crops
The sequence of events in nodule formation are as follows:
1. 1. chemical signals exchanged 2. release of bacteria into cortex 3. nodule formation
--- occurs at temperature below optimal for growth and cell membranes become destabilized via --- . --- occurs from formation of intra- and extracellular ice.
1. Chilling injury 2. reduced membrane fluidity 3. Freezing injury
Describe two of the primary factors that determine volume flow rate in the xylem (i.e. what factors could reduce or increase flow rate).
1. Diameter of your conduit - bigger the tube, the more water will flow through it (and vise versa) 2. Viscosity of the fluid and pressure gradient from the very top of the plant to the very bottom (leaves to roots)
Name the three steps in the Calvin-Benson cycle.
1. Fixation (carboxylation)- reduction of CO2 and H2O (5 carbon acceptor molecule) to generate 2 molecules of a 3-carbon intermediate (PGA) 2. Reduction- to 3 carbon carbohydrate (G3P) - 2 enzyme reaction by ATP & NADPH 3. Regeneration- RuBP is regenerated in series of 10 -enzyme reactions with ATP (from light reaction)
Name and discuss (1 sentence each) two opportunities for improving Potential Yield.
1. Improving crop nutrition and increasing rates of nitrogen application; rapid development of optimal LAI or longer lasting max LAI. 2. Breeding for increases in harvest index (example crops are; wheat, rice, maize); shorter stature and stronger reproductive sinks.
The following isotopes are in the highest percentage in our atmosphere:
12C, 14N, 16O
What is the radioactive isotope of carbon?
14C
the shortest wavelength of visible light is approximately
400 nm
PAR encompasses the following wavelengths of light
400-700 nm
Briefly describe whether the difference in electromagnetic radiation received between summer and winter in Florida impacts potential crop production, and why or why not.
??
Which of the following is a final product of the light reactions?
ATP
The boundary layer above the leaf surface:
All answers are correct Usually contains a higher amount of water vapor than the atmosphere above it, Causes some resistance to both water vapor out of the leaf and carbon dioxide movement into the leaf, Is thicker in still air
Meristems are:
All of the above are correct c. Specialized tissues that contain undifferentiated cells. b. Specialized tissues that contain cells known as initials. a. Specialized tissues where growth occurs.
Types of HR include:
All of the answers are correct lift of deep water into dry, shallow soil layers, inverse HR, fog uptake
Which of the answer(s) can maximize WUE?
All of these can maximize WUE d. Full canopy cover b. Humid environments a. Increased photosynthesis
Maximum light interception by a crop is first reached at:
An LAI of 3-4
Define and describe (1-2 sentences) AMF.
Arbuscular Mycorrhizal Fungi: the fungal symbiont produces specialized structures for nutrient interchange with the host inside root cells and establishes a diffuse network of external fine hyphae in soil.
Stomatal conductance and transpiration:
Are de-coupled when boundary layer conductance is low (r is high)
Describe (2-3 sentences) what happens to water following the apoplastic pathway when it encounters the Casparian strip.
Cell walls of the endodermis contain a waxlike, hydrophobic suberin that prevents apoplastic flow - water must pass through the plasma membrane and enter the symplastic pathway. Once past the Casparian Strip, water can again enter the apoplast and eventually reach the xylem.
The following crops have a determinate growth habit:
Corn and Wheat
Plant species that flower independently of photoperiodic condition are known as:
DNPs
Briefly (in 1-2 sentences) describe what a determinate crop is and list two example crops.
Determinate crops bear all at once and top off at a specific height.. its vegetative growth stops and flowering occurs over several days. Usually, apical meristems are converted to reproductive structures.. Ex; sunflower, maize, cereal crops.
WUE is the ratio of -- to -- and it is negatively affected by --
Dry matter or Yield water used by crop vapor pressure deficit
Hydraulic Redistribution is a passive process that moves water from wet to dry soils and can decrease nutrient availability.
False
Maintaining a weed-free environment during early crop growth (the first 4-6 weeks) is the only way to ensure maximum yield.
