deficient plants develop: wilting of young leaves followed by general leaf chlorosis and necrosis. leaves may exhibit reduced growth. Eventually, the leaves may take on a bronze-like color (“bronzing”) Roots may appear stunted and thickened near the root tips. MANGANESE Manganese ions (Mn2+) activate several enzymes in plant cells (decarboxylases and dehydrogenases involved in the tricarboxylic acid cycle) Photosynthetic reaction through which oxygen is produced from water Major symptom of manganese deficiency: Intervenous chlorosis associated with the development of small necrotic spots which may occur on younger or older leaves depending on plant species and growth rate Group 4: Mineral nutrients that are involved in redox reactions IRON Component of enzymes involved in the transfer of electrons (redox reactions), such as cytochromes where it is reversibly oxidized from Fe2+ to Fe3+ during electron transfer. Symptoms of iron deficiency: Intervenous chlorosis which appear initially on the younger leaves because iron cannot be readily mobilized from older leaves. Prolonged deficiency may cause chlorotic leaves, causing the whole leaf to turn white. ZINC Required for the activity of many enzymes as Zn2+ Chlorophyll biosynthesis Deficiency is characterized by: In some species (corn, sorghum, beans), the older leaves may become intervenously chlorotic and then develop white necrotic spots. Bronzing of leaves Reduction in internodal growth (Rosetting) in which the leaves form a circular cluster radiating at or close to the ground. The leaves small and distorted, with leaf margins having a puckered appearance. Symptoms result from loss of the capacity to produce sufficient auxin IAA COPPER Like iron, copper is associated with enzymes involved in redox reactions being reversibly oxidized from Cu+ to Cu2+ (Plastocyanin) Initial symptom is the production of dark green leaves, which may contain necrotic spots which appear first at the tips of the young leaves and then extend toward the leaf base along the margins. leaves may also be twisted or malformed Under extreme deficiency, leaves may abscise prematurely NICKEL Required by Ni-containing enzyme Urease Nickel-deficient plants accumulate urea in their leaves and, consequently, show leaf tip necrosis. Inhibited root growth Occur seldom because the amounts of nickel required are minuscule. MOLYBDENUM Components of several enzymes (nitrate reductase and nitrogenase) NR catalyzes the reduction of nitrate to nitrite during its assimilation by the plant cell; N converts nitrogen gas to ammonia in nitrogen- fixing microorganisms Deficiency: Silvery patches between veins and necrosis of the older leaves. Cauliflower or broccoli, the leaves may not become necrotic but may appear twisted and subsequently die Whiptail disease (also Boron) Flower formation may be prevented, or the flowers may abscise prematurely. May bring about N deficiency if the plant is depending on symbiotic N-fixation  Solution Culture Technique: Hydroponics Exposing the roots in nutrient solutions containing all the essential elements Simple and inexpensive Provides a controlled environment for observing the effect of a specific element Julius von Sachs developer of the solution culture technique in the early 1860s Plants could be grown up to maturity in culture solutions Dennis R. Hoagland Pioneer in the study of mineral nutrition Developed his own formulation of culture solution Modifications 1. Solution Culture technique – growing plants in suitable containers with their roots immersed in dilute acqueous solution of the mineral salts 2. Aeroponic technique – confining the root system in a humidity rich airtight container with the culture solution supplied as a spray or whipped into a fine mist by a driver attached to the motor shaft 3. Nutrient film technique – nutrient solution is pumped as a thin film down a shallow trough surrounding the plant roots 4. Sand culture technique – the use of solid growth medium such as white sand, perlite or vermiculite which affords the plant better root anchorage and aeration  Continuation of Previous Lecture: Plant Nutrition Role of Fertilizers In a natural ecosystem, minerals removed and absorbed by plants are replaced when the plants or animals that consumed plants die and decompose. Agricultural setting, the nutrient balance is disrupted since the plants biomass is harvested and taken elsewhere. Over time, soil fertility loses and its ability to produce crops abundantly diminishes. Nitrogen, Phosphorus and Potassium (NPK) are three elements that are most often limiting resources for plants as they are needed in high quantities. Common fertilizers and their compositions (grade). Adopted from US EPA, 2000 Note: In the Philippines, Urea grade is commonly 45-0-0 and Complete Fertilizer is 14-14-14.  