Temperature & Respiration

A/H 100G

J.G. Mexal

HORT Humor

Take Home Quiz (due Monday 2/27/06)

What will be the impact of global climate change to:

• Natural ecosystems

• Agriculture in the southwest

• Urban landscapes, esp. golf courses– Discuss these in terms of near-term

consequences (10-20 years) and long-term (> 30 years)

What is ‘Respiration’?

• The conversion of stored energy (sugar) into metabolic energy (ATP)

• Occurs in mitochondria• Requires sugar• Generates ATP + CO2

The parts of a cell

Ps & Rs Comparison

Photosynthesis• Occurs only in green cells• Occurs in chloroplasts • Occurs only in light• Requires light, CO2, H2O• Produces O2 and sugar• ATP produced by

photophosphorylation (used to make sugar)

• Results in biomass gain

Respiration• Occurs in all living cells• Occurs in mitochondria• Occurs 24/7• Requires O2 and sugar• Produces CO2, H2O• ATP produced by

oxidative phosphorylation (‘burning’ sugar to make other products)

• Results in biomass loss

Temperature Effects on Ps & Rs

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0 10 20 30 40 50

Photosynthsis

Respiration

Temperature (C)

Relative Response (%)

Temperature Effects on Ps & Rs

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Photosynthsis

Respiration

Temperature (C)

Relative Response (%)

Net Ps

Terms

•Cool season crops•Warm season crops•Cold-hardiness•Dormancy

•Endo-•Eco-•Para-

•Chilling requirement•Growing degree day GDD)

•Stratification•Scarification•Vernalization•Heat-zone map•Hardiness zone map

Cool season crops

• Prefers air temperatures: 20-25oC– Soil temperatures: 15-22oC

• Crops:– Lettuce − Kentucky bluegrass– Cole crops − Christmas trees– Carrots − Wheat– Spinach − Barley

Warm season crops

• Prefers air temperatures: 25-35oC– Soil temperatures: 20-28oC

• Crops:– Tomato − Bermuda grass– Sorghum − Corn– Soybean − Chile– Afghan pine − Pineapple

Cold-hardiness

• Definition: ability to survive temperatures below 0oC.

• Function of tissue, season, growth stage– Shoots <-40oC − Roots ~ -10oC

• N.B. Chilling injury is injury to tropical fruits caused by temperatures between 0-5oC

Basic Plant Biology Factors Affecting Acclimation-Size

Spring• Buds = -3o

• Cambium = -4o

• Roots = -4o

• Seedling = -3o

• Germinant = -2o

Winter• Buds = -25o

• Cambium = -50o

• Roots = -10o

• Seedling = -30o

Basic Plant Biology Factors Affecting Acclimation- Genetics

Tolerant• Pinus pinea

– Shoots = -40oC– Roots = -10oC

Intolerant• Eucalyptus

camaldulensis– Shoots = -10oC– Roots = -3oC

Basic Plant Biology

Mesquite/ April 2003

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LT50

LT10

LT90

Dormancy & Cold-hardiness Cold - Hardiness of Apple Blooms

Approximate Calendar Date

LT50 (oC)

Dormant

Silver Tip

12mm Green

Green Tip

Tight Cluster

Full Pink Full Bloom

Growing Degree Hours (oC)

LT

50 (

o C)

Photos by:

Basic Plant Biology Cold - Hardiness of Apple Blooms

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01000 2000 3000 4000 5000 6000 7000

Basic Plant Biology How a Tree Grows• Dormancy-lack of visible growth

– Ecodormancy- environmental stress induced-

• Growth resumes when stress removed

– Endodormancy- requires chilling• Growth resumes after chilling requirement met

(h between 0-10oC), and sufficient GDD accumulate

– Paradormancy- regulated by other buds• Remove the controlling bud and ‘whalaa’

Dormancy & Cold-hardiness Dormancy of Apple Blooms

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1.0

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-1.0

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Temperature (oC)

Chilling Units Growth Units

Growing degree days (GDD)

• Growing degree days (GDD) is a measure of temperature requirements for plants and can be used to estimate growth and development.

• The basic concept of growing degree days is that plant development will occur when temperatures exceed a base temperature.

Growing degree days (GDD)

• Corn: the maximum temperature plus the minimum temperature in a day divided by 2 minus 50.

• Fifty is selected as the constant because corn grows little at 50°F or below.

• 86°F is the maximum temperature

Growing degree days (GDD)

• Example: If a low temperature was 60°F and the high was 90°F, the GDD would be 60 + 86 = 146 divided by 2 = 73 – 50 = 23 GDD.

National Climate Zone Map

E Gregory McPherson <egmcpherson@ucdavis.edu>

Plant Hardiness Zone Map

USDA Hardiness Zone Map

Plant Heat Zone Map

Nursery Industry

Heat-Zone Map/ AmHortSoc

Days/yr> 86F

7-14

14-30

30-45

45-60

60-90

90-120

120-150Zone 9

New Mexico Maps

Zone 9

Days/yr> 86F

7-1414-3030-4545-6060-90

90-120120-150

Seed Dormancy

• Stratification– Overcoming physiological dormancy by

exposure to cold temperatures (wet or dry)

• Scarification– Overcoming physical dormancy by

mechanical abrasion• Mechanical• Chemical (acid)• Thermal (hot water)• Percussion (certain species)

Vernalization

• Chilling to induce transition from vegetative growth to reproductive growth

• Examples:– Winter wheat– Onions (biennial)– Bulbs (daffodil, tulip)

Things to know:

•Cool season crops (T & e.g.)•Warm season crops (T & e.g.)•Cold-hardiness (definition, LT50)•Dormancy

•Endo-•Eco-•Para-

•Chilling requirement•Growing degree day GDD)

Things to know:

• Stratification (e.g.)

• Scarification (e.g.)

• Vernalization (e.g.)

• Heat-zone map (what it means)

• Hardiness zone map (what it means)

Infrared Surface Temperature Influenced by Surface Cover

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TurfAsphaltArtificial Turf

Military Time (hr)

Temperature (oF)