Strategies for drought ii tolerators leaves transpire

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Strategies for drought ii. Tolerators Leaves transpire slowly Sunken stomata E.g. pines Cost: slower photosynthesis More efficient photosynthesis E.g. C4 --> reduces photorespiration E.g. CAM --> stomata open at night
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Water absorption Root hairs increase surface area Water depletion zone develops around root, esp. in clay soils
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Structure of the root system varies between species, depending on the amt. of soil moisture in their env’t Individual species show phenotypic plasticity wet soil --> shallow roots near surface (greater oxygen availability) dry soil --> deep roots
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3. Minerals Acquired from soil Macronutrients Needed in large quantities (conc. in dried plant tissues > 1 ‰) N, P, K, S, Ca, Mg, Cl Micronutrients Small quantities Mn, Zn, Cu, Fe, B, I, Se, Co, Mo Plant resources
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Resource depletion zones Develop around roots Limiting nutrient: NO 3 - PO 4 3 - Diffusion rate Fast slow Depletion zone? No Yes (~ 0.1 mm radius around root) Best root morphology Long, infrequent branching Short, frequent branching
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Nutrient uptake rates Reach plateau with increasing nutrient concentration
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Fig 6-24
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