GRAS 2614: Grassland Science & Wildlife Ecology

• This module is called GRAS 2614, titled "Grassland Science," focusing on Grassland and Wildlife Ecology as a Natural Resource
• The course is presented to both B.Agric and B.Sc.Agric students in their second year
• This module is 16 teaching credits and is presented during the first semester, with an examination in June
• Students learn about Grassland Science and Wildlife Management, including veld vegetation ecology and herbivore game species
• Students are trained to identify plants and herbivore game species
• Module requires 160 notional learning hours

Key Dates

• The module spans 15 weeks, with 3 hours of theory and 3 hours of practical work per week
• Theory classes are held on Tuesdays and Thursdays 12:10-13:00 (LG4)
• Practical classes are held on Wednesdays 13:10-14:00 (EDU AUDITORIUM) and Wednesdays 15:10-17:00 (W202/WEST CAMPUS)
• Attending 80% of theory classes is compulsory, failure leads to an incomplete for the module
• 100% practical attendance is required to obtain a semester mark for the module

Course Content

• The course covers vegetation and wildlife species in South Africa, pasture ecology, pasture plant growth, and pasture utilization
• South African pasture plants, indicator and problem plants, the game industry, and wildlife production principles are covered
• Explores herbivore game species, their habitat needs, diet selection, ecotourism, venison, legislation, and management principles

Module Assessment

• Theory and practical sections contribute 50% each to the semester mark
• Assessments must be completed to write the examination
• A medical certificate is required for missed assessments to be completed later
• Test 1 (Written) contributes 22% to final mark
• Test 2 (Written) contributes 22% to final mark
• Class activities/quizzes (Written) contribute 6% to final mark
• Practical assessments (Written) contribute 10% to final mark
• Practical tests (Written) contribute 40% to final mark
• No promotion system applies; late submissions are not accepted; all assessments are compulsory
• The final mark is calculated by 50% of the module mark plus 50% of the examination mark to pass, a student needs 50% or more

Grassland Science

Chapter 1: Pasture Plants

• Phenological development includes aboveground (leaf, shoot, seed, flower) and underground (root) growth, starting with vegetative (leaves, shoots, roots) and then reproductive growth (seeds, flowers)
• Grass development occurs from seeds or tillering from the parent plant

1.1 Vegetative growth

• Germination occurs when dormant seeds develop into seedlings under optimal water, oxygen, temperature, and sunlight
• Imbibition is the initial step of seed germination: absorbs water, activates enzymes, begins metabolic processes, softens and swells: initiating biochemical processes such as enzyme activation and breakdown of food resources
• Activation occurs once the seed absorbs enough water. Its metabolic processes activate, breaking down nutrients in the endosperm
• Radicle (embryonic root) emergence is the first visible sign of germination. The internal pressure (imbibitional pressure) in seed cracks/softens the seed coat
• Radicle helps in the root system by anchoring the plant and providing water and nutrient absorption
• Coleoptile (shoot) emergence: As radicle grows, the seedling grows:
  • Coleoptile: protective sheath that holds developing shoot
  • Mesocotyl: Connective tissue pushes coleoptile upward, allowing emergence, and stores + transfers nutrients

1.1.1 Emergence & leaf formation

• First leaf emergence occurs once the coleoptile reaches the surface, helps the seedling begin to photosynthesize, converting sunlight into energy
• Leaf formation occurs once initial leaf emerges and additional leaves develop from the unelongated "stem" / growing point at the base of plant (the meristematic zone: cell division, elongation and differentiation occurs)
• Apical meristem accounts for stem/shoot growth, and the intercalary meristem produces leaf primordia

