Soil and Plant Nutrition - Fundametnals of Biology - Lecture Notes, Study notes for Biology. Avinashilingam University


Description: These are the lecture notes of Fundametnals of Biology. Key important points are: Soil and Plant Nutrition, Macronutrients and Micronutrients, Symptoms of Mineral Deficiency, Genetic Modification, Resistance to Aluminum Toxicity, Flood Tolerance, Soil Bacteria
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1Chapter 37
Soil and Plant Nutrition
3Concept 37.2: Plants require essential elements to complete their life cycle
Plants derive most of their organic mass from the CO2of air, but they also depend on
soil nutrients such as water and minerals
4Macronutrients and Micronutrients
More than 50 chemical elements have been identified among the inorganic substances
in plants, but not all of these are essential to plants
A chemical element is considered an essential element if it is required for a plant to
complete its life cycle
Researchers use hydroponic culture to determine which chemical elements are
Nine of the essential elements are called macronutrients because plants require them
in relatively large amounts
The macronutrients are carbon, oxygen, hydrogen, nitrogen, phosphorus, sulfur,
potassium, calcium, and magnesium
The remaining eight are called micronutrients because plants need them in very small
The micronutrients are chlorine, iron, manganese, boron, zinc, copper, nickel, and
9Symptoms of Mineral Deficiency
Symptoms of mineral deficiency depend on the nutrient’s function and mobility within
the plant
Deficiency of a mobile nutrient usually affects older organs more than young ones
Deficiency of a less mobile nutrient usually affects younger organs more than older
The most common deficiencies are those of nitrogen, potassium, and phosphorus
11 Improving Plant Nutrition by Genetic Modification: Some Examples
Genetic engineering can improve plant nutrition and fertilizer usage
12 Resistance to Aluminum Toxicity
Aluminum in acidic soils damages roots and greatly reduces crop yields
The introduction of bacterial genes into plant genomes can cause plants to secrete
acids that bind to and tie up aluminum
Chapter 37 - Soil and Plant Nutrition
13 Flood Tolerance
Waterlogged soils deprive roots of oxygen and cause buildup of ethanol and toxins
The gene Submergence 1A-1 is responsible for submergence tolerance in flood-
resistant rice
14 Smart Plants
“Smart” plants inform the grower of a nutrient deficiency before damage has occurred
A blue tinge indicates when these plants need phosphate-containing fertilizer
16 Concept 37.3: Plant nutrition often involves relationships with other organisms
Plants and soil microbes have a mutualistic relationship
Dead plants provide energy needed by soil-dwelling microorganisms
Secretions from living roots support a wide variety of microbes in the near-root
17 Soil Bacteria and Plant Nutrition
The layer of soil bound to the plant’s roots is the rhizosphere
The rhizosphere has high microbial activity because of sugars, amino acids, and
organic acids secreted by roots
18 Rhizobacteria
Free-living rhizobacteria thrive in the rhizosphere, and some can enter roots
Rhizobacteria can play several roles
Produce hormones that stimulate plant growth
Produce antibiotics that protect roots from disease
Absorb toxic metals or make nutrients more available to roots
Inoculation of seeds with rhizobacteria can increase crop yields
20 Bacteria in the Nitrogen Cycle
Nitrogen can be an important limiting nutrient for plant growth
The nitrogen cycle transforms nitrogen and nitrogen-containing compounds
Most soil nitrogen comes from actions of soil bacteria
Plants absorb nitrogen as either NO3or NH4+
Bacteria break down organic compounds or use N2to produce NH3, which is converted
to NH4+
Nitrification is carried out by bacteria that convert NH3 into NO3
23 Nitrogen-Fixing Bacteria: A Closer Look
N2is abundant in the atmosphere, but unavailable to plants
Nitrogen fixation is the conversion of nitrogen from N2to NH3
Symbiotic relationships with nitrogen-fixing bacteria provide some plant species with a
Chapter 37 - Soil and Plant Nutrition
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khattak - Virtual University of Pakistan

got a great help in learning about macronutrients

23/04/13 12:54
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