canopy photosynthesis, evapotranspiration, leaf nitrogen, and transcription profiles of maize in...
TRANSCRIPT
Canopy photosynthesis, evapotranspiration, leaf nitrogen, and transcription profiles of maize in response to CO2 enrichment
Soo-Hyung Kim, Richard C Sicher, Hanhong Bae, Dennis C. Gitz, Jeffrey T Baker, Denis J. Timlin and Vangimalla R. Reddy
What does the title tell you?
Why are there so many authors?
Reading a scientific paper
2
Soil-Plant-Atmosphere Research Chambers
• Enclosure of a plant canopy
• Control– CO2
– Temperature– Relative humidity– Fertigation
• Monitor– Canopy photosynthesis– Canopy evapotranspiration– Canopy temperature– Soil moisture– Root growth
Chambers cost ~$120,000 each and there are 12 in this facility at Beltsville MD.
BIOL424/ESRM478 3
Tubes used for Measuring Root Growth
BIOL424/ESRM478 4
How do scientists read a paper?
Abstract
Discussion
Captions and their headings
Introduction
Parts of the results
Parts of the methods
Three things about this paper:
1. The basic conclusions
2. Are the conclusions justified?
3. The logic of the study
No change in photosynthesis
Increased WUE
1. The basic conclusions
Increased CO2 concentration
No difference in biomass
Decreased Nitrogen uptake
Reduced number of stomata
Reduced transpiration
2. Are the conclusions justified?
Strengths:
They give you an empirical result (no
difference in biomass) and research
reasons why that result was obtained.
They attempt to be broad in scope in
researching the processes. They use
transcription profiling as well as measures
of canopy and leaf photosynthesis.
Some weaknesses
Only three replicates – low power
e.g., page 592
“The number of tillers per plant was 1.52 and 2.06 (P = 0.08) in the ambient and elevated Ca treatments,
respectively.”
Why the major result (enhanced WUE) has no effect on
yield is not really explained.
The microarray data is only a partial representation.
The statistically significant difference in leaf N content 3.0
(elevated) to 3.3% ambient is quite large but its effect is not
explained.
3. The logic of the study
The study is basically confirmatory the results
obtained were all suggested in the introduction.
The major addition is that photosynthesis is
measured continuously using the SPAR chambers.
Some points of explanation
Leaf photosynthesis measurements are often poorly correlated with yieldwhy?
“fertigated”
DAP days after planting
Silking
Feed-forward, feed-back proportional-integral-differential control
Condensate removal humidity measurement
A/Ci and A/Q response determinations
Liquid nitrogen
Bonferroni adjustmenta correction of the level used in statistical testing when multiple comparisons are made.
Regression analysis