all affect transpiration: leaf area (smaller leaf area decreases transpiration), leaf orientation (vertically orientated leaves decrease transpiration), leaf surface (waxy, hairy or shiny leaf surfaces decrease transpiration), and stomata (when stomata are closed, transpiration decreases)
An environmentally friendly form of landscaping that uses a variety of indigenous and drought-tolerant plants, shrubs, and ground cover.
affect transpiration: high humidity decreases transpiration, low temperature decreases transpiration, high light intensity increases temperature/transpiration, wind increases, dry soil decreases transpiration.
techniques used to decrease transpiration
: mist/spray foliage, decrease light intensity, harden-off seedlings (decrease watering, temp, fertilizer), antitranspirants (chemicals that close stomata)
functions of water
:is a solvent (dissolves solutes), reagent (is used in biochemical reactions), translocation medium (water translocates solutes in xylem and phloem), temperature relations (stabilizes plants/environment, evaporative cooling, releases heat when freezes, constant temp during phase change), turgor pressure and growth
amount of water in air; absolute - g/m3, specific - g/kg, relative - % amount, vapor pressure - 1-55 mm Hg
uptake of water by roots
movement of water through plants, mainly through xylem
loss of water vapor from leaves and other above ground plant parts, mainly occurs through the stomata
loss of liquid water from leaves, occurs through hydathodes (similar to stomata, but they do not close)
site of water absorption; most absorption, mainly through root hairs because - they are numerous, large surface area, and they are rapidly/constantly produced
site of water absorption; little absorption due to - suberization of endodermis, and due to the periderm formation (bark)
cohesion theory of translocation in the xylem (holy sheeeet)
inside the xylem; 1) transpiration occurs and is the driving force, 2) causes negative pressure in leaves, 3) column of water is pulled up in the xylem and translocated due to: H-bonding, small size of xylem pores, and the negative charges on xylem walls
functions of transpiration
1) is the driving force for translocation: transpiration causes a negative pressure in leaves, which "pulls" the water up the xylem. 2) evaporative cooling of leaves: 540 cal of heat energy is dissipated for every gram of water that evaporates from leaves, which is a major contributor to the cooling of leaves. (transpiration is usually much greater than is needed to satisfy these two functions. Thus, many horticultural practices attempt to minimize excessive transpiration)
outdoor method of irrigation; flood, basin, and furrow. Advantages: good wetting, frost protection, can irrigate sections/rows. Disadvantages: need level land, distribution, uses lots of water, wasteful
method of irrigation; use for container plants, turf, fruits/vegetables. Advantages: irrigates sections, automated, evaporative cooling, frost protection. Disadvantages: high cost, wind disrupts, nozzles clog
outdoor method of irrigation; use for fruit and row crops. Advantages: most water efficient, less plant stress, low pressure equip. Disadvantages: high cost and the emitters can clog
chapin tube (or Spaghetti tube)
greenhouse method of irrigation; use for container plants. Advantages: keeps foliage dry and can be automated. Disadvantages: must use fine medium, gets tangled, and high costs.
greenhouse method of irrigation; use for container plants. Advantages: constant moisture, keeps foliage dry, can be automated. Disadvantages: needs fine medium, small pots, too wet for some, algae growth on mat.
subirrigation (ebb and flow)
greenhouse method of irrigation; use for container plants. Advantages: keeps foliage dry, can be automated and is highly efficient. Disadvantages: high cost, and disease may spread.
greenhouse method of irrigation; use on bench crops. Advantages: can be automated. Disadvantages: moderate cost.
the substrate in which plants grow. Usually applied to manufactured or synthetic soils, ie "potting soils", or highly amended soils, ex. landscape beds. 'Soil' is the outer weathered layer of the earth's crust. Need pores
functions of growing medium
1) support and anchorage, 2) supplies mineral nutrients 3), supplies water, 4) allows gas exchange
: A Horizon/topsoil - contains the roots, highly weathered, organic life abundant. B Horizon/subsoil - nonfertile, less weathered, less life. C Horizon/parent material - little weathered, little life. D Horizon/bedrock - rock base
type of soil; contain 20% or more organic matter. Includes: peat soil - contains greater than 65% organic matter, and muck soil - contains 20-65% organic matter.
mineral soil (field soil)
type of soil; contains less than 20% organic matter. Has 4 major components: air - 25% of volume; in larger pores. Water - 25% of volume; in smaller pores. Mineral particles - 44-49% of volume. And organic matter - typically about 1% in nature.
properties: 1) physical - simple, relatively unweathered, physically broken down parent material. 2) chemical - relatively inert, has little effect on soil chemistry/pH, poor nutrient holding capacity and fertility. 3) pore space - less total space, more large pores and fewer small holes, thus causes increased aeration and drainage but decreased water holding capacity.
