Botany: Nutrition and Hormones

nutrients that plants get from da air

carbon (carbon dioxide) and oxygen (oxygen gas)

nutrients that plants get from the soil

• macronutrients: making up more than 0.5% dry weight

• micronutrients: nutrients in smaller quantities making up less than 0.5% of dry weight

explain humus

• humus is non-living organic matter, leftovers of living things

• breaks down over time by action of fungi and bacteria, ultimately releasing their minerals; often used quickly and must be replaced over time, as in the case of fertilizer or manure

how do most plants absorb nutrients

they are absorbed in the form of ions

ion and PH relationship

availability of ions is impacted by pH, so pH of soil is important to consider

what charge do clay and humus have

negative charge, so they hold onto POSITIVE ions

what charge does sand have

low cation exchange capacity, so low nutrient holding ability

Macronutrient: Carbon

comes from carbon dioxide in the air

Macronutrient: Oxygen

from carbon dioxide and oxygen gas in the air, from ions of various sorts

Macronutrient: Hydrogen

from water and from ions of various sorts

Macronutrient: Nitrogen, and how it is transported

• used in amino acids, proteins, enzymes, pigments, DNA, ATP

• transported in the phloem, thus if there’s a lack of N, there is chlorosis of older leaves as the plant breaks down older parts and sends it to younger leaves

• vegetative growth is limited by N (plants use nitrate, nitrogen and ammonium

• nitrogen-fixing bacteria, especially with legumes, convert N2 to NO3-

Macronutrient: Potassium

compatible solute, can occur at high concentrations without much negative effect; can be moved around in cytoplasm, organelles, vacuoles, important activator in proteins

Macronutrient: Calcium

activator of cell response, sequestered for active transport; high concentration of meristems; thus Ca deficiencies result in blosson-end rots and tip withering

Macronutrients: Mageniusm

important in chlorophylls, activator of enzymes, including DNA polymerase

Macronutrient: Phosphorus

Used in RNA, DNA, ATP, phospholipids; much of it is insoluble in the soil; mycorrhizae help in the uptake; a lack of P results in dark-green or blue-green leaves

Macronutrient: Sulfur

a part of the amino acids cysteine and methionine and in respiration; immobile

Micronutrient: Silicon

accumulated in some tissues for strength and resistance to pests

Micronutrient: Chlorine

needed in one step of photosynthesis for the splitting of water, also a counter-ion for K+ in stomata function

Micronutrient: Iron

synthesis of pigments, needed for conversion of nitrogen to useable forms, oxidation-reduction reactions in respiration

Micronutrient: Manganese

required with Cl in production of oxygen in photosynthesis, also major enzyme activator in the Krebs Cycle

Micronutrient: Sodium

required by C4 and CAM plants for regeneration of PEP

Micronutrient: Zinc

component of numerous enzymes

Micronutrient: Molybdenum

required for nitrogen metabolism, deficient in acidic soils

What do the 3 numbers on fertilizers equal

nitrogen, phosphate (P2O5), and potassium (potash)

Internal factors that affect plant growth, development, and differntiation

• genetic direction

• chemical signaling

External factors that affect plant growth and development

• light

• temperature

• daylength

• gravity

Hormones as chemical signals in plants

• are synthesized in one part of the body

• are transported to another part of the body

• induce a chemical response to control a specific physiological event

• often a at very low concentrations

Auxins hormone facts

• cause cell elongation and root initiation

• the mechanism of action is the pumping of H+ ions in the cellulose wall matrix, loosening the cell walls for growth

• found in young leaves and shoot apical meristem

What is the most common auxin hormone

indole-3-acetic acid

How may an auxin hormone harm a plant

auxins may also be used to killed plants, especially dicots, including one of the most widely used herbicided, 2,4-D

Cytokinins hormone facts

• mainly produced in the roots and transported in xylem to shoots, but also common in seeds

• originally found in coconut milk

• used in plant growth media/tissue culture

• promotes cell division

Most common cytokinnins

Zeatin, found in corn and maize

Ethylne hormone facts

• fruit ripening (especially in fruits like apples and bananas),

• often inhibits cell expansion

Climacteric plant definition

refers to fruits that show a large increase of respiration; non-climacteric fruits gradually ripen

Abscisic Acid Hormone facts

• promotes dormancy, prevents seed germination, and induces stomatal closing

• not involved in abscission, but found in high concentrations in recently abscised leaves

• without this hormone, seeds would germinate at any point and time

Gibberellins hormone facts

• first discovered as a substance in fungus that caused rice to grow long and spindly

• more than 100 kinds have been discovered, but GA3 is the most common

• stimulates cell division and cell elongation, cause bolting in rosette plants

• many of the cultivars in the Green Revolution involve less gibberellin or less response

hooray

yippee