False
Describe (2-3 sentences) the process of hydraulic redistribution.
Hydraulic redistribution is the passive movement of water from the wetter soil the dry soil; in the vascular plants which have both their taproots deep to the water table whereas lateral roots near the surface. There are xylem pathways extending from taproot to lateral such that absence or abundance of water in laterals creates a pressure potential which is analogous to the transpirational pull. Thus in drought condition, water is pulled up via taproot to lateral and release in dry soils to replenish the water content whereas in flood condition , the opposite happens.
Movement in the phloem:
Is acropetal and basipetal
which of the following researchers is credited by some to have discovered oxygen
Joseph Priestly
What process does the Kautsky curve describe? Describe two major points or sections on the Kautsky curve.
Kautsky curve is a methods or techniques to determine the fluorescence induction (change in fluorescence yield) when light is switched on after a dark period. In plants when the light is switched on, the fluorescence yield first increases at a very fast pace and then decreases. In photosystem II, Chlorophyll A in plants emits fluorescence when it extracts electrons from water and put those electrons into the electron transport chain (which connects two photosystems). When light is switched on, electron acceptor reduces in photosystem II there by increasing the fluorescence yield. The two essential points on the curve are; the saturating pulse and maximum fluorescence in the light (F'm) is measured and when the actinic light is turned off and base level of fluorescence is measured (F'o)
Define and describe LAI (be sure to include units).
Leaf Area Index (LAI) is the ratio of leaf area (one side only) of the crop to the ground area (cm2 leaf area / cm2 land area = unitless) The interception of almost all radiation (>95% light interception) generally occurs at LAI > 3.0 - 4.0.. It further increases in LAI above 3.0 - 4.0 but often do not result in increased CGR. LAI is useful for understanding canopy function. Many of the biosphere-atmosphere exchanges of mass and energy occur at leaf surface. LAI is a unitless quantity because units of leaf area and units of ground area cancel each other.
Carbon isotope ratios (13C/12C) for C3 plants are:
Lower than for C4 plants (depleted)
Which of the following is the most common form of nitrogen transported in xylem and the preferred form for plant N uptake?
NO3-
As leaf area index increases above about 4.0
None of these answers are correct Canopy transpiration decreases, Canopy photosynthesis increases, Crop growth rate increases, Canopy light interception increases
The negative water potential in the xylem of a plant is a function of:
Only b and d are correct Transpiration, Negative tension in the water column
Describe (in 1-2 sentences) phytochrome and what it controls in plants.
Phytochrome are photoreceptors found in plants, microorganisms, etc.. where they help plants in knowing the light environment, in order to modify it's cellular process to fit in to the environmental changes. It role in plant development is to regulate plant growth by regulating gene expression, seed germination, stem elongation, leaf expression and flowering. It is found on almost all plant organs.
the form of phytochrome that absorbes red light is
Pr
Briefly (in 1-2 sentences) describe R/FR and what environmental information it provides to plants.
R/FR is the ratio of red to far red light, it is used to determine light quality - i.e. day vs. night or sun vs. shade
Describe (1-2 sentences) the process of remobilization in plants. Why does it occur?
Remobilization is the movement of compounds (nutrients, carbohydrates, proteins, etc.),from an area in the plant where they were previously deposited to an area where they can be re-utilized. This occurs because of an 'altruistic death' that allows for the degradation of the nutrients that are produced during the growth phase of the leaf and their redistribution to developing seeds or other parts of the plant, and thus is a strategy that has evolved to maximize the fitness of the plant
Define a trichoblast (1-2 sentences).
Root hairs are single cells that originate from a special type of epidermal cell capable of forming a root hair known as trichoblasts, in which their fate can be determined by asymmetrical division or by positional effects.
Define (in 1-2 sentences) senescence.
Senescence is the ordered degradation of cellular contents and results in the remobilization of nutrients via the phloem. (represents a normal part of the plant developmental process rather than a response to stress. ex; color change, leaf fall, root shoot)
Dark reactions of photosynthesis occur in this part of the chloroplast:
Stroma
Describe (1 sentence each) two of the primary pathways for water uptake by roots (i.e. transport from roots to xylem).
