Climate and Adaptation of Agricultural Crops Elements of

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Climate and Adaptation of Agricultural Crops
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Elements of climate most directly affecting plant
growth

• Temperature
• Moisture
• Solar radiation
• Wind, etc.

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Elements of climate most directly affecting plant
growth

• Temperature
• Moisture
• Solar radiation
• Wind, etc.

-- Tropical vs temperate (including tropical high
elevations) -- Soil temperature (affects plant
germination, emergence, root growth)
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Elements of climate most directly affecting plant
growth

• Temperature
• Moisture
• Solar radiation
• Wind, etc.

-- Rainfall frequency and intensity soil
moisture -- Humidity
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Elements of climate most directly affecting plant
growth

• Temperature
• Moisture
• Solar radiation
• Wind, etc.

-- Photoperiod -- Light intensity and shading
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Elements of climate most directly affecting plant
growth

• Temperature
• Moisture
• Solar radiation
• Wind, etc.

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Wind Damage Hurricane Frances
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Wind and Agriculture - Infrastructure
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Wind and Agriculture - Crops
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Elements of climate most directly affecting plant
growth

• Temperature
• Moisture
• Solar radiation
• Wind, etc.

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Adaptations of plants to climatic (physical)
factors determine

• Geographic distribution
• Growing season
• Limits are set by extremes such as killing frost
  vs high temperature.
• Within a geographic location, plants may exhibit
  dormancy at certain times (out of season).
• Dormant stages may require environmental cue
  (higher temp., more moisture) to continue
  development.

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Dormancy and Easter Lilies
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Agricultural climate types recognized by Carroll
et al. (1990)

• Wet tropical (about 5N-5S, 11 months w. rainfall
  gt15 cm)
• Wet-dry tropical (about 5-25NS distinct wet
  and dry seasons
• Cool tropical (gt 1000 m elevation)
• Moist midlatitude (25-55NS, e.g. - eastern North
  America)
• Dry midlatitude (25-55NS, e.g. - central North
  America)
• Mediterranean (some continental coasts 30-40NS,
  wet winter and dry summer
• Arid

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Agricultural climate types recognized by Carroll
et al. (1990)

• Wet tropical
• Wet-dry tropical seasonal moisture
• Cool tropical
• Moist midlatitude seasonal temperature
• Dry midlatitude seasonal temperature
• Mediterranean
• Arid

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Agricultural climate types recognized by Carroll
et al. (1990)

• Wet tropical (about 5N-5S, 11 months w. rainfall
  gt15 cm)
• Wet-dry tropical (about 5-25NS distinct wet
  and dry seasons
• Cool tropical (gt 1000 m elevation)
• Moist midlatitude (25-55NS, e.g. - eastern North
  America)
• Dry midlatitude (25-55NS, e.g. - central North
  America)
• Mediterranean (some continental coasts 30-40NS,
  wet winter and dry summer
• Arid

Gainesville FL 29o40N ??
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Gainesville, FL Weather Summary
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Subtropical some seasonal fluctuation in both
moisture and temperature
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Temperature and Plant Growth(similar pattern for
most physical factors)
Temperature
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Temperature and Plant Growth(similar pattern for
most physical factors)
10 20 30 40
Temperature
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Temperature and other Physical Factors

• Optimum range for plant growth
• Below minimum cant grow
• Above maximum cant grow

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Applications of Temperature Adaptation and
Preferences

• Determines distribution and growing season
• Competition with weeds depends on relative
  adaptation of weed vs. crop plant

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Heat Units

• Over the adapted range, vegetative growth of
  plants increases with temperature
• So crop cycle can be longer at low temperatures
• Often convenient to measure life cycle in terms
  of heat units

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Heat Units

• Heat Unit days or hours of accumulated
  temperature above some threshold (but below max.
  limits)
• Measured in degree-days or degree hours
• Lower temperature is called the threshold or base
  temperature

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Heat Unit (Degree Day) Calculation
Degrees above base temp
Sum over number of days
Tbase min. temp. for plant growth
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Max, Min, Mean, and Base Temperatures
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Mean Temperature can be Estimated from Daily Max
and Min Readings
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Example for Heat Unit (Degree Day) Calculation
Degrees above base temp
Sum over number of days
Tbase min. temp. for plant growth
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Degree Days Sample Calculations
Max. Min. Mean
DD
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Degree Days Sample Calculations
Max. Min. Mean
DD
If mean gt upper limit, round to upper limit If
mean lt base temp., 0 DD
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DD calculations are good approximations, for more
detail can go to hourly temperatures, etc.
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Heat Units and Degree Days

• Good approximations for plant growth, insect
  growth, etc.
• Opposite effect some plants, such as some
  temperate fruits, may require a certain amount of
  chilling days or chilling hours below a certain
  temperature before they can set fruit.

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Plant Growth
Photoperiod
DD
Vegetative stage
Flowering or
Reproductive stage
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Effects of Light on Plants

• Photoperiod (hours of day and night)
• Light intensity (affects photosynthesis)

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Flowering Response to Photoperiod (can end
vegetative growth)

• Short day plants flower only when day length is
  less than some critical value (spring, fall)
• Long day plants flower only when day length
  exceeds some critical value
• Day neutral
• Flowering accelerated by shorter or longer
  nights similar response to short or long day,
  but not complete (most plants)

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Flowering Response to Photoperiod

• Determinate plants vegetative growth stops at
  flowering
• Indeterminate plants vegetative growth
  continues after first flowering, may have
  multiple cycles of flowers and fruit

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Determinate vs Indeterminate Characteristics in
Cowpea
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Soybean short day plant, highly determinate
Scott and Aldrich, 1970
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Soybean Maturity Groups
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Soybean and day length
What if flowering occurs at lt 14 hr ?
Scott and Aldrich, 1970
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Light Intensity Different photosynthetic
pathways allow adaptation to different light
intensities

• C3 Most plants, adapted to various light
  levels, can reach max growth under cooler
  conditions, lower light intensity.
• C4 Many grasses adapted to high sunlight,
  more efficient in photosynthesis and use of water
• CAM some cactus, pineapple adapted to
  water-deficient habitats, deserts.

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C3 vs C4 Plants
C3
C4
Photosynthesis
Light Intensity
Light Intensity
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References

• Text climate, pp. 76-83 light, C3/C4, pp.
  20-22 heat units, photoperiod, pp. 103-107.
• Carroll, R.C., J.H. Vandermeer, and P. Rosset.
  1990. Agroecology. McGraw-Hill, New York, Ch. 2.
• Scott, W.O., and S.R. Aldrich. 1970. Modern
  Soybean Production. S A Publications,
  Champaign, IL.
• Thomas, B.P. et al. 1985. Soil Survey of Alachua
  County, Florida. USDA Soil Conservation Service,
  Washington.
• Tivy, J. 1992. Agricultural Ecology. Longman
  Scientific and Technical, Essex, UK. Ch. 3, pp.
  21-28.