Plant Mineral Nutrition and Biogeochemical Cycles | NRSC 200, Study notes of Earth Sciences

Download Plant Mineral Nutrition and Biogeochemical Cycles | NRSC 200 and more Study notes Earth Sciences in PDF only on Docsity! PLANT MINERAL NUTRITION AND BIOGEOCHEMICAL CYCLES What do plants need? (light, water, space and several nutrients) Review – law of conservation of matter, unlike energy, ecosystems are “closed” (depending on scale) for all matter or are they? So all minerals must be recycled at some level. Soil – plant – animals – decomposition (fungi, bacteria, invertebrates and vertebrates involved) – soil. In addition to environmental factors (temp and water), energy flow and the interactions among organisms ecosystems may be limited by nutrients and the rates they are cycled. Implications? Nutrient Limitations: Justice von Liebig: 1800s Organic chemical organization, developed a system of teaching based on laboratories, discovered N as a an essential plant element, law of the minimum (mid- 1800s, although first described in about 1828 by Carl Sprengel) – called the “father of fertilizer.” Also trademarked the “bouillon cube!” Hole in the barrel theory: This is now utilized in models that explain growth of organisms, populations and ecosystem productivity 1 Nutrient Availability: Environmental consequences Cost Energy Use Nutrient waste or loss: Plants don’t take up all the nutrients that we put on them – who cares? Chesapeake Bay, etc. Role of agriculture in this? Minerals are normally cycled through Biogeochemical cycles: They must be important to plant physiology, productivity and ecosystem functioning if they control ecosystem productivity. Also there are numerous interactions and ramifications of these cycles (nutrients, CO2 increases, interactions between organisms, etc.) as discussed in more detail in ecology and environmental science courses. Which elements are we talking about? C HOPKNS CaFé Mg Cl MoB CuMn(s) Zn Some are needed in larger quantities or have “critical” roles or are essential for survival and these are called Macronutrients. Others are needed in smaller quantities or have less serious consequences of deficiencies, Micronutrients. Others may be found in most or all plants or shown to be required in certain plants – e.g. Si, Ni, Na, Se, Al and F. 2 TABLE 5.2 Classification of plant mineral nutrients according to biochemical function (Part 1) Mineral nutrient — Functions Group1 Nutrients that are part of carbon compounds N Constituent of amino acids, amides, proteins, nucleic acids, nucleotides, coenzymes, hexoamines, etc. s Component of cysteine, cystine, methionine, and proteins. Constituent of lipoic acid, coenzyme A, thiamine pyrophosphate, glutathione, biotin, adenosine-5’-phosphosulfate, and 3-phosphoadenosine. Group 2 Nutrients that are important in energy storage or structural integrity Fy Component of sugar phosphates, nucleic acids, nucleotides, coenzymes, phospholipids, phytic acid, etc. Has a key role in reactions that involve ATP. Si Deposited as amorphous silica in cell walls. Contributes to cell wall mechanical properties, including rigidity and elasticity. B ‘Complexes with mannitol, mannan, polymannuronic acid, and other constituents of cell walls. Involved in cell elongation and nucleic acid metabolism. Source: After Evans and Sorger 1966 and Mengel and Kirkby 1987. PLANT PHYSIOLOGY, Fourth Edition, Table &2 (Port 1} © 2004 Snauor Associates, nc TABLE 5.2 Classification of plant mineral nutrients according to biochemical function (Part 2) Mineral nutrient — Functions Group 3 Nutrients that remain in ionic form K Required as a cofactor for more than 40 enzymes. Principal cation in establishing cell turgor and maintaining cell electroneutrality. Ca Constituent of the middle lamella of cell walls. Required as a cofactor by some enzymes involved in the hydrolysis of ATP and phospholipids. Acts as a second messenger in metabolic regulation. Mg Required by many enzymes involved in phosphate transfer. Constituent of the chlorophyll molecule. ll Required for the photosynthetic reactions involved in O, evolution. Mn Required for activity of some dehydrogenases, decarboxylases, kinases, oxidases, and peroxidases. Involved with other cation-activated enzymes and photosynthetic O, evolution. Na Involved with the regeneration of phosphoenolpyruvate in C, and CAM plants. Substitutes for potassium in some functions. Source: After Evans and Sorger 1966 and Mengel and Kirkby 1987. PLANT PHYSIOLOGY; Fourth Econ, Table 82 (Part 2) © 2006 Sina Aszcltes nc TABLE 5.2 Classification of plant mineral n TERM LT Mt One) Mineral nutrient —_ Functions Group 4 Nutrients that are involved in redox reactions Fe Constituent of cytochromes and nonheme iron proteins involved in photo- synthesis, N, fixation, and respiration. Zn