Environmental Environmental RequirementsRequirements

Plant health and development depends on water.

If the main source that makes up 90% of its source is limited or supplied in an over abundance, the plant will not be able to adequately achieve its crop yield.

Plants are not the same and do not all require the same amount of water to survive.

There are many factors that allow plants to tolerate shortage or excess amounts of water. Deep, well-developed root system Waxy leaf surface Shiny or light colored leaves

The Effects of Water ShortageThe Effects of Water Shortage: Cause plant stressCause plant stress More susceptible to diseases and More susceptible to diseases and

insectsinsects Slow downs photosynthesisSlow downs photosynthesisWiltingWilting: The loss of water pressure : The loss of water pressure

in the plant, causing limpness of the in the plant, causing limpness of the plant tissueplant tissue

Death of the plantDeath of the plant

The Effects of Excess of WaterThe Effects of Excess of Water: Cause plant stressCause plant stress Reduce oxygen levels for plant and Reduce oxygen levels for plant and

root growthroot growth High soluble salt accumulationHigh soluble salt accumulation Death of plantDeath of plant

LAB SHEET

““Plant are Needy for Water?”Plant are Needy for Water?”

The amount of water required depends on several factors: The type of cropThe type of crop Stage of the plantStage of the plant The season of the yearThe season of the year The soil or growing mediumThe soil or growing medium The method of fertilization being usedThe method of fertilization being used

Watering may be reduced if the weather is Watering may be reduced if the weather is cloudycloudy

Small volumes of water cause serious Small volumes of water cause serious reduction is soilreduction is soil

Proper methods eliminate buildup of high Proper methods eliminate buildup of high levels of soluble sales.levels of soluble sales.

Season

Fertilizers

Stage of growth Type of plant

Type of soilFertilizer

Environmental Environmental FactorsFactors

The growth and development of floriculture crops is dependent on light energy.

Light energy enables plants to make food through the process of photosynthesis.

Visible light (light we see) is a small segment of all the radiant energy (rays) given off by the sun.

The wavelengths of the different rays are measured in nanometers.

Based on their wavelengths, the rays have been placed on an, Electromagnetic SpectrumElectromagnetic Spectrum.

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Sunlight contains a complete blend of visible colors including, red, orange, yellow, green, blue, and violet.

The rays of visible light falls between, 380380 and 780 780 nanometers.

Each color has a different range of wavelengths.

Light is composed of particles called, Photons.

Photons carry with them energyThe energy level increases as the

wavelengths become shorter.Example: Blue light has a shorter

wavelength than red light, & therefore has a higher energy level.

The energy carried by the photons is absorbed by objects, such as plants and produces heat.

Through photosynthesis, plants are capable of converting light energy into chemical (food) energy.

Some lights are absorbed and some are reflected.

Objects that absorb all the colors except one color, such as green will appear green.

The light that is reflected has little affect on the object.

In plants, blue & red have the greatest influence on plant growth.

Blue:Blue:Reduces stem lengthIncreases branchingPromotes stem strengthImproves leaf & flower color

Red:Red:Promotes seed germinationSeedling growthStem elongation

A wavelength that is important in plant growth & development isFar-red lightFar-red light

Far-red light triggers a shade avoidance response. Stems stretch and become weak

while the leaves become thinner and wider.

Plants are responsive to the length of time they are exposed to light.

A mechanism in the plant detects the length of the light period.

A plant’s response to the length of light is known as, Photoperiodism.

Different plants respond differently to the length of light.

Short-day plants (Long-night periodLong-night period)Long-day plants (Short-night periodShort-night period)Day-neutral plants (unaffectedunaffected)

Short Day Plant

No No

criticalday length

Flowers?

24 h

ours

light

dark

Yes

Long Day Plant

No

criticalday length

Flowers?

24 h

ours

light

dark

YesYes

Growers control the length of light to bring on one or more plant responses. Keep plant in a vegetative stage of

growth. Encourage Flowering

Involves brightness.Measured in foot candles

Is the amount of light distributed Is the amount of light distributed by a single candle one-foot awayby a single candle one-foot away.

All plants have different terms of light intensity.

Light intensity can influence plant development for better or for worse.

Supplement lighting is valued in greenhouse operations located in low light regions.

There are numerous light sources:Incandescent LightsIncandescent LightsFlorescent LightsFlorescent LightsMetal Halide LampsMetal Halide LampsLow/High Pressure Sodium LampsLow/High Pressure Sodium Lamps

Temperature is an important key factor in plant development and in a number of plant responses

Plant responses speed up as temperature rises & slows down as temperature becomes cooler.

This is because enzymes that drive the reactions are sensitive to temperature.

A term used to describe a temperature requirement that produces a plant response is, Thermoperiodism.

For some crops, a period of cold temperature is required for flowering.

This physiological process is known as, Vernalization.Examples: Easter Lilies & Tulips: Easter Lilies & Tulips

Growers use temperature to control the height of plants.

They do this by managing the difference between the daytime and the night time temperatures.

The mathematical difference between the daytime and nighttime temperatures is called, DIFDIF..

DIF can be positivepositive, negativenegative, or zerozero.

Positive DIFPositive DIF,, is when the day temperature is higher than the night temperature.

Negative DIFNegative DIF,, is when the day temperature is cooler than the night time temperature.

Zero DIFZero DIF,, is when both day/night are identical in temperatures.

EXAMPLES:EXAMPLES:Positive DIF- A day temperature of 78°F78°F and a night temperature of 68°F68°F equals a positive DIF of +10°F+10°F (78-68 = 10). Negative DIF- A day temperature of 65°F65°F and a night temperature of 72°F72°F equals a negative DIF of -7°F-7°F (65-72 = -7).Zero DIF- A day temperature of 70°F70°F and a night temperature of 70°F70°F equals a zero DIF of 0°F0°F (70-70 = 0).

Advantages:Advantages:Stem elongationCan be used in place of Growth retardants

Disadvantages:Disadvantages:Application is not always possible

Result in higher heat and cooling costs

Air has CO2 and O2 that are critical for photosynthesis and respiration.

The ability of air to move in and out of the aid is important in providing O2 for healthy root growth.

Roots need O2 to undergo respiration

Air quality is an ingredient to producing healthy plants.

CO2 levels can drop significantly when vents are closed, thus slowing down photosynthesis.

Ventilation helps replenish CO2Supplement CO2 can be added

Results in higher quality crops Shorter production time

Usually added between 9:00 am-3:00pm

Humidity, which is water vapor, affects plant growth

The growth rate increases under high humidity conditions

High humidity reduces water stress

Low humidity induces water stress

Excess humidity increases diseases

Watering is the most important cultural practice

Everything depends on H2OWater carries material through

the xylem and phloemWater makes up a large % of the

cells, tissues, and organs.

A lack of water puts the plant under stress, thus inhibiting the roots to supply water quickly to replace water transpired.

Sever water loss can cause

WiltingWilting: Is a dropping condition resulted in loss of turgidity.

Water must be given to plants when needed.

Timing is criticalFrequent watering can keep

growing medium to wet, lacking good air exchange

A good rule of thumb is to water the plant thoroughly when they need water and wait until they need water before watering again

A few things to consider with water quality is;

pH of the water Should range of 5.8 to 6.2 is adequate.

Soluble Salts High soluble salts damage roots

There are numerous irrigation There are numerous irrigation methodsmethodsHand wateringSpaghetti tubingDrip IrrigationEbb and Flood methodCapillary MatsSaucersIrrigation boomOverhead SprinklersIntermittent mist system