CRSS 2830 Lesson 2 Growth and Development of the Turfgrass Plant

BOTANICAL CLASSIFICATION OF TURFGRASSES BOTANICAL CLASSIFICATION OF TURFGRASSES Angiosperms (flowering plants) Dicotyledons (dicots)Dicotyledons (dicots) –broadleaf plants Monocotyledons (monocots) Monocotyledons (monocots) – grasslike plants

MONOCOTYLEDONS Family= Poaceae (Gramineae)Family= Poaceae (Gramineae) –Kentucky Bluegrass ‘Merion’ –Genus = Poa (bluegrass) could also be: annual bluegrass, rough bluegrass, Canada bluegrass, etc. –Species = pratensis (Kentucky Bluegrass) Cultivar = MerionCultivar = Merion

MONOCOTS VS. DICOTS MONOCOTS VS. DICOTS Monocots:Monocots: –Single seed leaf –Parallel leaf veins –Growing point soil level –Fibrous root system

MONOCOTS VS. DICOTS Dicots:Dicots: –Two seed leaves –Branched leaf veins –Growing point at top of stem –Often tap root system

TURFGRASS PLANT STRUCTURE Roots:Roots: –Stems: Crown = growing point (new leaves, roots, stems)Crown = growing point (new leaves, roots, stems) Flowering culm (inflorensence seedhead). Usually not desirable in turfgrass areas.Flowering culm (inflorensence seedhead). Usually not desirable in turfgrass areas.

Lateral stems –Primary = tillers (vertical, upright) –Secondary = »Rhizomes = below ground »Stolons = above ground * Rhizomes and stolons have horizontal or spreading growth habit. Sod forming grasses.

EXAMPLES Stoloniferous turfgrasses:Stoloniferous turfgrasses: –St. Augustinegrass –Centipedegrass –Creeping bentgrass –Buffalograss –Rough bluegrass

EXAMPLES Rhizomatous turfgrasses:Rhizomatous turfgrasses: –Kentucky bluegrass –Creeping red fescue –bahiagrass

EXAMPLES Turfgrasses with both rhizomes and stolonsTurfgrasses with both rhizomes and stolons –Bermudagrass –Zoysiagrass

EXAMPLES Turfgrasses without rhizomes or stolons (bunch-type):Turfgrasses without rhizomes or stolons (bunch-type): –Tall fescue –Perennial ryegrass –Annual ryegrass

RHIZOME TILLER STOLON ROOTS SHOOT LEAVES CROWN ORGANS OF TURFGRASS PLANTS

TURFGRASS GROWTH ShootShoot –stem and leaf (leaf = sheath and blade) Sheath is lower portion of leaf and is attached to the crown where leaf growth initiated. Sheath rolled or folded around each other and support leaf blades. When older leaf dies, new leaf develops with in the sheath of the next oldest leaf and emerges at the top of the plant. Besides the crown, there is the meristematic tissue at base of leaf blade (explains leaf extension).Sheath is lower portion of leaf and is attached to the crown where leaf growth initiated. Sheath rolled or folded around each other and support leaf blades. When older leaf dies, new leaf develops with in the sheath of the next oldest leaf and emerges at the top of the plant. Besides the crown, there is the meristematic tissue at base of leaf blade (explains leaf extension).

CARBOHYDRATES AND GROWTH Photosynthesis = production of carbohydrates from CO2, water, and sunlight (releases oxygen)Photosynthesis = production of carbohydrates from CO2, water, and sunlight (releases oxygen) Respiration = breakdown of carbohydrates using oxygen. Releases CO2 and energy.Respiration = breakdown of carbohydrates using oxygen. Releases CO2 and energy.

CARBOHYDRATES & GROWTH Energy released via theEnergy released via the breakdown of carbohydrates needed to build cells and tissue (drives enzymatic reactions). Photosynthesis must exceed respiration if the plant is to grow. Photosynthesis must exceed respiration if the plant is to grow.

CARBOHYDRATES & GROWTH Plants also store carbohydrates forPlants also store carbohydrates for later use. Carbohydrate accumulation greatest when photosynthesis high and plant growth slow.

CARBOHYDRATES & GROWTH During dormant states, respiration draws on stored carbohydrates to keep cells alive.During dormant states, respiration draws on stored carbohydrates to keep cells alive.