Tropical: Warm year round, only "season" may be wet/dry, Hawaii
Monsoon: Seasonal rain, no monsoon climate in US but sometimes have monsoon seasons
mild wet winter
two growing seasons
Moist soils and longer days
spring as days lengthen
fall after the first rains
For majority of plants in temperate zones, spring is when the majority of yearly growth takes place
yearly growth flush includes:
-Leafing out of trees
-Emerging and blooming of bulbs
-Blooming and fruit setting in fruit trees
-New shoot growth in shrubs and trees
Summer is a period of maturing in plants
some plants have their flowering period (Tomatoes and corn)
others, which flower in the spring enlarge/ripen fruits (deciduous fruit trees, apples)
New, tender spring leaves toughen
Many plants accumulate energy in the summer to enable them to live through the winter
In temperate climates Fall is a transitional season for plants that live many years and the end of life for those living one season
These surviving the winter enter dormancy to ensure their winter survival:
-triggered by short days, cooler weather, or both
-stop growth, drop leaves, decrease water content in the sap
Plants that live one year must have produced seed capable of sprouting in spring
Time of waiting
-when temperatures are below freezing, water is solid and cannot travel readily throughout the roots and stems.
Lack of water and leaves drastically slows biochemical processes in the plant
Elements combining to make up a climate:
the geographic range over which a plant will grow
the lowest temp a plant can stand
for many plant 28 degrees F is the minimum because at this temp the liquid contents of the plant cells freeze and expand, killing the plant
In many plants the woody stem or root system is frost-hardy but not the flowers and leaves
occurs when the air is cool and calm and skies are clear
warmth from the sun accumulated by the soil and plants during the day is lost at night as heat radiating upward
second type of frost is caused by a cold airy mass moving into an area, this is usually a more severe frost
sprinkler irrigation of plants is used to prevent frost
Rain, snow, hail, and sleet
lack of rainfall is limiting factor to plant growth
water stress can be a major growth limiting factor
Coastal fog can supplement lack of rainfall
Excessive rain or rain occurring out of season can be as detrimental to plants
Frequent rains spread plant diseases by splashing microorganisms from one leaf to the next
Snow cover plan an important role in plant survival in areas with cold winters
Precipitation- Snow cover
Snow cover plays an important role in plant survival in areas with cold winters
insulates low-growing plants form cold air
protects stems form freeze drying
Percipitation-sleet and hail
tear leaves and bruise or knock off fruits
Freezing rain can often cause branch breakage on trees
occurs when the air is warm and humid
after sunset, the air temperature drops, and the atmosphere is unable to contain the amount of water it held during the daytime. The water then precipitates out over the area in small droplets called dew
can be a factor in the spread of diseases in turf grass
What can high auxin concentrations be used for?
What are they used for in commercial agriculture?
To prevent fruit on ornamental trees when the fruit is undesirable feature.
In commercial ag synthetic auxins are used to defoliate plants before harvest, prevent sprouting of potatoes in storage, and prevent premature fruit drop in orchards.
a second group of hormones
associated with stem elongation
other effects: breaking dormancy of seeds, buds, and tubers and inducing flowering in plant that normally require vernalization or a specific photoperiod.
Used in greenhouses to form tall treee-form fuchsias and geraniums form cuttings because of their stem-elongation ability.
Plants that are able to to survive temperature lower than freezing are called frost-hardy
some houseplants and many tropical plants suffer from chilling injury at temperatures less than fifty degrees F. this is why bananas turn black in the fridge.
