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AP Biology Lecture #54 Plant Nutrition
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Experimentation 2005-2006 Testing pressure flow hypothesis using aphids to measure sap flow & sugar concentration along plant stem
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Maple sugaring 2005-2006
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Plant Nutrition
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Nutritional needs 2005-2006 Autotrophic does not mean autonomous plants need… sun as an energy source inorganic compounds as raw materials water (H 2 O) CO 2 minerals
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Macronutrients 2005-2006 Plants require these nutrients in relatively large amounts C, O, H, N, P, K, Ca, Mg, S
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For what & from where? 2005-2006 C synthesisCO 2 O synthesisCO 2 H synthesisH2OH2O N protein & nucleic acid synthesissoil & fertilizer P nucleic acids, ATP, phospholipidssoil & fertilizer K stomate control, water balancesoil & fertilizer Ca cell wall & membrane structure, regulationsoil Mg chlorophyllsoil S proteins, enzymessoil
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Local Long Island soil issues 2005-2006 Granite Acid soils bind up mineral ions pH by adding lime Quartzsilica based soils - low in P - can be acid
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Micronutrients 2005-2006 Plants require in very small amounts primarily cofactors
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Nutrient deficiencies 2005-2006 Lack of essential nutrients exhibit specific symptoms dependent on function of nutrient dependent on solubility of nutrient
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Magnesium deficiency 2005-2006 Symptoms chlorosis = yellowing of leaves what is magnesium’s function? Take 2 fertilizer pellets & call me in the morning
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Chlorophyll 2005-2006 Why does magnesium deficiency cause chlorosis? The chlorosis shows up in older leaves first, because plant moves Mg to newer leaves. Why?
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Water & mineral uptake 2005-2006 Water uptake plants cannot extract all water from soil, only free water osmosis Cation uptake cation uptake is aided by H + secretion by root cells (proton pump) active transport
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The role of soils 2005-2006 Plants are dependent on soil quality texture / structure relative amounts of various sizes of soil particles composition organic & inorganic chemical components fertility
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Importance of organic matter 2005-2006 Topsoil most important to plant growth rich in organic matter humus decomposing organic material breakdown of dead organisms, feces, fallen leaves & other organic refuse by bacteria & fungi improves soil texture reservoir of minerals organisms 1 tsp. of topsoil has ~5 billion bacteria living with fungi, algae, protists, insects, earthworms, nematodes So don ’ t rake your lawn or bag your leaves
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Soil health as a global issue 2005-2006 Not taking care of soil health has far-reaching, damaging consequences 1920’s Dust Bowl lack of soil conservation growing wheat raising cattle land exposed to wind erosion drought
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Soil health as a global issue 2005-2006 Soil conservation & sustainable agriculture maintaining healthy environment production of food supply economically viable farming industry contour plowingcrop rotation “A sustainable agriculture does not deplete soils or people.” – Wendell Berry cover crops
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Global issues 2005-2006 fertility erosion irrigation forestry destruction
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2005-2006
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Fertilizers 2005-2006 “Organic” fertilizers manure, compost, fishmeal “Chemical” fertilizers commercially manufactured N-P-K (ex. 15-10-5) 15% nitrogen 10% phosphorus 5% potassium
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Nitrogen uptake 2005-2006 Nitrates plants can only take up nitrate (NO 3 - ) Nitrogen cycle by bacteria trace path of nitrogen fixation! What will the plant use N for? root
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Soybean root nodules 2005-2006 N fixation by Rhizobium bacteria symbiotic relationship with bean family (legumes)
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Increasing soil fertility 2005-2006 Cover crops growing a field of plants just to plow them under usually a legume crop taking care of soil’s health puts nitrogen back in soil erosion control, too Plow it under? Why would you that? A man … outstanding in his field
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Some plant oddities… 2005-2006
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Parasitic plants 2005-2006 tap into host plant vascular system Indian pipe Mistletoe
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Plants of peat bogs 2005-2006 High acid environment most minerals & nutrients bound up & are not available to plants must find alternative sources of nutrients
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Carnivorous plants 2005-2006 Are they really carnivores? Pitcher plantVenus fly trap Sundew
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2005-2006 Pitcher plant
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Uses of peat 2005-2006
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Any Questions?? 2005-2006
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