Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 02 Nutrition
Document related concepts
no text concepts found
Transcript
Chapter 5 Acquired primarily through the roots 2 Inorganic ions Nutrient cycles begin with plant roots – mining minerals from the soil Soil mycorrhizza & N-fixers assist Research central to Ag and environmental protection Crop plants utilize < 50% applied fertilizers Leech into ground water (spoiling wells) Attached to soil particles (N availability) Contribute to air pollution 3 OTOH ….. phytoremediation 4 “intrinsic component in the structure or metabolism of a plant or whose absence causes severe abnormalities in plant growth, development, or reproduction” C. HOPKiNS CaFe. Mighty good! (Macro- VS Micro-nutrients) VS Function 5 6 1. Part of carbon compounds a) Assimilated via ReDox rxns 2. Important in energy storage or structural integrity a) Typically as phosphate, borate, & silicate 3. Remain in ionic form a) Enzyme cofactors & regulation osmotic potential 4. Involved in ReDox reactions 7 8 9 10 Nutrient deficient solutions Modified Hoagland – Complete Nutrition Macronutrients: K, NO3, Ca, NH4, PO4, MgSO4 Micronutrients: KCl, BO3, Mn, Zn, Cu, SO4, Mo, Fe Optional: Ni, Na, Si 11 12 13 14 15 Typically characteristic symptomology Occur simultaneously in different tissues Defficiencies/excesses can induce deficiencies/excesses in other nutrients Viral infections mimic nutrient deficiencies 16 Essential element mobile – old leaves first Essential element non-mobile – young leaves 17 18 19 From the Hopkins text …. Macronutrient – required in large amounts In excess of 10mmole/kg of dry weight Generally involved in structure of molecules Micronutrients – small amounts Less than 10 mmole/kg of dry weight Catalytic and regulatory roles like enzyme acrivators Beneficial – not universal or not detectable 20 Na, Si, Se, Co Na – essential for C4 plants Si – 1-2% of dry matter Zea mays Up to 16% (or more) of Equisetum Cell walls of grasses to help against lodging Co -- required for N-fixing bacteria Se -- essential or tolerable? Loco weeds! (up to 0.5%) Only grow in high Se environments 21 Macro-/micro- versus functional Same nutrient often fills multiple roles! Mg – component of chlorophyll; also enzyme cofactor in ionic form Ca – component of cell walls; but also second messenger 22 23 Critical concentrations – concentrations measured in the tissues below the level that gives maximum growth Nutrient limits growth below critical concentration Toxicity can be observed with micronutrients Sources and Uses Constituent of many macromolecules Slow stunted growth Chlorosis of the leaves Accumulation of anthocyanin pigments in stems/leaves Excess N 24 Absorbed in the form of NO3- and NH4+ Deficiency Symptoms Proteins, nucleic acids, some hormones, chlorophyll Stimulates growth of the shoot system Delays onset of flowering Sources and Uses Deficiency Symptoms Intense green leaves Malformed leaves with necrotic spots Accumulation of anthocyanin pigments Excess 25 Nucleic acid backbone; metabolism; membranes Soil pH major role in availability Organic phosphates converted to inorganic forms Most commonly limiting nutrient -- mycorrhiza Stimulates growth of roots Sources and Uses Activates enzymes; osmoregulation (stomates in particular) Deficiency Symptoms Marginal chlorosis followed by necrotic lesions Increased suceptibility to root-rot 26 Sources and Uses Proteins (disulfide bridges), coenzymes (esp. A) and vitamins Mustard oils in Brassicoids Deficiency Symptoms Not a common problem; appropriate forms produced by soil microorganisms General chlorosis including tissues around X/P 27 Sources and Uses Important in cell division (mitotic spindle), cell adhesion (middle lamella), & second messenger Deficiency Symptoms Appear in meristems Deformed and necrotic new leaves Poor root growth 28 Sources and Uses Deficiency Symptoms 29 Chlorophyll, reactions with ATP, and regulator of enzyme activity Chlorosis due to breakdown of chlorophyll between veins Sources and Uses Of all micronutrients, required in largest amounts Chlorophyll synthesis – but precise role is mystery! Deficiency Symptoms 30 Enzymes not Fe-dependent T&Z says chlorophyll-protein complexes Loss of chlorophyll – intervenous spaces (serious leaves turn white) Degeneration of chloroplast Multiple strategies for enhancing uptake Sources and Uses Cell division, elongation, and integrity of cell wall Least understood Deficiency Symptoms Structural abnormalities of cell walls Inhibition of both division and elongation in roots Cell division in shoot apex and young leaves inhibited Necrosis of the meristem Shortened internodes & enlarged stems 31 Sources and Uses Cofactor for oxidative enzymes Browning of apple and potato surfaces! Deficiency Symptoms 32 Stunted growth, distortion of young leaves, and loss of young leaves. Sources and Uses Activator for numerous enzymes Deficiency Symptoms Auxin metabolism Shortened internodes and smaller leaves Precise mechanism unclear! 33 Sources and Uses Enzyme cofactor Part of Oxygen-evolving complex Deficiency Symptoms Aggravated by low pH and high organic content “Gray speck” in cereal grains Chlorosis between veins Discoloration and deformities in legume seeds 34 Sources and Uses Key component of N metabolism Deficiency Symptoms In N-fixers can produce symptoms of N deficiency! Young leaves twisted and deformed Chlorosis and necrosis Highly species dependent 35 Legumes, Brassicoids, and maize Sources and Uses Deficiency Symptoms 36 Oxygen evolution and charge balance across membranes Reduced growth, wilting of leaf tips, chlorosis Sources and Uses Not clear Ubiquitous in plant tissue – amt in seed sufficient! Studies – multiple generations of Ni-deficient plants Deficiency Symptoms Low germination rates (< 12%) 37 increased Ni to 0.6 μM OR 1.0 μM -> 57% and 95% Seedling vigor, chlorosis, necrotic lesions Micronutrients excellent examples of dangers of excesses 38 Critical toxicity level – 10% reduction in dry matter Symptoms difficult to diagnose – excess of one nutrient causes deficiency in another Typically inhibit root growth 39 40