Symplast - through plasmodesmata Apoplast - through cell walls and intermembrane spaces Transmembrane - through plasma membranes
Briefly describe (1-2 sentences) what the light compensation point is in a light response curve.
The light compensation point is the light intensity on the light curve where the rate of photosynthesis exactly matches the rate of cellular respiration. When the rate of photosynthesis equals the rate of respiration or photorespiration, the compensation point occurs. The compensation point is reached during early mornings and late evenings.
Name three compounds that can be transported in phloem.
The major function of phloem is to transport photosynthesis products to their site of synthesis, these being; carbohydrates, amino acids, and minerals.
Briefly describe why LAI values over 4.0 (i.e. 100% light interception) are not typically beneficial to the crop.
This is not typically beneficial to the crop because it is less efficient for the crop. It is adding extra biomass with out getting any extra photosynthesis and harvest. Essentially it is energy that is moving toward growth, that does not need to occur.
light reactions occur in this part of the chloroplast
Thylakoid membrane
Briefly describe (in 1-2 sentences) two reasons why thylakoid membranes are important.
Thylakoid membranes contain the proteins in lipid bio layers which play an important role in light-harvesting and the light-dependent reactions of photosynthesis. There are four major protein complexes in the thylakoid membrane: Photosystems I and II.
Solar Radiation travels through space in the form(s) of
Waves and particles
To calculate CGR or SGR, the following part(s) of the plant growth curve should be used:
a and b are correct Exponential, Linear
the slope of the relationship between CGR and LAI can differ among crops because
a and c light conversion efficiencies vary, canopy architecture can differ
The slope of the relationship between CGR and LAI can differ among crops because:
a and c are correct c. Canopy architecture can differ. a. Light conversion efficiencies vary
a. Using the correct part of the curve, the aboveground biomass at 50 days was 50g/m2 and at 100 days was 100 g/m2. What is the CGR (include units)? b. Using the correct part of the seed growth curve, seed biomass at 60 days was 10 g/m2 and at 90 days was 40 g/m2. What is the SGR (include units)? c. Calculate the Partitioning Coefficient.
a. (100-50 g/m2)/ (100-50) = 1 gm-2 d-1 b. (40-10 g/m2 / (90-60) = 1 gm-2 d-1 C. 1/1= 1
The negative impacts of non-living factors on plants is known as --- , while the negative impacts of other living creatures on plants is known as ---
abiotic stress biotic stress
In the summer (July), DLI is
about equal in Florida and Maine
Name three things that can happen to light energy (solar radiation) after striking a leaf.
absorbed, reflected, transmitted After striking a leaf, light energy will be absorbed by the chlorophyll pigments, which take specific wavelengths from sunlight (mainly red and blue). Electrons absorb the energy from light and "boost" electrons to a higher energy level. Any light that does not have enough energy or too much energy can not be absorb and the energy is lost (fluorescence inefficiency) The LHC functions as a receptor and help deliver the energy captured by pigments to the center of a photosystem.. (P700 and P680).. they convert photons that is light into chemical energy, then chemical energy sugar is produced in the dark reactions
Fv/Fm is
all answers are correct relatively insensitive to mild stress, reported in many studies that measure fluorescence, relatively easily measured
Fv is
all answers are correct the difference between Fo and Fm, occurs once a saturating pulse of light is given to a dark adapted leaf, variable fluorescence
The following characteristics determine the amount of solar radiation received at the earth's surface
all choices are correct latitude, day length, sun angle
Plant growth is a function of:
all of the above b. Environment, Genotype, d. phene performance, c. the interaction between genotype and environment
The following methods could be used to measure the water status of individual plants:
all of the answers are correct IRGA, Xylem sap flow, Pressure bomb, RWC
sieve elements
all of the answers are correct (quiz 5)
leaves begin to export more assimilate than they import when they
attain about 50% of full size
If a plant enhances water uptake and reduces water loss under water deficit, it is exhibiting drought avoidance .
