Plant Growth and Development Part I I 1
Simply defined as: making with light Chlorophyll is needed (in the cells) to trap light energy to make sugars and starches Optimum temperature: 65 o F to 85 o F Photosynthesis 2
Most Photosynthesis Occurs in the Leaves Anything that interferes with the integrity of the leaves interferes with photosynthesis Diseases and nutrient deficiencies Insects Drought Some pesticides 3
Plant Growth and Development Plants need: Gas Exchange, Water, Proper Temperature, Light, Nutrients Stomate Stomata Lenticels 4
Photosynthesis VS. respiration Photosynthesis Light Carbon dioxide + water = oxygen + sugar CO2 + H20 (Light) = O2 + CHO Respiration Sugar + oxygen = carbon dioxide + water + energy CHO + O2 = CO2 + H2O + Energy Respiration occurs both day and night and is essential in the building of cells regardless if it is a plant or an animal 5
Respiration, Photosynthesis & transpiration Photosynthesis Light Carbon dioxide + water = oxygen + sugar Respiration Sugar + oxygen = carbon dioxide + water + energy Transpiration Similar to evaporation Water movement Cools the plant Interesting note: If humidity is decreased, about 90% of the water taken up through the roots is lost through the atmosphere! 6
Gas Exchange in the root Zone Never an excess, only a deficiency Deficient in: Compacted soils Heavy traffic Soil worked that is too wet Heavy soils High clay content Water-logged soils Overwatering High water table 7
Plant Growth and Development Plants need: Gas Exchange, Water, Proper Temperature, Light, Nutrients 8
Water Water is necessary for: Photosynthesis Manufacture of carbohydrates Absorption of nutrients from the soil (through root hairs) Transport of nutrients throughout the plant (through xylem) Cooling the plant surfaces Produced through respiration 9
The root system of a 16 year old apple tree 10
A tree s root system 11
Root Distribution and Absorption 12
Root Distribution in the Landscape Kind of Plant Effective Depth Effective Spread Lawns ~4-6 inches Network Vegetables and Flowers Trees and Shrubs ~6-12 inches 1 10 feet ~8-10 inches 1.5 2 X the dripline 13
Drip line Feeder roots Take up nutrients and water Smaller and relatively shortlived compared to anchor roots 14
Proper watering of trees 15
Plant Growth and Development Plants need: Gas Exchange, Water, Proper Temperature, Light, Nutrients 16
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USDA Hardiness Zones 19
It s not only the Cold USDA Hardiness Zones speak only to Cold Zone 4 in Maine has conditions different from Zone 4 in Montana Other factors affecting plant adaptability Soil ph Salinity Annual Precipitation Relative Humidity Wind Intensity of Sunlight/Elevation Temperature shifts 20
Some Cardinal Temperatures -40 F = Well hardened hardy species survive 15 F = Roots of most plants die 40 F = Cool season crops show chilling damage 45-55 F = Warm season crops show chilling damage 21
Some Cardinal Temperatures 55-75 F = Rapid growth of most plants 85-90 F = Practical growth ceases 90 100 F = Heat Stress Damage 110 +F = Death of most plants 45 F = Minimum practical threshold for growth 22
Degrees Mean Air and Soil Temperatures - Bozeman 45 F = Minimum practical threshold for growth 80 70 60 50 40 30 20 10 Jan Mar May Jul Sep Nov 0 Growing Season 23
Heat Stress Temperature in Excess of 85 F High Light Intensity (concrete, white house) Photodegradation of Chlorophyll Low Soil Moisture As soil dries, plant undergoes water stress, transpiration lowered, leaf overheats, low nutrient uptake Respiration exceeds Photosynthesis 24
Desiccation Winter Damage Low Relative Humidity Frozen Soil Drying Winds Most common on: Shoot tips Evergreens (Scorch) DEEP WATER IN THE FALL. PROTECT FROM WIND AND SUN. 25
Plant Growth and Development Plants need: Gas Exchange, Water, Proper Temperature, Light, Nutrients 26
Electromagnetic Spectrum and Photosynthesis Adapted from W. J. Kaufmann, "Universe", [Freeman:New York].) 27
Plants absorb mainly red and blue light University of Florida 28
Leaves Plants reflect mainly green light 29
Light Quality and Duration Insufficient red and blue light Etiolation Etioloated Very poor growth Spindly, weak Chlorosis North window North aspect Planting under a tree House plants in winter Spindly garden or flower transplants 30
Excess (Excess Sunlight) Excess Light Photodestruction of Chlorophyll (Chlorosis) Not allowing sufficient time for acclimation; planting near highly reflective surfaces Necrosis Combination of high temperature and light intensity 31
Photoperiod Light duration that causes morphogenic (structural) changes in the plant 32
Light Duration = Photoperiod Duration of light affects flowering Each plant may have a critical daylength (nightlength) to form bulbs, tubers, stolons, or flower buds Short-day plants (Poinsettia) Long-day plants (Viola) 8 hrs light 16 hrs of light 33
Long-Night plants Short-Day Plants Require a period of darkness uninterrupted by light 34
Short-night plants Most summer flowering plants Long-Day Plants 35
Day-Neutral Plants Responds regardless of day length 36
Photoperiod Explained Hours of Light 8 9 10 11 12 13 14 15 16 Short-day plants flower Long-day plants flower Day-neutral plants flower 37
Plant Growth and Development Plants need: Gas Exchange, Water, Proper Temperature, Light, Nutrients 38
Nutrients (Review) Usually supplied by soil and fertilizers Insufficient soil oxygen, water, and temperature interferes with root growth. Roots that are not growing cannot absorb nutrients Nutrient deficiencies can interfere with chlorophyll synthesis; plant growth suffers Nutrient pseudodeficiencies can be induced by poor root growth 39
END Questions? 40