Basic fertilizer Computation Four “Finds” Generally, there are three numbers that describe, in in Fertilizer Calculations Find the area order, the concentrations of N-P2O5 -K2O. For example, a fertilizer bag of diammonium Find the rate (per area) phosphate will have the numbers 18-46-0 on it, (Recommended Rate) This means it contains a minimum of 18 percent N, 46 percent P2O5, and no K2O by weight. Find the amount of nutrient (area * rate) Find the amount of fertilizer (nutrient/concentration)  Three Basic Types of Calculations 1. You have a given amount Converting Fertilizer to Nutrient of fertilizer and you need to calculate how much Amount of nutrient = Amount of fertilizer x Fertilizer Grade (%) nutrient is in it 2. You have a given amount of nutrient to apply and Converting Nutrient to Fertilizer you need to calculate Amount of fertilizer = Amount of nutrient /Fertilizer Grade (%) how much fertilizer to use 3. Computing the amount of fertilizer to be applied in a given area Amount of fertilizer = Recommended Rate (kg/ha)/Fertilizer Grade (%)  Examples Your father has a 50kg granular complete fertilizer with a label that reads 15-10-10. This means the grade is 15% N, 10% P2O5 and 10% K2O. How many kg P2O5 is contained in the bag? How many kg P is in the bag?  Single Element Fertilizer: What fertilizer and how much does he need to apply in his 10ha rice field if after soil analysis the suggested rate of application is 60-0-0 kg/ha? He needs Urea (45-0-0)  For Multiple Elements Fertilizer computations, please refer to this link: https://s3.wp.wsu.edu/uploads/sites/2076/2014/11/Veg-Crops-Lesson-X- Fertilizer-calculations.pdf  Transport in the Phloem Translocation (food transport) takes place in the SIEVE TUBE MEMBERS Sucrose – translocatable sugar in plants PHLOEM Movement in phloem is from a SOURCE to a SINK by BULK A source is a plant organ in which either photosynthesis or breakdown of starch to sugar is occurring A sink is an organ that consumes, or stores (converts sugars to starch) sugar Some sugar storing organs, e.g. tubers, rhizomes, corms, etc. can be either sources or sinks Pressure-Flow Hypothesis Mass Flow; Bulk Flow Mechanism Münch Theory High solute concentration at source lowers water potential and causes water to flow into the source at a rapid rate. At the sink, sugar concentration is low and water potential high, resulting in water flowing rapidly out of the sink. The building of pressure at source and reduction of pressure at sink causes water to flow from source to sink.  Phloem Loading (at the Source) starting point for long-distance nutrient transport. solute is actively concentrated in the phloem of source organs, generating hydrostatic pressure. generally takes place against a concentration gradient. an “endothermic pumping action.” carries molecules against their thermodynamic gradient into the phloem Phloem Loading Types Liesche & Patrick 2017  Active Apoplasmic Loading the sugars are actively loaded from apoplast to sieve tubes by an energy driven transport located in the plasma membrane of these cells. The mechanism of phloem loading in such case has been called as sucrose-H+ symport or cotransport mechanism. Protons (H+) are pumped out through the plasma membrane so that concentration of H+ becomes higher outside (in the apoplast) than inside the cell. Spontaneous tendency toward equilibrium causes protons to diffuse back into the cytoplasm through plasma membrane coupled with transport of sucrose from apoplast to cytoplasm through sucrose -H+ symporter located in the plasma membrane.  Phloem Unloading (at the Sink) Series of cell-to-cell transport steps transferring phloem-mobile constituents from phloem to sink tissues/organs to fuel their development or resource storage 1. Sieve tube unloading sugars (imported from the source) leave sieve elements of sink tissues actively. 2. Short distance transport The sugars are now transported to cells in sink by a short distance pathway: post-sieve element transport. 3. Storage and metabolism sugars are stored or metabolized in the cells of the sink.  Summary All the inorganic elements except carbon, hydrogen and oxygen are called mineral elements. Mineral elements are distributed in soil Mineral elements have structural, functional and electrochemical role in plants. Essential elements are indispensable to the life of plants. Sugars manufactured in the green regions of plants is carried in the form of solution in water for consumption or storage in older cells, developing flowers and fruits, growing apices through phloem tissues. Insert Running Title 83  References Alfonso-Alejar, A. M. and M. L. Dionisio-Sese. 1999. Fundamentals of Plant Physiology. Plant Physiology Society of the Philippines. Pasig City, Metro Manila. 166 pp. Berg LR. 1997. Introductory Botany: Plants, People and the Environment. Saunders College Publishing. USA. Hopkins, W.G. 1999. Introduction to Plant Physiology. Second edition. John Wiley and Sons, Inc. 511 pp. Hopkins WG, Huner NPA. 2009. Introduction to Plant Physiology 4th Edition. John Wiley and Sons, Inc. USA. Mauseth JD. 2009. Botany: An Introduction to Plant Biology 4th Edition. Jones and Barlett Publishers, Inc. Sudbury. Moore R, Clark WD, Stern RK. 1995. Botany. Wm. C. Brown Publishers. USA. Moore R, Clark WD, Vodopich DS. 2003. Botany 2nd edition. WCB McGraw Hill. USA. Nabors MW. 2004. Botany: An Introductory Approach. Pearson Education/ Benjamin Cummings Inc. USA Sinha, R. K. 2004. Modern Plant Physiology. Alpha Science International Ltd. 620 pp. Taiz L, Zeiger E. 2002. Plant Physiology 3rd Edition. Sinauer Associates, USA. Insert Running Title 84