avoidance
Mycorrhizae
b and e are correct b. Are fungi, e. Greatly increase the surface area of roots
Isotopes are -- forms of the same element that differ in their number of ---
both radioactive and nonradioactive neutrons
Transpiration depends on:
c divided by b c. the sum of the stomatal and boundary layer resistances/ b. the difference in the water vapor concentration in the leaf and the air
Senesence is:
energy dependent developmental process
If a plant takes a shorter time to complete it's life cycle or to reach reproductive maturity under water deficit, it is exhibiting drought --- .
escape
As the wavelength of light increases, its frequency and energy:
frequency decreases, energy decreases
When choosing a leaf for an OJIP measurement, the leaf should be____________
healthy (non-diseased)
Briefly describe the light reactions of photosynthesis. Describe the following in your answer: i) What flows through the z-scheme,ii) What is the purpose of the light reactions,iii) What are the inputs and ultimate products of the light reactions,iv) Where in the cell do these reactions occur, andv) How do the light reactions differ in C3 and C4 plants?
i) It is a photochemical energetic pathway (so electrons) iii) inputs are CO2+2H2O+(hv) and ultimate products are NADPH and ATP iv) in photosynthesis, the light-dependent reactions take place in the thylakoid membranes v)
Which one of the processes listed below is one of the primary phases involved in root hair development?
initiation
Movement in the phloem
is acropetal and basipetal
Tropospheric ozone is
is considered a pollutant
Name a leader in plant/crop physiology and summarize their contribution in 2-3 sentences.
lecture 1
light compensation point is the
light intensity at which net photosynthesis is zero
Inside a dense corn canopy, the ratio of R/FR would be:
lower than at the top of the canopy
inside a dense corn canopy, the ratio of R/FR would be
lower than at the top of the canopy
As standards of living increase, the people of developing countries tend to increase the percentage of ---- in their diets
meat
as leaf area index increases above 4.0
none of these answers are correct ( quiz 5)
Edaphic factors include:
only b and c are correct b. Soil moisture, c. Soil pH
Root hairs are:
only two answers are correct
the deposition of assimilate into various plant parts is referred to as
partitioning
WUE is defined as the ratio of --- to ----and is generally higher in -- plants.
photosynthesis transpiration C4
which of the following is an example of a horticultural crop
potato
The most water deficit sensitive stages of growth are stages involving --- cell expansion and the --- water requirements.
rapid maximum
The hypersensitive response in plants can involve -- and---
rapid cell death sequestration of the pathogen
Two factors that can affect nitrogen fixation in crops include ---and---
soil nitrogen content inoculant source
which region has the highest prevalence of undernourished people
sub-sahara africa
the most common assimilate compound transported in the phloem is
sucrose
SAR is --- and involves ---
systemic acquired resistance increased pathogen resistance
Environmental factors that impact reference ET include --- and --- , among other factors.
temperature VPD
PSII...
two answers are correct
Root hairs are:
two of the answers are correct
Coping strategies plants have for mineral stress include --- and---
vacuolar sequestration of ions exclusion of salt
Solar radiation travels through space in the form(s) of
waves and particles
CER can be a negative value
when irradiance is zero and respiration is occurring
cells that are involved in phloem loading and located adjacent to phloem cells are known as
xylem cells
Identify three environmental of physical factors that can affect single leaf photosynthesis
• Light • CO2 • Temperature • Water • Nutrients • Leaf Age Factors that can affect single leaf photosynthesis are; wind turbulence (affecting rb), temperature/ climate, and light intensity.
Describe (in 1-2 sentences) what measurements the IRGA can make that quantify the water status of a leaf.
• Stomatal conductance • Photosynthesis • Transpiration An IRGA closed system can show that CO2 concentration in chamber decreases and water vapor increases. In turn, the rate of CO2 depletion is photosynthesis and we can quantify the water status of a leaf via the rate of water vapor increase by transpiration.
