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Why do some plant use water
more efficiently than others?
Plant phys
Lecture 1-16-09
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Some Plants have
extensive root system
and usually do well
even under droughtconditions.
Ie. Alfalfa,
Sorghm
Very dry tolerant
Because of extensive
root system
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What is water Use Efficiency or
WUE?
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WUE=EF= Volume used/Value extracted
# water used/unit biomass produced
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what is the characteristic of
crops with high WUE, why?
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High WEU crops are able to produce high
yields under drought condition by keeping
stomates open for longer periods for CO2
fixation.
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How does temperature influence
plant growth?
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Temperature control seed germination
Most seed 10 to 35 C
Temperature needed for flower initiation
Temperature induction and breaking of
dormancy
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What is vernalization?
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Exposing plants to low temperature for a set
period causes flowering when returned to
normal temperature.
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What is a tuber?
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An underground stem
Iie, sweet potato
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Light comes in three forms, what
are they?
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Intensity (brightness)
Duration (how long)
Quality (wavelength)
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How is plant affected by light?
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Plants can grow without light, but cannot
develop without it.
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What is etiolation?
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occurs when plants are grown in either partial
or complete absence of light, and is
characterized by
Deformed leaves
Elongated stems
Yellowing plant (chlorosis)
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What is the part of light that
plant sees?
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Visible light
Violet 390 nam
Blue 400nm
Bluegreen 470 shorter Green 500
Yellow 590
Orange 600 (street light) Red 680
Far red 750 longer
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What is light intensity? How is it
related to plant growth?
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It is the strength and brightness of light.
The more intensity, the light , the more
growth (to a point) and increase Pn to a point.
CO2
limited
600 to 800
grow feed
back
inhibition
Light intensity
growth
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What is photo bleaching?
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When too much light or high light intensity
Leaves turn yellow when sun at its zenith=
2000 Um
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Do plants respond better to
higher or lower intensity of light?
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Plant respond better to lower intensity of
light, Better to double the time and decrease
the intensity.
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How does intensity affect plant
architecture?
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Material shading
Only top leaves are doing the job (Pn) due to incident light
Vents work in 1950 shows that incident radiation is important
for
plant
Lower leaves do not get much light but are shaded by light
above, therefore do not Pn as much.
Leaf morphology (and petiole)
Studies shows that incident radiation is what is impo
toplants.
Corn vertical leaves (increase up to 40%)
The more verticle, the better for lighting
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What is intra canopy lighting?
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A new technology that provides light to leaf at
bottom of column of tree.
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How is quality of light
determined?
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It is determined by wavelength
For example, light in the range of Blue red
wavelength are most important quality of light
for plants.
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Do plant use wavelength in the
range of Blue/ red range?
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They dont use the whole spectrum, but lack
of it will produce physiological disorders in the
plants
i.e. edema, intumescences, galls in leaves
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Distinguish between three types
of plants according to their light
duration requirements forflowering (photoperiod).
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Long day plants 13- 14 hours
Short day plants < 13 14 hours
Day mutual plants will flower regardless
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What is light compensation
point?
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the amount oflight intensity on the light
curve where the rate of photosynthesis
exactly matches the rate ofrespiration. At this
point, the uptake ofCO2 throughphotosynthetic pathways is
exactly matched
to the respiratory release of carbon dioxide,
and the uptake ofO2 by respiration is exactlymatched to the
photosynthetic release of
oxygen.
http://en.wikipedia.org/wiki/Light_curvehttp://en.wikipedia.org/wiki/Light_curvehttp://en.wikipedia.org/wiki/Cellular_respirationhttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Molecular_oxygenhttp://en.wikipedia.org/wiki/Molecular_oxygenhttp://en.wikipedia.org/wiki/Molecular_oxygenhttp://en.wikipedia.org/wiki/Molecular_oxygenhttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Cellular_respirationhttp://en.wikipedia.org/wiki/Light_curvehttp://en.wikipedia.org/wiki/Light_curve