Grass structure

• The promeristem with the youngest cells form different primary meristems, where tissues for grass shoot develop
• Forming young leaves on either sides of the growing point leads to folds (primordia)
  • 2 parts: leaf sheath (attaches to the grass shoot) and leaf blade (lamina). Joined by the collar connective tissue
• Parenchyma cell layer divides cell layer into two. Top cell layer grows the lamina
• Meristematic parts are protected by sheath + laminae for the young lamina. Meristematic activity stops after the ligule has differentiated
• Leaf sheath continues to elongate until the ligule is exposed
• Defoliated leaf blade may continue, Intercalary meristem removal prevents leaf blade renewa
• Grasses are able to withstand defoliation: cell formation and cell elongation are too protected by the plant
• New leaves develop from growing point (lower) during the vegetative growing period Lowest point = oldest/ youngest part (base)

Rate of leaf formation

• Rate of leaf primordia & rate at which the lamina appears measure leaf growth
• The leaf primordia isn't = lamina. Primordia > Leaves
  • Formation is linked to flower formatio
• Two factors influencing rate of LF = temperature & light
  • Temperate grasses peak LF rate: 18°C - 29°C
  • Tropical grasses peak LF rate: 29°C - 33°C
• Ensuring proper crop temperatures is V important
• Light intensity / photoperiod can seasonally fluctuate LF rate

Factors influencing leaf formation

• Leaf area or leaf size: influenced by temperature, light, and minerals
  • Leaf area increases with moderate temp (20-25°C), decreases after
  • Shorter and broader leaves grow in cool climates and narrower longer ones grow in hot climates
• Low light increases leaf size, decreases thickness. Specific leaf area sensitive to light intensity
• Nitrogen causes leaf area to drastically increase
• Leaf Age is low in grasses. Die-back can be synced with leaf maturity. Older leaves' meta activity decreases, cell products are redistributed. Most important factor? Damage
• New shoots form from small basal leaf bud (crown). Forms leaf primordia, shoot elongates. Tip apical meristem continuously produces new cells
  • Apical cells elongate to internodes (shoot growths)

Plant types

• Grass measured by shoots.
  • Maize is singular ~ 90 days
  • Forage grasses/cereals = 15 months. They flower & die w/o replacement shoots
• Perennials will sometimes form secondary shoots to replace originals for endurance
• Secondary Shoot Growth = from developing axils of primary growth shoots
  • New growth is leaf primordia w apical + bud. Vascular secondary bundle shoots are still bound to primary
  • Themeda triandra show intravaginal branching
  • Extravaginal branching: horizontal shoots form stolons close to the soil = defoliation resistance.
• Some flowering shoots may die within one year, some the next season. Non-flowering may spend anywhere between a few weeks and up to a year +

Factors influencing Shoot Formation

• Genetic differences cause shoot formation to be specific across grass species
• Temperature:
  • Temperate grasses optimum is between 18°C - 24°C , 24°C-29°C for rye [L. perenne] / Dactylis glomerata
  • Subtropical shoot growth increases even up to 35°C. Excess temperatures with high light intensity is detrimental
• Increasing light intensity, within reason, increases more shoot production
• Decrease in light = shoot + leaf decrease, length increase
• Water & Mineral Supply + shoot production Nitrogen, phosphorus and potassium fertilisations. Nitrogen is key. significant interaction is found with P and K.
• Themeda triandra 3:1 vegetative:reproductive ratio
• Eragrostis lehmanniana - 37:1 and Cymbopogon plurinodis-0.7:1
• Tuff occurs 18 months
• Meristem changes vegetative to reproductive. Secondary shoot formation + production of flower primordia takes place, stem elongates Point is lifted
• Secondary growing points for lateral shoots. Change from veg to rep represses lateral buds
• Developed flowe = lateral buds grow lateral and form shoots
• grazing vegetative, leaf production ceases, does not grow shoots. Stimulates lat shoot development
• Removing Reproductive apex lifts apical dominance for lateral stimulation

Reproductive Growth

• Grasses form both kinds of shoots, genetics
• Top Meristem changes from vegetative to reproductive
• Flower formation stages:
  • Apical meristem must initiate reproductive growth from vegetative growth, temperature / photoperiod dependent. Spring or other favorable conditions causes plants to shift from stem + leaf to flower.
    • photoperiod is primary stimulant Temperate grasses need low T to develop flower. Nature provides vernalisation temp. Effective temperatures between 0°C/10
• Quantitative vernalization increases treatment = earlier fruiting
• Minimum genera is two weeks, with Bromus inermis. Short light and temperature emulate the same.
• Leaves take photoperiod signal to the growing point Area to grow in photo period needs sensitive growing leaf