intermediate chemical and physical properties between sand and clay
properties: 1) physical - structurally complex: colloidal, viscous when wet and hard when dry, composed of micelles, very large internal and external surface area, very small internal and external pores. 2) chemical - complex, negatively charged: very high cation exchange capacity and nutrient holding, capacity allows for flocculation (Ca) and de-flocculation (Na). 3) pore space - greater total pore space, more small pores and fewer large pores, thus causes decreased aeration and drainage but increased water holding capacity and fertility.
typical agricultural soil
an agriculturally productive soil is a balanced mixture of sand, silt, and clay. For example, a typical loam soil is composed of 40% sand, 40% silt, and 20% clay. This yields a balance between aeration vs. drainage vs. water holding capacity vs. fertility.
cation exchange capacity (CEC)
milliequivalents per 100 grams dry soil (meq/100g); Sand: 2-4, Silt: 4-10, Clay: 10-100, and organic matter: 150-300. 'Percent base saturation' is the % total CEC occupied by basic nutrients, such as Ca, Mg, K, and Na.
a measure of the acidity of a solution. Below 7 is acidic, 7 is neutral, and above 7 is basic. This figure is seldom high or low enough to directly affect plants. Its major effect is on the solubility of nutrients in the soil, ie nutrient availability in the soil for plants to use
low pH nutrients (micronutrients)
elemental nutrients available at pH below 5.5: Iron (Fe), Zinc (Zn), Copper (Cu), Manganese (Mn), and Boron (B)
intermediate pH nutrients
elemental nutrients available at pH 6-7: Phosphorous (P)
high pH nutrients (macronutrients)
elemental nutrients available at pH above 6.5: Nitrogen (N), Potassium (K), Magnesium (Mg), Calcium (Ca), Sulfur (S), and Molybdenum (Mo).
chemicals that increase pH
: calcitic lime, dolomite, hydrated lime, burned lime, and basic fertilizers (nitrate)
chemicals that decrease pH
: elemental sulfur, aluminum sulfate, iron sulfate, acidic fertilizers (urea, ammonia, ammonium)
soils with acid pH; in regions of high rainfall
basic soils (alkaline soils)
soils with basic pH; in arid regions
how to improve saline/sodic soils
a) leach - application of large volumes of water to remove excess soluble salts. b) add elemental sulfur - acidifies the soil. c) add gypsum - the Ca promotes good soil structure, drainage and Na leaching.
form of growing media; top three: peat moss, composted bark, and coir. Others include: sawdust, cedar chips, rice hulls, bagasse, cotton gin trash, and sludge.
form of growing media; top four: sand, vermiculite, perlite, styrofoam. Others include: calcined clay, rice hull ash, and rock wool.
typical growing medium
should include a mix of organic and inorganic amendments; 50-75% organic amendments and 25-50% inorganic amendments
chemically combined water
form of soil moisture; occurs as a water shell around compounds and particles in soil, plants cannot utilize.
form of soil moisture; water absorbed onto soil particles, held at less than -31 bars of tension, plants cannot utilize.
form of soil moisture; water held by capillary attraction in the capillary pores in soils, held at -1/3 to -31 bars. Plants can extract water in the larger capillary pores down to approximately -15 bars.
water in large pores immediately after water or a rain, which drains from the soil (within 24 hr) by the force of gravity; held at greater than -1/3 bars (0 to -1/3 bars); plants can utilize when present.
the amount of water a soil can hold against the force of gravity, the water at this level is held at -1/3 bars.
the loss of plant turgidity due to excessive water loss
when a plant wilts, but recovers when placed in a saturated atmosphere (100% RH), ex. overnight.
when a plant wilts, but cannot recover when placed in a saturated atmosphere (100% RH)
any material applied to the surface of the soil or growing medium. Almost always beneficial to use, and their use is highly recommended. In nature, the soil under plants is covered by a natural mulch of composting litter. Can be organic (bark, leaves, sawdust) and inorganic (plastic, gravel)
benefits and uses of mulch
1) stabilizes soil temp, 2) conserves water, 3) better water infiltration, 4) controls erosion, 5) may add nutrients, 6) decreases weed growth, 7) aesthetic appearance
an element required by plants for normal growth, development and completion of its life cycle, and which cannot be substituted for by other chemical compounds
elements supplied by air and water
elements required by plants; these comprise the bulk of the plant - C, H, and O
elements required by plants; required at 1% to 10% of the dry weight of plants - N, P, K, S, Ca, and Mg. (the elements available at high pH)
elements required by plants; required at 1 to 300 ppm of the dry weight of plants - Fe, Zn, Cu, Mo, B, Mn, Cl, and Ni. (the elements available at low pH)
movement direction in plants; means towards the apex; transport up in the xylem.
movement direction in plants; means towards the base; transport down in the phloem.
