Week 2 Growth Flashcards
Outline three primary drivers of pasture growth.
Moisture
Temperature
Sunlight (least effect)
1st response to water stress
Cell expansion reduced = dec. water pressure/turgor pressure = dec. LAI = dec, Radiation captured
Soil Water affected by
OM Soil type Root Depth Evapotranspiration Rainfall Slope Aspect Soil structure, depth, texture, compaction
Explain the processes that a plant goes through during the regrowth phase.
After grazing
0-6 days Dec. PSN due to wounding effect
Root growth suspended
Dec. respiration
Recovery 6-12 days
Remobilisation of stored CHO, N
Primary allocation to shoots
Compensatory PSN
Ryegrass
Rainfall
Types
Positive
Negatives
Greater than 700mm
Highest quality is Italian
Italian has least persistance
Good production
Early/Late heading types - extends quality for longer
Diploid/tetraploid - Genetic Material is doubled = inc. ht, ice cell size, inc. digestible matter
Bigger = more qaulity = dec,. persistance
Endophytes - natural fungus
Good production
High Quality
Withstands contimual grazing
Low persistance in hot dry summers
Susceptable to insect attack
Phalaris
Rainfall
Types
Positive
Negatives
Greater than 500mm
Winter - semi dormant
Winter Erect
Acid tolerant varieties
Reduced alkaloid content = red. rate of staggers
High peristance
High produciton i winter/ spring
Lower qual to rye
Not good in acid soils
Low seedling vigor/self seeding poor
Staggers
Cocksfoots
Rainfall
Types
Pos
Neg
450mm
Mediterranean/hisponic
Temperate/continental
Intermediate
Acid Tolerant
Dec. animal health risks
Low seedling vigor
Lower quality to phalaris
Tall fescue
Types
Pos
Neg
Mediterranean
Temperate/continental types
Can include endophytes
Drought tolerant
Survives water l ogging
Tolerant of acid and alkaline soils
Between rye and phalaris in qual
Poor seedling vigor
Slow germ
Needs regular grazing
White Clover
Rainfall
Types
Pos
Neg
750mm Increased Stolon Freq = inc. presistence Increased LAI (Dairy)
Stolons = reprovuctive Tolerant of frequant hard grazing High feeding value Compliments grasses Persistent
High soil fert. required
Susceptable to drought
Not tolerant of lax grazing
Selectively grazed in pasture
Lucerne
Rainfall
Types
Pos
Neg
350-400mm
Highly winter active 10
Winter dormant 5
Most persistent legume due to 3 m roots
Drought tolerant
Cannot handle:
Set stocking, acidic soils, water logging
Sub CLover
has runners not stolon
Burrys seed in ground
Drought avoider not tolerant
Acid, neural and waterlogging tolerant types
Early/mid/late season cultivars
