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Forages Exam 1
Terms in this set (14)
List 3 diff. terms that are used to name natural grasslands in the USA in other parts of the world. What are the most significant differences b/w these differently named grasslands.
Prairie- French in Canada; cool season grassland
Meadow- English settlers; native grassland suitable for mowing
Savannah- Spanish in FL- warm season grassland
differences in climates and species
What are some of the most significant diff. in the modern grasslands of the eastern U.S. versus the western U.S.?
Eastern: cool season in NE, warm season in SE
have to be managed
most grassland is fenced in
none native species fenced
Western: native warm season
do not have to be managed
not fenced/open grassland
What mgmt practices did the Native Americans use on the mid-continent grasslands of North America and how it has influenced modern grassland mgmt?
They would selectively burn large areas in order to contribute to the abundance of productive grasses by removing old ungrazed forage, recycling minerals, and reducing the amount of weeds and shrubs- this would entice bison.
This relationship developed the native grasslands that provided great wealth for all of those depending on the land. Once the herds were destroyed in the 1800s, Native Americans and the prairie were subdued.
Explain how proper canopy height mgmt can be crucial to both summer regrowth and winter survival in the mgmt of legumes.
Canopy should be mngd to maximize light interception over the course of the growing season
Defoliation reduces leaf area that must be regenerated for light interception
plants need active shoot apices and meristems for regeneration-
Describe the festucoid and panicoid types of seed germination and describe any advantages or disadvantages of each type.
Festucoid: most cool season grasses: the coleoptile elongates from near the seed to reach the soil surface
-easier to establish under sporadic rainfall due to coleoptilar node remaining at seeding depth (where water conditions are more favorable for root growth
Panicoid: most warm season grasses: the mesocotyl (b/w scutellar and colepotilar nodes) also elongates to push the coleoptilar node and the short coleoptile upward to the soil surface
-places roots close to the surface
- coleoptile protects the emerging shoot
-adventitious roots rarely grow in dry soil
Proteins and lipids are biologically expensive. Explain the truth of that previous statement
Respiratory costs for synthesis of new tissue depends on its composition; glucose is a building material. It takes more glucose to build proteins and lipids that it dose to build starch. Protein needs to take up and reduce NO3-.
Explain the differences in plant crown function in alfalfa and birdsfoot trefoil with respect to winter survival and regrowth following cutting or grazing.
alfalfa stores photosynthate in roots (after a certain point), this continues until full bloom. The storse are used for seed development and new shoots are formed from the crown.
In grasses, storage occurs at the stem base. If overgrazed or cut too low, regrowth is slower.
Birdsfoot trefoil can be cut many times but not closely. It stores carbs over winter to support spring growth, but they aren't restored lin roots @ flowering (like in alfalfa).
Deeper crowns allow soil to provide cold protection of axillary buds needed for spring regrowth
Define Leaf Area Index and discuss its relationship to forage harvest mgmt.
Comparison of how many square centimeters per square cm of soil surface those leaves are covering (this is dependent on plant species)
Use it to help mng how we keep our canopy
95% light interception is desired (harvest now for max productivity)- after, old leaves die
LAI is dependent upon leaf angle, whether or not the plant grows horizontally vs vertically, leaflet size and shape
Describe and explain the fxnal and structural differences b/w C3 and C4 plants. How do the anatomical differences influence the nutritional value of the plants?
Only mesophyll cells of C3 plants have well-developed chloroplasts
C3 plants form carbs by adding CO2 to RuBP (sugar) thru the activity of rubisco (enzume). This forms a highly unstable 6 C compound that immediately forms 2 molecules of a 3-carbon product (hence C3). These molecules move from chloroplast to the cytosol to be combined into glucose. one glucose molecule is converted to fructose and combined w/ another glucose to form sucrose for transport thru the phloem. when photosynthesis exceeds transport capacity, the 3 carbon sugars in chloroplast are used to form starch in the stroma.
O2 reacts w/ rubisco and reduces the amount of CO2- with no benefit to the plant and reducing photosynthesis.
C4 plants have chloroplasts in both mesophyll and bundle sheath cells (more efficient).
Nearly all the rubisco in C4 plants is found in bundle sheath chloroplasts but CO2 is captured in mesophyll cells by PEP carboxylase. PEP carboxylase adds CO2 to the 3 carbon PEP to form 4 carbon organic acids (hence c4). These acids are transported from mesophyll cells to bundle sheath cells where CO2 is released reacts w/ rubisco in the same manner for C3 plants. The PEP recycles back to mesophyll cells to start over. This process increases the CO2 concentration in the bundle sheath cells. photorespiration is eliminated in this process.
Explain how photoperiodism and vernalization affect the reproduction of forage species.
Photoperiodism: Regulation of plant response by the duration of daylight
Vernalization: A cold treatment required by shoot apices of certain species in order for them to properly flower
Floral induction must occur under (species) specific circumstances involving photoperiodism and vernalization...The plant's photoperiodism and vernalization requirements must be met in order for reproduction to occur.
What is the single most important reason to understand the structure and morphology of forage legumes and grasses?
Understanding the morphology of forage legumes and grasses enables one to identify the types of plants growing in their fields, allowing for proper treatment of these plants for forage use.
Differentiate Growth Respiration and Maintenance respiration
Respiration itself is only one process, but may be classified into growth and maintenance respiration.
Growth- used for synthesis of new tissues
Maintenance- used to repair and ensure the proper functioning of mature, nongrowing tissues
Mixed stand forages often present somewhat of a problem in deciding when to harvest them. Using the example of alfalfa and timothy grown as a mixed stand, explain the consequences of cutting at the proper time for alfalfa versus the right time for timothy.
For good quality hay, alfalfa ought to be cut b/w bloom and seed maturity (to use it as a forage feed)- 10% bloom (1 stem in 10 is starting to flower)
Leaves are starting to get old but you also lose food storage due to the alfalfa producing seeds and new stems for seed production
At this point, timothy has low stem base carb levels and it may not recover. it has few tillers to help the plant recover.
What are the diff in carb storage form in warm season grasses, legumes, and cool season grasses? What, if any, are the fxnal implications of these differences??
Legumes: store starch in roots, rhizomes, and stolons
C4: aslo accumulate starch
C3: accumulate fructan (polymer of fructose) in their vegetative tissues
Starch is insoluble and stored in amyloplasts in legumes and warm seasons
Fructan is soluble and stored in vacuole (enzymes for fructan metabolism operate at lower temps)- better adaptation for C3
They all store starches in chloroplasts and seeds
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