Constituent of alcohol dehydrogenase, glutamic dehydrogenase, carbonic anhydrase, etc. Cu Component of ascorbic acid oxidase, tyrosinase, monoamine oxidase, uricase, cytochrome oxidase, phenolase, laccase, and plastocyanin. Ni Constituent of urease. In N,-fixing bacteria, constituent of hydrogenases. Mo Constituent of nitrogenase, nitrate reductase, and xanthine dehydrogenase. Source: After Evans and Sorger 1966 and Mengel and Kirkby 1987. ‘PLANT PHYSIOLOGY, Fout Eton, Tale 5.2 (Part 3) © 2005 Sas Assocs, no TABLE 5.4 MT CURA Re mE Ce male TC YN AVM CLAM Um Lie ( iC Coy eM M ima ira (= Mobile Immobile Nitrogen Calcium Potassium Sulfur Magnesium Tron Phosphorus Boron Chlorine Copper Sodium Zine Molybdenum Note: Elements are listed in the order of their abundance in the plant. PLANT PHYSIOLOGY, Fourth Eaton, Table 54 © 2008 Sina: Associates, Nitrogen: 2 to 6% in leaves, more like 1.5% in the whole plant. Used for amino acids – proteins – enzymes, nucleic acids, “energy” compounds, secondary compounds such as alkaloids. Probably the most significant in limiting terrestrial productivity – leads to specific environmental problems and issues. Symptoms in older leaves first – a mobile element. Stunting, chlorosis, yellowing, accumulation of carbohydrates and anthocyanins. Issues also associated with excess N – vegetative growth, cold- hardiness/dormancy, acid deposition, etc. Potassium: ~1 % DW osmotic regulation, enzyme activation of some key PS and RE enzymes Symptoms in older leaves first – mobile. Marginal chlorosis, mottles, curled or crinkled leaves, thin stems, short internodes, intervenal necrosis when severe, may increase fungal susceptibility of roots. Phosphorus: ~ 0.2% dry weight – small amount of the “Big 3”, but hugely important biologically – may limit productivity in aquatic ecosystems. Important for nucleic acids (sugar phosphates), ATP, etc. and as important metabolic (enzyme) regulators as Pi and as PO4 (phosphorylation). Mobile – older leaves first Symptoms: stunting, dark green leaves, anthocyanin production, necrosis. Also issues here with excess – ecosystem effects, Chesapeake Bay, etc. 7 Micronutrients – STEM fertilizers Cl: ~ 100 ppm Required for the water splitting reactions of PS-II (oxygen evolution). May be required for cell division in some species. Deficiency not a problem in the field – soluble and plentiful but seen as chlorosis, stunting, wilting, bronzing and necrosis in severe cases. B: ~ 20 ppm possibly important for cell elongation as part of cell carbohydrate complexes, nucleic acid synthesis and metabolism, hormone and membrane functioning. Not mobile – black necrosis of young leaves and terminal buds, lack of apical dominance results from this and also may be due to disruption of hormone functioning. Mn: ~50 ppm stabilizes and activates the water splitting (D1) proteins of PS-II, activation of key enzymes, decarboxylases and dehydrogenases of TCA cycle. Intervenal chlorosis and small nectotic spots – may be on young or older tissues 10 Zn: ~ 20 ppm enzyme activation, especially for chlorophyll synthesis, mobile – chlorosis and white spots of older leaves, reduced internode elongation and rosette formation perhaps due to reduction in auxin function, smaller sometimes puckered leaves Na: ~10 ppm most CAM and C4 plants require it to regenerate PEP, some C3 plants benefit from it, may enhance cell expansion and substitute for K as an osmoticam mobile, chlorosis and possible necrosis, lack of flowering, stunting or reduced PS in CAM and C4. Very rarely limiting. Cu: ~6 ppm enzymes in electron transport – PC in photosynthesis electron transport not very mobile – dark green leaves (compare to P) that may have necrotic spots, starts at the tips and moves toward the base, leaves may be twisted or misformed, may abscise in extreme cases Mo: 0.1 ppm (extremely low levels needed!) Key component of nitrogenase and nitrogen reductase enzymes Thus may appear like a N deficiency – intervenal chlorosis and necrosis of older (mobile) leaves, stunting, leaves may also be twisted – whiptail disease, flower formation retarded. 11 Ni: ~0.1 ppm may be required by some N fixing microbes, required by urease enzyme which breaks down urea so linked to N metabolism deficiency extremely rare due to amount required (but see Mo above) but may appear as accumulation of urea and leaf tip necrosis (mobile). Si: ~0.1 % larger amounts than some of the above (% not ppm) but only required (we think) for the scouring rushes (soap pad plants), Equisetaceae (tip - use it when you get on survivor!) may be in the cell wall as hydrated silica (SiO2 X H2O) where it gives some support by complexing with polyphenolics some other plants accumulate it and deficiency may weaken the plant, make it susceptible to lodging and lead to fungal damage. 12