BIOL 3427 1st Edition Lecture 15Outline of Current Lecture II. ProkaryotesIII. VirusesIV. FungiV. Symbiotic relationshipsCurrent LectureI. Plant Nutritiona. Relatively simple compared to animals b. DefinitionII. Essential elementsa. 17 essential elementsb. Element is essential if:i. Micronutrients( trace elements)1. Concentrations <100 mg/kg dry matterii. Macronutrients1. Concentrations>1000 mg/kg dry matteriii. Requirements differ among plant groups and speciesIII. Functions of Essential Elementsa. Many rolesi. Structural, enzymatic, regulatory, ionicb. Nutrient deficiency symptomsi. Most associated with shootii. Stunted growthiii. Necrosis1. Localized tissue deathiv. Chlorosis1. Loss or reduced chlorophyllyellowingv. Phloem-mobile elements1. Mg, P, K, N move readily through phloem2. Symptoms more pronounced in older leavesIV. The soila. Soils provide plant with:i. Supportii. Inorganic nutrientsiii. WaterThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.iv. Suitable gaseous environment for roots (roots need oxygen for respiration)b. Rock weatheringi. Heating and cooling causes fragmentation1. Produces inorganic soil componentsii. Weathered rock colonized by pioneer organismsiii. Decay adds organic soil componentsiv. Eventually, plant roots hold soil in placec. Soil Horizonsi. A horizon (topsoil)1. Upper region: has the most organic materiala. Humus: dark mixture of decomposed organic matterb. Living material: plant roots, decomposers (bacteria, fungi)ii. B Horizon (subsoil)1. Region of deposition: Fe Oxide, clay, some organic matter leach downward via wateriii. C Horizon (soil base)1. Weathered rocks from which the soil is formedd. Soil matter (inorganic portion)i. Sand (course to fine); largest particle sizeii. Silt (intermediate)iii. Clay: smalled (hold water)e. Pore spacei. Air and water surrounding soil particlesii. Approximately 50% of soil volume (good drainage-sand)f. Water potentiali. Indication of amount of water held in soilii. Also described as a plant`s water uptake abilityiii. Below minimum threshold, plant will wilt (not enough water)g. Soils retain cation (+), lose anion (-)i. Negative charged clay/humus surface binds cations (+)ii. Can be retained for plant growth by exchange with H+h. Biochemical cyclesi. Nutrient cycles inudure organisms and their physical environmenti. May be be global or localizedi. Global (gaseous): C, O, S, Nii. Localized: P, Ca, K, micronutrientsj. Where is most Nitrogen on earth?i. In atmosphere 78%k. In what form?i. Nitrogen gas not usable by most organismsii. Nitrogen needed as ammonium or nitrate in soilsl. Three main processesi. Ammonificationii. Nitrificationiii. Assimilationm. Ammonification (Nitrogen mineralizationi. Dead organic matter first decomposed (poop, soil bac, fungi, work on decomposing dead stuff)ii. By saprotrophic bac, some fungiiii. Excess Nitrogen released on ammonium ions (NH4+)iv. Plants can take up ammoniumn. Nitrification (Oxidation of ammonium)i. Chemosynthetic autotroph Nitrosomonas1. Oxidize ammonium to nitrate ions (NO2-)ii. Another bacterium Nitrobacter1. Oxidizes nitrite to nitrate (NO3-)iii. Plants take up nitrateo. Assimilationi. Incorporation of nitrates and ammonium into organic compounds1. Nitrate reduced to ammonium inside a cell first2. Ammonium used to form amino acidsii. Plants form root nodulesp. Other nitrogen fixing bacteria free livingi. Some aerobic, others anaerobicV. Nitrogen cyclea. Nitrogen fixationi. Nitrogen gas reduced to NH4+ii. Only attain bacteria1. Rhizobium and bradyrhizobium symbiotic with legumes (beans, soybean)a. Mutualistic relationship2. Frankia with other plant