Lecture 4: Crop Resource Use Flashcards
Examples of abiotic factors
light
atmospheric CO2
temperature
water
nutrients
other soil constraints
Examples of biotic factors
weeds
disease
insects
soil microorganisms
intraspecific competition
photosynthetically active radiation
the wavelengths that chlorophylls can absorb
typical growth curve
as plant gets bigger, it needs more resources
What happens if plants get too much light
causes plants to bleach and burn
How can light be minimized
shading
agrivoltaics (solar panels)
How to prevent too little light?
intercropping (varying height)
breeding plants to be thinner
photoperiodism
a biological response to a change in the proportions of light and dark in a 24-hour daily cycle
3 types of plants (day lengths)
short-day (light period shorter than critical period)
Long-day (light period longer than critical period)
Day-neutral (will flower regardless of daylength)
harvest index
ratio of grain yield/total biomass
C3 photosynthesis
Carbon dioxide is added to a phosphorylated 5-carbon sugar RuBP and catalyzed by the enzyme Rubisco. The resulting 6-carbon compound breaks down into 2 molecules of 3-phosphoglyceric acid
what does the photorespiration process use and release
uses O2 and releases CO2
When does photorespiration increase and decrease
increases with light intensity and high temps, and decreases with increasing atmospheric CO2 concentrations
C4 photosynthesis
carboxylating enzymes are phosphoenolpyruvate carboxylase, followed by rubisco and photosynthesis is more efficient
what are C4 plants better adapted to
high heat and dryness because they have smaller stomata to prevent water loss
what is the anatomy of a C4 plant
kranz anatomy
Crassulacean Acid Metabolism Photosynthesis (CAM)
Uses both Calvin and C4 pathways (temporally separated). CO2 is fixed at night by PEP carboxylase and oxaloacetate is reduced to malic acid to store in vacuole.
IN day malic acid losses C and is used in the cycle
enzyme activity occurs between ______ and ______
5 and 30 C
what happens when it is too cold
enzymes don’t work and ice crystals cause tissues to break down
vernalization
requiring a period of cold temperatures to trigger the flowering process
what happens when it is too hot
plants wilt or die because they don’t have enough water or cant transpire fast enough
heat stress can speed up _________ causing __________
development, early senescence
examples of negative effects of heat stress
reduce in energy investment in growth and reproduction
abnormal pollen development/ ovary sterility
Abortion of grains
Temperature stress in Australia
They don’t really have snow, so they seed the same time as us, but into colder temps
“long juvenile” trait
modified growth stages to adapt plants to different environments and remove sensitivity to photoperiod
what plant was converted to long juvenile
Soybean
water in plants
essential for life
photosynthesis
solvent
65 to 90% water content
flooding
creates anaerobic environment, causing toxicity, pathogens, and denitrification
aridity
long-term climatic phenomenon
drought
temporary phenomenon
field capacity
water remaining in the soil after it has been thoroughly saturated and allowed to drain freely
permanent wilting point
the moisture content at which plants wilt and fail to recover
available water capacity
the difference between field capacity and permanent wilting capacity point
factors that affect available water capacity
soil texture
rock fragments
organic matter content
compaction
salinity
restrictive layers
Dryland Systems
infiltration
rhizostorage
consumptive
transpiration
assimilation
biomass
yield
nutrients obtained from air and water
C, H, O
Macronutrients
N, P, K, S
Secondary elements (nutrients)
Ca, Mg
Micronutrients
Fe, Cu, Mn, Zn, B, Mo, Cl, Co, Pb
