PBIO 3110

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PBIO 3110 CROP PHYSIOLOGY LABORATORY   Photosynt
hesis and Growth Analysis Results
Interpretation Department of Plant Agriculture
University of Guelph October 24, 2006
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General Purpose

• Getting familiar with instrumentations and
  making measurements

• Conducting experiments and interpreting
  results using course information

• Understanding physiological response of crop
  to environmental stresses

• Knowing what is a meaningful observation

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Objectives and Hypotheses

• To measure the effects of low N availability
  on crop physiological processes

• To quantify the differences of crop response
  to environmental stress between older and
  newer cultivars

Hypotheses there are no differences between low
and high N, and between older and newer cultivars
on leaf photosynthesis and dry matter
accumulation.
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Material and Methods
Crop Corn Pride 5 (old) NK (new)
Soybean Beachwood (old)
OAC Champion (new)
Nitrogen Low 4 mmol-N High 20 mmol-N

Growth conditions Controlled environment
growth room and growth cabinets. (environmental
factor settings, i.e. PPFD, temperature,
photoperiod, moisture)
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Measurements

• 1) Phenology (Stage of
  development)
• 2) Chlorophyll fluorescence
• (dark adapted)
• 3) Chlorophyll fluorescence
• (light adapted)
• 4) Photosynthetic rate
• 5) Stomatal conductance

• Light (PPFD)
• 7) Chlorophyll content
• (SPAD readings)
• Above-ground dry
• matter
• 9) Leaf area
• 10) Respiration rate

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7
High N
Low N
 
 
8
High N
Low N
 
 
9
High N
Low N
High N
Low N
Pride 5
NK
 
 
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Results
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Result Interpretation
1. Difference mean comparison between
N treatments or
cultivars low N vs. high N old cultivar
vs. new cultivar
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Differences between treatment means in
photosynthetic rate of corn
No difference on Oct. 4, but it was higher in
high N on Oct. 11 and 18.
No differences between two hybrids at three
measuring times.
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Differences between treatment means of
above-ground dry matter in corn
DM reduction under low N is 32 and 35 at Oct. 4
and 18, respectively.
Old hybrid produced 25 -37 greater DM than the
new hybrid.
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Crop Growth Rate (Soybean)
a
a
a
b

(W2-W1) 1
Specific Growth Rate (SGR)

(t2-t1) W
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Result Interpretation
1. Difference low N vs. high N old
cultivar vs. new cultivar
2. Variability scatter of the treatment
means or data variation among measurements
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Mean Comparison
DM(g/pl)
C
D
Cultivar
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Variability around four treatment means for
soybean dry matter measured at Oct. 3
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Variability around four treatment means for
soybean dry matter measured at Oct. 17
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Result Interpretation
1. Difference low N vs. high N old
cultivar vs. new cultivar
2. Variability scatter of the treatment means
3. Interaction N treatment x cultivar or G x
E effects
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Interactions response of two soybean cultivars
to low and high N availability
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Interactions response of two corn hybrids to
low and high N availability
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No Interactions response of two corn hybrids to
low and high N availability
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Result Interpretation
1. Difference low N vs. high N old
cultivar vs. new cultivar
2. Variability scatter of the treatment means
3. Interaction N treatment x cultivar (G x E)
4. Relations connections among all measured
parameters
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Connections between traits
Grain yield
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Result Interpretation
1. Difference low N vs. high N old
cultivar vs. new cultivar
2. Variability scatter of the treatment means
3. Interaction N treatment x cultivar (G x E)
4. Relations among all measured traits
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Oral Presentation

• Group 1 (corn) and group 2 (soybeans)
  DM, Leaf area, plant growth rate,
  phenology
• how it related to light interception
• Group 3 (corn) and group 4 (soybeans)
  leaf photosynthesis and respiration
• how it related to DM accumulation
• Group 5 (corn) and group 6 (soybeans)
  
• stomatal and chlorophyll activities
• how it related to leaf photosynthesis