For temperate-zone fruits such as apples and cherries, an adequate number of cold days per winter, called the plant's chilling requirement
Growing degree requirement
each crop also needs a certain number of adequately warm days in order to mature
A baseline temperature is subtracted from the average temperature for a given day
Hoar frosts vs black frosts
Hoar Frosts: crystal depositing frosts
they occur when moisture from humid air condenses onto the plants because of the drop in temperature
Black Frosts: if the moisture content of the air is low, the air temperature can reach freezing without moisture condensation, but plants will still be injured
the freezing of the soil causes the water contained in it to expand, this may cause a condition called frost heaving, in which the soil pushes up in chunks from around the roots of plants leaving deep cracks over the root area.
decrease in temperature of a wet object when water evaporates form its surface
may determine how well a plant will grow
defined as the amount of water the air contains relative to the amount it is capable of holding at that specific temperature
the higher the temp, the greater the amount of water the air can hold
Duration, intensity, and quality affect growth of outdoor and indoor plants and may control flowering.
duration depends on distance from the equator
Areas in the home can be categorized into three categories:
1. full shade: where the sun rarely shines directly
2. Partial shade/partial sun: sunlight about 1/3 to 1/2 of the time
3. Full sun: on the south sides of houses or where there are no trees shrubs, or structures that block the light
Ocean wind limits number of plants that can be grown near the shoreline
Desert winds increase the rate of moisture loss from the soil and plant leaves
subzero winds damage evergreens by removing moisture from the foliage, essentially freeze-drying it
Natural factors modifying climate include:
distance from the equator
nearby presence of large bodies of water
the higher the elevation of an area, the colder the average year round temperature
sloping terrains also can vary several degrees in temperature from the top portion of the slope to the lower part or valley. Cool air, which is heavier than warm air, will flow down a slope and collect at the bottom, a phenomenon called air drainage.
Bodies of water
larger bodies of water absorbs heat in the summer, making adjacent land cooler and gives it off in the winter raising the temperature
air pollution can be composed of both gases and small airborne pieces of matter; combining and becoming smog
smog affects plant growth by temperature modification. acts like an insulation layer over an area and prevents heat from escaping to the atmosphere. decreases the intensity of light, giving plants less light form which to manufacture carbohydrate.
Main way smog affects plant growth is through foliage injury by toxic gases.
small areas that have slightly different climate characteristics than the surrounding land. many be less windy, shadier, moister, warmer, or in any other way different form the typical climate.
Outdoor Microclimate: example is a frost pocket, or under a tree where it is shadier and cooler
Indoor Microclimate: Upstairs compared to a downstairs in a house. north side compared to the south side of a house
Plant adaptive strategies
desert plants store water in their leaves and can protect themselves from excessive sun exposure.
at high elevations both cold temperature and drying winds become factors in plant survival.
the elevation at which trees can no longer grow because of climate extremes. But other plants do grow
USDA plant hardiness zones
maps showing zones of minimum winter temperatures in the U.S. and Canada
Eleven zones are outlined, ranging form completely frost-free areas in Florida, Texas, and California to negative fifty degrees in Canada.
American Horticultural Society Heat-zone map
The USDA plant heat zone map addresses plant hardiness in excessively hot temperatures instead of excessively cold temps.
by the average number of days per year that the areas experience temps over 86 degrees F.
How are mineral soils classified?
by the size and quantity of mineral particles present in the soil.
From clay to silt to sand
including muck and peat
contain predominately decaying organic matter with smaller amounts of mineral components.
Generally found in small pockets in the north central and northeastern sections of the United States and Canada as well as in the Everglades region of Florida.
very fertile, but do not respond in many respects in the same manner as mineral soils.
often referred to as heavy soils composed primarily of platelike clay particles.
small spaces between clay particles (pore spaces) account for one of the main properties of clay soils- slow water and air movement into and out of the soil
property of clay soils attributable to the flattened shape of the particles is plasticity. This the property of clay responsible for its being sticky and moldable when wet and hard and cloddy when dry.
or light soils
do not retain moisture well; nor do they expand and contract, or compact readily
CEC is low
large particle size
possess qualities of both sand and clay proportional to the relative amount of clay or sand in the loam soil
ideal for most plants
will absorb a large quantity of water and not require frequent irrigation, yet dry enough to be workable in a shorter amount of time than a clay soil
hold more nutrients than do sandy soils
Soil texture triangle
a graphic representation of the percentage combinations of the three basic types of soils in natural soil and the the type of solid formed by each combination
Organic Matter in the soil
is the result of vegetative matter such as leaves and roots and animal products such as manure returning tot he soil and decomposing.
