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Plant Science
Question | Answer |
---|---|
Physiology refers to what? | The process and activities with the functioning of a living organism. |
What are two items that decrease photosynthesis? | Water and Nitrogen |
Does photosynthetic rate of individual leaves increase or decrease with age? | Decrease |
Young leaves actively capture sunlight with a peak at about how many weeks of age? | 3 |
When do young leaves become inactive? | 4-8 weeks |
Should you graze or cut old, non-productive leaves? | Yes |
Do leaves age more rapidly under warm or cool conditions? | Warm |
What is growth rate of a pasture related to? | The total photosynthesis of the stand |
Initially, do all leaves contribute to plant growth? | Yes |
As leaf number increases, what happens? | Shading of lower leaves increases |
As leaf mortality increases, what decreases? | Net accumulation of green matter |
What are the effects of shading? | 1. Reduced photosynthesis 2. Increased leave length 3. Reduced leaf width and thickness 4. Bud and grass tiller development and branching of legumes decreases 5. Internode length and plant height increase 6. Legumes show reduced nodulation and N fix |
What does the arrangement of leaves affect? | The amount of light intercepted and the photosynthetic potential of the sward |
What is a sward? | Grass-covered soil |
Which type of leaf display allows the greatest amount of light absorption? | Horizontally displayed |
What is an example of a plant that has horizontally displayed leaves? | Tall fescue |
How is self-shading of horizontal leaves prevented? | By grazing the plant |
Based on temperature, what are the three groups of warm season perennial grasses? | Intolerant to cold (Tifton 85) Relatively cold-hardy (Coastal) Cold Hardy (Switchgrass) |
What is the major limiting factor of plant growth? | Water |
Where is water transpired? | Through leaves |
What does water carry throughout the plant? | minerals, sugars, amino acids |
What is the most limiting nutritive factor? | Digestible energy |
What are some factors affecting forage quality? | Species, climate, rain, humidity |
What is the greatest effect on forage quality? | Maturity |
What will consumption of toxic substances or mineral imbalances result in? | Reduced productivity, being ill, death |
Fescue toxicity is a problem in what type of fescue? | Pure stands |
What is fescue toxicity? | Vasoconstriction of extremities resulting in loss of hooves, ears, tails, etc. |
What clovers can cause bloat? | Button, White, Persian |
What causes Nitrate poisoning? | Consumption of pasture or hay containing high levels of Nitrate |
Does danger of Nitrate poisoning decrease with time? | NO |
Is hay containing 2500 PPM Nitrate usually safe? | Yes |
What are some plants known to have Prussic Acid problems? | Johnsongrass, Sorghum, Sudangrass, Wild Cherry |
Which plant does NOT produce prussic acid? | Pearl Millet |
What can cause prussic acid build up? | Frost, drought, herbicides, stress in general |
How long can the fungus that causes Bermudagrass Staggers stay toxic? | Up to two years |
What is a young plant in a resting state? | A seed |
What are the components of a grassland ecosystem? | Non-living (water, air, soil), Plants, Herbivores, Decomposers (earthworms, fungi, bacteria) |
Pasture yield potential increases as leaf area increases until leaves intercept how much light? | 90% |
What should the objective of a grazing method be? | To manage the pasture and other feed inputs to efficiently produce animal products |