Environmental Factors Affecting Plant Growth

Abiotic factors: non-living factors that affect plant growth, including:
- Temperature
- Light intensity
- Air speed
- Water current
- Humidity
- pH
- Dissolved oxygen
- Salinity
- Nitrate, phosphate, and other plant nutrients
Biotic factors: living factors that affect plant growth, including:
- Living organisms in the ecosystem
Climatic factors: average weather conditions that affect the community in an ecosystem
Edaphic factors: soil-related factors that affect plant growth, including:
- Soil pH
- Minerals
- Moisture
- Humus

Water is essential for plant growth, and plants acquire most of their water from the soil through root hairs
Water is necessary for:
- Photosynthesis
- Maintaining turgor pressure
- Transporting nutrients throughout the plant
Plants lose water through all parts, but most water is lost through the leaves
Plants reduce water loss by closing the stomata

Temperature is the main environmental factor affecting plant growth
Temperature determines:
- Planting dates
- Growing season
- What plants can be grown in a locale
Temperature affects:
- Rate of plant growth
- Plant quality
Hardiness: the ability of a plant to survive outdoors in a given location
Cool-season plants: require cool temperatures to germinate, grow, and mature properly (e.g., pansies, daffodils, peas, spinach, lettuce)
Warm-season plants: require warm temperatures to germinate, grow, and mature properly (e.g., zinnia, tomato, pepper, okra)

Light has three principle characteristics that affect plant growth:
- Quantity (intensity or brightness)
- Quality (different wavelengths of light)
- Duration (photoperiod)
Plants grow best in full sunlight, but some require low light intensity
Red and blue lights are the most effective for plant growth, while green light is reflected by plants and is the least effective
Incandescent lights emit high levels of red and orange light, but produce too much heat to be an effective lighting source for plants
Cool white fluorescent lights are high in blue and encourage leafy growth

Embryophytes: protect embryos on parent body, surrounded by protective tissue, and nourish embryos
Gametangia: multicellular organs that produce gametes (eggs or sperm)
Sporangia: multicellular organs that produce spores
Apical meristems: growing points located at tips of plant structures
Cuticles: waxy coat on plant surfaces above ground
Stomata: pores in leaves and other photosynthetic organs for gas exchange
Vascular tissue: provides support and transport, with two types: xylem and phloem
Secondary compounds: provide defense (toxins, antifeedants), support (lignin), and UV protection (flavonoids)
Sporopollenin: coat on spores and pollen

Abiotic factors: non-living factors that affect plant growth, including:
- Temperature
- Light intensity
- Air speed
- Water current
- Humidity
- pH
- Dissolved oxygen
- Salinity
- Nitrate, phosphate, and other plant nutrients
Biotic factors: living factors that affect plant growth, including:
- Living organisms in the ecosystem
Climatic factors: average weather conditions that affect the community in an ecosystem
Edaphic factors: soil-related factors that affect plant growth, including:
- Soil pH
- Minerals
- Moisture
- Humus

Water is essential for plant growth, and plants acquire most of their water from the soil through root hairs
Water is necessary for:
- Photosynthesis
- Maintaining turgor pressure
- Transporting nutrients throughout the plant
Plants lose water through all parts, but most water is lost through the leaves
Plants reduce water loss by closing the stomata

Temperature is the main environmental factor affecting plant growth
Temperature determines:
- Planting dates
- Growing season
- What plants can be grown in a locale
Temperature affects:
- Rate of plant growth
- Plant quality
Hardiness: the ability of a plant to survive outdoors in a given location
Cool-season plants: require cool temperatures to germinate, grow, and mature properly (e.g., pansies, daffodils, peas, spinach, lettuce)
Warm-season plants: require warm temperatures to germinate, grow, and mature properly (e.g., zinnia, tomato, pepper, okra)

Light has three principle characteristics that affect plant growth:
- Quantity (intensity or brightness)
- Quality (different wavelengths of light)
- Duration (photoperiod)
Plants grow best in full sunlight, but some require low light intensity
Red and blue lights are the most effective for plant growth, while green light is reflected by plants and is the least effective
Incandescent lights emit high levels of red and orange light, but produce too much heat to be an effective lighting source for plants
Cool white fluorescent lights are high in blue and encourage leafy growth

Embryophytes: protect embryos on parent body, surrounded by protective tissue, and nourish embryos
Gametangia: multicellular organs that produce gametes (eggs or sperm)
Sporangia: multicellular organs that produce spores
Apical meristems: growing points located at tips of plant structures
Cuticles: waxy coat on plant surfaces above ground
Stomata: pores in leaves and other photosynthetic organs for gas exchange
Vascular tissue: provides support and transport, with two types: xylem and phloem
Secondary compounds: provide defense (toxins, antifeedants), support (lignin), and UV protection (flavonoids)
Sporopollenin: coat on spores and pollen