Transcript Lesson 2
CRSS 2830 Lesson 2 Growth and Development of the Turfgrass Plant BOTANICAL CLASSIFICATION OF TURFGRASSES Angiosperms (flowering plants) • Dicotyledons (dicots) – broadleaf plants • Monocotyledons (monocots) – grasslike plants MONOCOTYLEDONS • Family= Poaceae (Gramineae) – Kentucky Bluegrass ‘Merion’ – Genus = Poa (bluegrass) could also be: annual bluegrass, rough bluegrass, Canada bluegrass, etc. – Species = pratensis (Kentucky Bluegrass) • Cultivar = Merion MONOCOTS VS. DICOTS • Monocots: – Single seed leaf – Parallel leaf veins – Growing point soil level – Fibrous root system MONOCOTS VS. DICOTS • Dicots: – Two seed leaves – Branched leaf veins – Growing point at top of stem – Often tap root system TURFGRASS PLANT STRUCTURE • Roots: – Stems: • Crown = growing point (new leaves, roots, stems) • 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: – St. Augustinegrass – Centipedegrass – Creeping bentgrass – Buffalograss – Rough bluegrass EXAMPLES • Rhizomatous turfgrasses: – Kentucky bluegrass – Creeping red fescue – bahiagrass EXAMPLES • Turfgrasses with both rhizomes and stolons – Bermudagrass – Zoysiagrass EXAMPLES • Turfgrasses without rhizomes or stolons (bunch-type): – Tall fescue – Perennial ryegrass – Annual ryegrass ORGANS OF TURFGRASS PLANTS LEAVES TILLER RHIZOME CROWN SHOOT ROOTS STOLON TURFGRASS GROWTH • Shoot – 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). CARBOHYDRATES AND GROWTH • Photosynthesis = production of carbohydrates from CO2, water, and sunlight (releases oxygen) • Respiration = breakdown of carbohydrates using oxygen. Releases CO2 and energy. CARBOHYDRATES & GROWTH • Energy 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. CARBOHYDRATES & GROWTH • Plants 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.