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Dec 30, 2015
TYPES OF STEMS1. Crown-highly compressed stem2. Tillers-primary lateral stem3. Stolons-above ground, secondary lateral stem 4. Rhizomes-below ground, secondary lateral stem5. Culm -stem of grass plant, flowering
Basic Plant Structure
Basic Plant Structureapicalmeristem
Basic Plant StructureapicalmeristemLeaf Blade (lamina)Petiole
Basic Plant Structureapicalmeristemnode
Leaf Blade (lamina)
Basic Plant StructureapicalmeristeminternodenodeLeaf Blade (lamina)
Basic Plant Structureapicalmeristeminternodenodeaxillary bud
Leaf Blade (lamina)
Basic Plant Structureapicalmeristeminternodenodeaxillary budprimaryrootsecondary, branch rootLeaf Blade (lamina)
Basic structure, compressed
The Grass Plant
The Grass Plant
TillersDevelop from axillary budsUsually live less than 1 yearSome produced in spring, important for summer survivalSome produced in fall, usually die late spring, early summerEnhanced by mowingSome grasses only produce tillers - Bunch grassesTillers represent the future for bunch grassesIntravaginal shoot development
StolonsGrow along soil surface, abovegroundLive one or more yearsProduced in fall for cool season grassesIn spring for warm season grassesExtravaginal shoot development, involving rupture of surrounding sheath tissueStolons may branch profuselyThese grasses are sod-forming
RhizomesGrow underneath the soil, an underground version of the stolonDeterminate (KBG) are short and non-branchingIndeterminate (Berm.) are long and multi-branched.Provides sod strengthWinter survivalWear toleranceMajor storage organ for long-term survival
The CrownMost important part of plantPlace where new shoots developHighly compressed series of nodesWhere all the leaves are attachedWhere all the axillary buds are locatedWhere tillers, rhizomes, stolons originateHighly protected!
The Phytomer UnitThe smallest complete unit containing all the necessary parts of the turf plant:Node Internode (stem piece)Axillary bud at nodeRoot Primordia at node
A phytomer can survive on its own - this is the basis for vegetative propagation.
CULM - The Flowering ShootPhases:a. Maturation - plant must be old enough, big enoughb. induction1. Vernalization - cold treatment - take place in growing point - reversible. Cool season grasses2. Photoperiod - takes place in leaves cool season = long day warm season = short dayc. Initiation - crown changes from vegetative to flowering - elongation occursd. Development - seed head formation
CULMDisadvantages:b. drains food reservesc. death of shootd. mowing is difficulte. affects play, Poa annuaa. unsightly
II. LEAVESThe leaves are the major site of food production. They contain the green pigment chlorophyll. Photosynthesis is the process that produces carbohydrates. Leaves originate at the crown, both the apical meristem and axillary buds.
What is a meristem?Intercalary meristem?
II. LEAVES (continued)1. Componentsa. bladeb. sheathc. collard. ligulee. auricle2. Vernation 3. Leaf #/shoota. same for given environ, usually 5-10/shoot
RootsIf you can grow roots, the shoots will take care of themselvesAnchorageAbsorption of water and nutrientsStoragePrimary, or seminal develop from seed, short livedAdventitious roots develop later and then continuously from the nodes. Nodal roots.
Regions of the RootRoot CapMeristemRegion of ElongationRegion of Differentiation - where root hairs develop, and also vascular tissueRegion of Maturation, where suberization occurs. Roots become more rigid. Lateral roots form
Root SystemsMultibranching and fibrousTurf roots not major storage organsSource of plant hormones, cytokininsUsually 4-18 inches deepWarm-season grasses have larger diameter, deeper roots than cool-season grasses
Root HairsSteleRoot CapMeristemElongationDifferentiationMaturation
Restrictions to RootingHigh soil temperaturesAcidic soils, aluminum toxicityLack of oxygenSaltsPesticidesImproper mowing height, frequencyExcessive N, deficient K nutritionExcessive thatchImproper irrigationFlowering
Root LongevityDeath and replacement is continuousSome roots last < 6 months, some > 2 years (KBG)Seasonal root growth: cool-season best in spring and fall, warm-season best in summer. Spring root decline in WS, summer root decline in CS.
Temperature Effects4. Cool Seasona. Growth Curveb. Temperature:Min - 33oF Opt - 50-65oF Max - 80oF5. Warm Seasona. Growth Curveb. TemperatureMin - 40oF Opt - 75-85oFMax - 110oF
WARM SEASON GRASSESCOMMON BahiaBarnyard GrassBermudaCentipedeDallisgrassGoosegrassJapanese Lawngrass (Zoysia)Large CrabgrassSmooth CrabgrassSt. AugustineYellow FoxtailSCIENTIFIC(Paspalum notatum)(Echinochloa crusgalli)(Cynodon dactylon)(Eremochloa ophiuroides)(Paspalum dilatatum)(Eleusine indica)(Zoysia japonica)(Digitaria sanguinalis)(Digitaria ischaemum)(Stenotaphrum secundatum)(Setaria glauca)
COOL SEASON GRASSESCOMMONAnnual BluegrassKentucky BluegrassRough BluegrassColonial BentgrassCreeping BentgrassItalian RyegrassOrchardgrassPerennial RyegrassQuackgrassRed FescueTall FescueSCIENTIFIC(Poa annua)(Poa pratensis)(Poa trivialis)(Agrostis tenuis)(Agrostis palustris)(Lolium multiflorum)(Dactylis glomerata)(Lolium perenne)(Agropyron repens)(Festuca rubra var. rubra)(Festuca arundinacea)
General Growth CurvesJan. Mar May July Sept Nov. GrowthWarm SeasonCool Season
Regions of Adaptation
Regions of AdaptationCool HumidWarm AridWarm HumidTropicalTransitionCool HumidCool Arid
PHYSIOLOGY1. Two processes required for growth:
a. photosynthesisb. RespirationGrowth = photosynthesis - respiration
PHYSIOLOGY Photosynthesismanufactures foodH2O + CO2 + light = sugar + O2 + water Sugars used to build new tissue, and to maintain existing tissue through respiration.Sugars stored in crowns, stolons, rhizomes and roots.
PhotosynthesisCool season grasses, C3, 60 - 75oWarm Season grasses, C4, 80 - 95oC4 plants can utilize high light better
C3 vs. C4 Species Light IntensityPhotosynthesisC3 speciesC4 species
RespirationProduces energy to build tissue, maintain existing tissuesCarbohydrates broken down sugar + O2 = CO2 + H2O + energy
PHYSIOLOGYWarm season - respire mainly in darkCool season - respire in dark and light. This is called "photorespirationComparisonPhotorespiration Photosynthetic rate rate
C3 High LowC4 Low High
Environmental EffectsPhotosynthesis slightly affected by temperature.Respiration affected greatly by temperature. As temperature increases, so does respiration.Accumulate food in cool temperaturesPhotosynthesis > respiration Deplete food in high temperaturesRespiration > photosynthesis EX: Summer fertilization of cool season grasses
PHYSIOLOGYAccumulate food when growth is slow. eg. Fall fertilizationDeplete food when growth is fasteg. spring root die back eg. Recovery from environment or pesteg. Seed head production