Chapter 37 Plant Nutrition Nutritional needs Autotrophic does

Chapter 37. Plant Nutrition

Nutritional needs § Autotrophic does not mean autonomous u plants need… § sun as an energy source § inorganic compounds as raw materials w water (H 2 O) w CO 2 w minerals

Macronutrients § Plants require these nutrients in relatively large amounts u C, O, H, N, P, K, Ca, Mg, S For what From where C O H Photosynthesis CO 2 photosynthesis H 2 O N protein & nucleic acid synthesis soil & fertilizer P nucleic acids, ATP, phospholipids soil & fertilizer K stomate control, water balance soil & fertilizer Ca cell wall & membrane structure, regulation soil Mg S chlorophyll soil proteins, enzymes soil

Micronutrients § Plants require in very small amounts u primarily cofactors

Nutrient deficiencies § Lack of essential nutrients u exhibit specific symptoms § dependent on function of nutrient § dependent on solubility of nutrient

Magnesium deficiency § Symptoms chlorosis = yellowing of leaves u what is magnesium’s function? u

Chlorophyll Why does magnesium deficiency cause chlorosis? The chlorosis shows up in older leaves first, because plant moves Mg to newer leaves. Why?

Water & mineral uptake § Water uptake u u plants cannot extract all water from soil, only free water osmosis § Cation uptake u u cation uptake is aided by H+ secretion by root cells (proton pump) active transport

The role of soils § Plants are dependent on soil quality u texture / structure § relative amounts of various sizes of soil particles u composition § organic & inorganic chemical components § fertility

Importance of organic matter § Topsoil most important to plant growth u rich in organic matter u § humus w decomposing organic material w reservoir of minerals u organisms § 1 tsp. of topsoil has ~5 billion bacteria living with fungi, algae, protists, insects, earthworms, nematodes

Soil health as a global issue Not taking care of soil health has far-reaching, damaging consequences 1920’s Dust Bowl u lack of soil conservation u § growing wheat § raising cattle § land exposed to wind erosion § drought

Soil health as a global issue § Soil conservation & sustainable agriculture u u u maintaining healthy environment production of food supply economically viable farming industry contour plowing cover crops crop rotation

Fertilizers § “Organic” fertilizers u manure, compost, fishmeal § “Chemical” fertilizers commercially manufactured u N-P-K (ex. 15 -10 -5) u § 15% nitrogen § 10% phosphorus § 5% potassium

Increasing soil fertility § Cover crops u growing a field of plants just to plow them under § usually a legume crop § taking care of soil’s health w puts nitrogen back in soil erosion control, too

Nitrogen uptake § Nitrates plants can only take up nitrate (NO 3 -) § Nitrogen cycle by bacteria u trace path of nitrogen fixation! u root What will the plant use N for?

Soybean root nodules § N fixation by Rhizobium bacteria u symbiotic relationship with bean family (legumes)

Parasitic plants § tap into host plant vascular system Indian pipe Mistletoe

Carnivorous plants Sundew Venus fly trap Pitcher plant Are they really carnivores?

Pitcher plant