In sandy soils, organic matter increases water and nutrient-holding capacity
in clay soils it improves drainage and air movement
clay particles have a tendency to lie very close together and exclude air
the clumping together of soil particles into large groups
when organic matter decomposes, the resulting humid acid acts as a glue and casuist the clay particles to clump together loosely.
is the relative capacity of the soil to attract and hold nutrients (cations) on the surface of the soil particles.
the ability of a growing medium or soil to attract and hold nutrients
Soils with poor CEC
the numbers of cations each sand particle can attract is quite low
Soils with high CEC
such as clays or those high in organic matter, a very large quantity of nutrients can be held by each soil particle
Fertilizers and CEC
fertilizers need to be applied less frequently to soils high in CEC because of the nutrient storage capabilities.
fertilization can be reduced in high CEC soils by using fertilizers with nitrogen or urea
Cohestion vs Adhesion
Cohesion: the attraction of identical molecules for each other, for example the cohesion of water molecules
Adhesion: the attraction of liquids for solids, for example, the attraction of water for soil
Permanents wilting point
the only water left in the soil is hygroscopic water, which is held too tightly by the soil particles for plants to remove. Thus, available water plant growth is that water between field capacity and the permanent wilting point.
the layers in soil. They can be distinguished by the change in color between the layers.
the topmost horizon is called the A horizon which corresponds with the topsoil
B and C horizons are the subsoils with are low in organic matter and relatively infertile
hardpan- a layer of compacted soil that slows or stops the movement of water and air and the growth of roots into lower layers. can occur naturally or the result of heavy equipment moving over the soil.
the movement of soil par tiles from one place to another and is a process that is detrimental to the fertility of the soil.
water and wind are usually the agents of the movement with the soil either being washed by heavy rain or improper irrigation or blown away by the wind
Large + animals include mammals like gophers and mice, plus burrowing insects such as crickets, beetles that tunnel and brings subsoil to the surface on a continual basis
pH of a soil
is a measure of its acidity or alkalinity
measured on a logarithmic scale that runs from 0 to 14.
7 is neutral
optimum range for the majority of plants is 6.5 to 7
What is used to raise the pH of soil
What is used to lower the pH of soil
sulfur or aluminum sulfate
or by using organic amendments such as oak leaves, pine needles, or sphagnum moss that are acid-forming
resistant to pH change
soils with a high buffering capacity will require larger quantities of pH-adjusting materials than those with a low buffering capacity.
a material added to soil to improve physical properties such as drainage, CEC, aeration, and water retention.
is composed of partially decomposed plants and is made from rotted garden refuse such as weeds, grass clippings, fallen leaves, and plant clippings.
material should be kept damp by sprinkling with water as necessary
are known to be used by plants are classified for was of discussion into two groups:
used in fairly large quantities by plants:
trace elements, used in small quantities include:
What happens when nitrogen is lacking?
What does it stimulate?
plants grow slowly and loose their deep green color, especially on lower leaves.
stimulates rapid vegetative growth, disadvantage of stimulating leafy growth
What does phosphorus influence?
flowering and fruiting, root development, disease resistance, and maturation
because it is insoluble, it will remain where it is placed and will not leach through the soil
What is potassium essential for?
essential for starch formation, movement of sugars, formation of chlorophyll, and flower and fruit coloring
derived from decomposition of plant and animal products
include blood and bone meal, manure and sewage sludge
manufactured using raw materials such as natural gas and phosphate rock
more concentrated than organic fertilizers
can be fast or slow release
the series of transformation nitrogen undergoes in the environment
Nitrogen comprises about 70% of the atmosphere
Legumes with the aid of bacteria that live in nodules on their roots, are able to enrich the soil by fixing atmospheric nitrogen found in the air spaces in the soil
Most common form of fertilizer
slow release because nutrients need not soluble in water
3 categories based on numbers of NPK on fertilizer bag
Balanced fertilizers: all the same 8-8-8
Complete fertilizers: contain some of each 5-10-15