Environmental Requirements Plant and Soil Science

What would occur if plants had an inadequate amount of water supply? Question? What would happen if the plants had an over abundance source of water supply? What would occur if plants had an inadequate amount of water supply?

Shortage or Excess of Water 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

Shortage or Excess of Water The Effects of Water Shortage: Cause plant stress More susceptible to diseases and insects Slow downs photosynthesis Wilting: The loss of water pressure in the plant, causing limpness of the plant tissue Death of the plant

Shortage or Excess of Water The Effects of Excess of Water: Cause plant stress Reduce oxygen levels for plant and root growth High soluble salt accumulation Death of plant

“Plant are Needy for Water?” ACTIVITY LAB SHEET “Plant are Needy for Water?”

Efficient Use of Water The amount of water required depends on several factors: The type of crop Stage of the plant The season of the year The soil or growing medium The method of fertilization being used Watering may be reduced if the weather is cloudy Small volumes of water cause serious reduction is soil Proper methods eliminate buildup of high levels of soluble sales.

Efficient Use of Water Fertilizers Type of soil Season Fertilizer Stage of growth Type of plant

Respond Plants: How is the Color, Intensity, and Duration of Light? Environmental Factors

Light The growth and development of floriculture crops is dependent on light energy. Light energy enables plants to make food through the process of photosynthesis.

Light Color 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 Spectrum.

Electromagnetic Spectrum                                                                                                     <>

Light Color Sunlight contains a complete blend of visible colors including, red, orange, yellow, green, blue, and violet. The rays of visible light falls between, 380 and 780 nanometers. Each color has a different range of wavelengths.

Light Color Light is composed of particles called, Photons. Photons carry with them energy The energy level increases as the wavelengths become shorter. Example: Blue light has a shorter wavelength than red light, & therefore has a higher energy level.

Light Color 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.

Light Color 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.

Light Color Blue: Red: Reduces stem length Increases branching Promotes stem strength Improves leaf & flower color Red: Promotes seed germination Seedling growth Stem elongation

Light Color A wavelength that is important in plant growth & development is Far-red light Far-red light triggers a shade avoidance response. Stems stretch and become weak while the leaves become thinner and wider.

Discuss the Plant Responses to Light Duration

Light Duration 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.

Light Duration Different plants respond differently to the length of light. Short-day plants (Long-night period) Long-day plants (Short-night period) Day-neutral plants (unaffected)

Short Day Plant light dark critical day length 24 hours No Yes No Flowers?

Long Day Plant light dark critical day length 24 hours Yes No Yes Flowers?

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

Light Intensity Involves brightness. Measured in foot candles Is the amount of light distributed by 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 Supplement lighting is valued in greenhouse operations located in low light regions. There are numerous light sources: Incandescent Lights Florescent Lights Metal Halide Lamps Low/High Pressure Sodium Lamps

Describe the Effects of Temperature on Greenhouse Production.

Temperature 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.

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

Express the Theory Behind DIF

DIF 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, DIF.

DIF DIF can be positive, negative, or zero. Positive DIF, is when the day temperature is higher than the night temperature. Negative DIF, is when the day temperature is cooler than the night time temperature. Zero DIF, is when both day/night are identical in temperatures.

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

Advantages & Disadvantages of DIF Stem elongation Can be used in place of Growth retardants Disadvantages: Application is not always possible Result in higher heat and cooling costs

Explain How Air Quality Influences Plant Growth

AIR 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.

Carbon Dioxide Levels CO2 levels can drop significantly when vents are closed, thus slowing down photosynthesis. Ventilation helps replenish CO2 Supplement CO2 can be added Results in higher quality crops Shorter production time Usually added between 9:00 am-3:00pm

Humidity 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

Explain the Importance of Water Quality

Water Watering is the most important cultural practice Everything depends on H2O Water carries material through the xylem and phloem Water makes up a large % of the cells, tissues, and organs.

Water 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 Wilting: Is a dropping condition resulted in loss of turgidity.

Water Water must be given to plants when needed. Timing is critical Frequent 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

Water Quality 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

Irrigation Methods There are numerous irrigation methods Hand watering Spaghetti tubing Drip Irrigation Ebb and Flood method Capillary Mats Saucers Irrigation boom Overhead Sprinklers Intermittent mist system

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