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Environmental Requirements for Plant Growth. Unit 4 Introductory Horticulture. Light. Intensity: Brightness. Foot-candle is the form of measurement Day-length or Photoperiod: time in light Long day: summer annuals (marigolds) Short day: short photoperiods (poinsettia)
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Environmental Requirements for Plant Growth Unit 4 Introductory Horticulture
Light • Intensity: Brightness. Foot-candle is the form of measurement • Day-length or Photoperiod: time in light • Long day: summer annuals (marigolds) • Short day: short photoperiods (poinsettia) • Color: red spectrum -> blue spectrum plants need both, sun has both
Temperature • Varies from plant to plant • Sun lovers can take high temps with plenty of water and humidity • Greenhouse temp • Germination 65-75oF • Growth 55-65oF
Water • Necessary for 13 of 16 nutrient uptake • Growth and Maintenance • Photosynthesis • Sap – transport nutrients • Transpiration – cooling • Turgor – plant shape due to cell shape, opposite of turgor is wilt
Water (continued) • Methods and Frequency • Infrequent, thorough watering is best • Container plants: bottom watering is best • Encourages root growth • Dry soil helps reduce disease
Humidity • 40-60% is ideal • Cold winter days and hot summer days humidity is too low • Plant misters can be used
Media • Soil (natural media), Artificial, Hydroponics (no media) • Support the plant • Consistency of volume – wet or dry • Adequate porosity (drainage, aeration) • Provide nutrients (13 needed from soil) • Correct pH for plant (most plants 6.5-7)
Nutrients • Plants need 16 nutrients • Organic macro nutrients • Carbon, hydrogen, oxygen • Essential nutrients • Nitrogen • Phosphorus • Potassium
Sterilization (Applies to Media) • Free of disease, weed seeds, parasites, insects • 180oF for 30 minutes – steam dry heat • Chemical sterilization – methyl bromide gas • Steam heat – commercial greenhouse • Chemical – commercial greenhouse
Insects and Diseases • Sources and Prevention • Media: sterilize • Infected Plants: buy good quality plants from reputable greenhouses • Watering: bottom watering whenever possible, avoid splashing • Controls • Insects: spray, dip, discard • Weeds: pull, spray • Disease: discard