Spikelets & Florets

• Flowers start at apical meristem (leaves and stems)
• Changes to required structures Inflorescence, double ridges, axils is result. Development is fast for vegetive state. Spike, Branching and Species affect structure Individual spikelets are branches
• Spikelet Structure: contains bract flowers w pairs Glumes: base Lemma: covers floret Palea: covers developing floret Stamens: male, produces pollen Pistil: has ovary, style, stigma Spikelet weeks to grow depending on environment. Plant varies

Maturation (sexual reproduction)

• Grass flowering = reproductive maturation/development
  • Stamens + Pistils
  • Monoecious Grasses - both flower
  • Diecious Grasses seperate flowers
• Anther:
  • Formation is pollen in floret stamen
• Release:
  • Pollen is developed mature then winds carry pollen.

Anemophilou. Wind Pistil is mature - stigma & ovaries will seed.

• Pollination: Primarilly thru wind, self and cross occur
• Formation takes place when flower first open (after / before) - pushes lemma away - stigams + staman occurs. The period during the day can affect the spread of the seeds. (self pollination - dryness)
• Eggs, then seeds, result
• Zygotes will seed Harden, produce a seed. They have: Embryos in seed coating.
• Maturation with wind/ animals:
  • Coated with awns/ wings for wind
  • Hooks for animals enter dormancy until conditions are favorable Environmental+Genetic. Low moisture/high heat during anthesis is v bad. Climax grasses lighter than pioneers.

Root growth

• Parts need to be balanced
  • underground relies on above, vice versa)
• Plant + Pasture dependent Two root types
  • Primary roots exist, only long enough for secondary Roots can be from plant OR stolons OR nodes.
• Root system lifespan = 6/20. ( Trianda)

3 system classes

- superficial Roots system is annual
- DTR is trich and e. m
-DRS is dact, traindra, tetrachne and brachiara

• 1.2 Roots - fibruous and strong (crorcana in goosegrass)
• Up to 20m Roots cylinder cement slime. Has lehmanniana
• Except ORS system Buttness, or air. Stolons and Creeping Culm node system. Roots are node pressed.

Root Stocks and Stolons

• Root stocks - underground stems & buds
• Nodes w/ buds for shoots. (root stocks)
• UNDERGROUND
• Imper / Bromus / Pratensis grass types have underground system
• Cynodon has stolons. Llemfuesis too
• Secodnary - roots have much soil organic. Dense plants have a high amount - 60 cm

Seasonal Growth Factors

• When Plant can, system - all affected. Annual Roots : replaced YLY. Perinnials, have a rotation.

• Poa is YLY 58 %. The roots = shoot .limited and influeneced on plant type

• Carbs and ground. negative ratio between under/above. Autumn & Early Winter.

• low lvl with mosit increase secondary system - high temps hurt - water is key, and the roots adjust. Variation reflectes in the abount of area. Strategy is important

R and built ups are exclusive. Hard dough and sed are bad. 75 of the roots in the first peneteatre for 2-4

Shortages

Growth decreases.

Plant influence

1= degree 2 = plant age 3 = platm type. Young are more resistant than all together (young make up most)

• grasses resistance during vegetative Positive correlation as the tuft size. flowering and reproduction are the most important things.

less seed and vitality during hard times. V 39% or 75 of dry vs flood success.

The extent depends ont other conditions. Adaptation helps w/ resistance, adaptation is adapting the different layers & rooting in top layers Double = triandas highveld, is in top layer

excrete for the loose - absorbs is effectivly. sponge like for dry survival limited by system. elongation increase uptake, less competision. development ISNT high at times. Drought hurts growth. S growth, slow to restore