classification of nutrient mobility; moves both up and down the plant by both acropetal and basipetal transport (in both xylem and phloem). (Deficiency appears on older leaves first). Elements: N, P, K, Mg, S (macronutrients)
classification of nutrient mobility; moves up the plant by only acropetal (in the xylem) transport. (Deficiency appears on new leaves first). Elements: Ca, Fe, Zn, Mo, B, Cu, Mn (micronutrients)
sequence of 3 numbers on the fertilizer label that gives the percent composition of N - P - K in a fertilizer; required by law to be on the label of every fertilizer sold.
the relative proportion of N to P to K in a fertilizer; 8-8-8 would be 1-1-1. Vegetative growth is favored by a fertilizer using a high N, low P and K. And flowering/root growth is favored by using a low N, high P and K in the ratio.
basic soil (or alkaline): has greater than 2000 ppm total soluble salts
: low to moderate total salts, but 15% or more of CEC is occupied by Na (sodium).
basic soil (or alkaline); greater than 2000 ppm total soluble salts and 15% or more of CEC occupied by Na.
yellowing of leaves; caused from a deficiency in certain types of micro and macronutrients
browning of leaves, dying of leaf; caused from a deficiency in certain types of micro and macronutrients
macronutrient; it's characteristic deficiency symptom occurs on OLDER leaves, and is overall chlorosis. Fertilizer sources include: ammonium nitrate (NH4), sulfate, phosphate, K/Na/Ca nitrate, and urea
macronutrient; it's characteristic deficiency symptom occurs on OLDER leaves, with deep green, purple coloration on the petioles. Fertilizer sources include: superphosphate, ammonium nitrate (NH4), phosphate, and phosphoric acid.
macronutrient; it's characteristic deficiency symptom occurs on OLDER leaves, interveinal chlorosis with marginal and tip necrosis. Fertilizer sources include: K nitrate, chloride, phosphate or sulfate.
macronutrient; it's characteristic deficiency symptom occurs on OLDER leaves, interveinal chlorosis and bronze coloration. Fertilizer sources include: dolomite, Ca/Mg carbonate, Mg sulfate, and epsom salt
macronutrient; it's characteristic deficiency symptom occurs on the dying stem tips, and also on small leaves. Fertilizer sources include: limes, Ca sulfate/nitrate and carbonate, and superphosphate
macronutrient; it's characteristic deficiency symptom occurs on all leaves with overall chlorosis; YOUNG leaves first then progressing to OLDER leaves. Fertilizer sources include: sulfate carriers, elemental S, and superphosphate.
micronutrient; it's characteristic deficiency symptom occurs on YOUNG leaves, with severe interveinal chlorosis. Fertilizer sources include: Fe chelate and sulfate, and some pesticides.
micronutrient; it's characteristic deficiency symptom occurs on YOUNG growth, with rosetted growth (clustered) and small leaves. Also referred to as 'witch's broom'. Fertilizer sources include: Zn chelate and sulfate, and some pesticides.
micronutrient; it's characteristic deficiency symptom occurs on YOUNG leaves, with interveinal chlorosis with necrosis when severe. Fertilizer sources include: Mn chelate and sulfate, and some pesticides.
micronutrient; it's characteristic deficiency symptom occurs on stunted and dying stem tips, small leaves, with multiple buds formed. Fertilizer source include: Cu chelate and sulfate, and some pesticides.
micronutrient; it's characteristic deficiency symptom occurs on stem tips, short, thick internodes, thick, brittle leaves with necrosis. Fertilizer sources include: borax and boric acid.
micronutrient; it's characteristic deficiency symptom occurs on YOUNG leaves with overall chlorosis. Fertilizer sources include: Na or ammonium nitrate (NH4) molybdate.
chlorosis or necrosis occurring between the veins on a leaf
mineralization (or ammonification)
the conversion of organic nitrogen to inorganic nitrogen (in the form NH4). The speed of conversion depends on the C:N ratio
a two step process converting ammonium to nitrite, then nitrite to nitrate. The soil bacterium 'Nitrosomonas' converts ammonium to nitrite. And the soil bacterium 'Nitrobacter' converts nitrite to nitrate. This occurs very quickly so little ammonium (toxic) and virtually no nitrite (highly toxic) accumulates in the soil.
the conversion of nitrate in the soil to gaseous nitrogen that escapes into the atmosphere.
the conversion of gaseous nitrogen to ammonia (which plants can use). Only nitrogen fixing microorganisms can cause this; some form symbiotic relationships with plants.
proportion of carbon to nitrogen present in organic matter. A HIGH ratio depletes soil nitrogen, includes: wood, sawdust, and uncomposted bark. A LOW ratio adds nitrogen, includes: manure, bone meal, fish emulsion, and organic fertilizers.
shrinkage of individual cells due to loss of turgor pressure that causes a cell to become flaccid
non-functional (dead) xylem
functional (but dead) xylem