TURFGRASSES A. J. Turgeon “Turfgrass management”, revised edition. Reston Publishing Company, Inc. A Prentice-Hall Company, Reston, Virginia, USA, 1985, pp C. Reed Funk and K. Morris “The evolution of turfgrass breeding has been like that of the grasses thenselves – adapting to change”, Grounds Maintenance, August 2000, P. Croce, A. De Luca, M. Falcinelli, F.S. Modestini, F. Veronesi “Tappeti erbosi – Cura, gestione e manutenzione delle aree verdi pubbliche e private”, Edagricole 2006, pp Turfgrass are plants that form a more or less contiguous ground cover that persists under regular mowing and traffic. An interconnecting community of turgrasses and the soil adhering to their roots and other below-ground organs forms a turf. The domestication and improvement of plant and animals was, and continues to be, essential for the progress and prosperity of civilization. This is true also for turfgrasses, as we grow turfgrasses in a wider range of soils, exposures, uses and management regimes than any other crop plant.

Turfgrasses are used to produce turfs for a variety of purposes: 1- Utility turfs exist primarly for soil stabilization, to prevent erosion from wind and water. Furthermore, the protective cover of aerial shoots provides a cooling effect during warm weather. Along roadsides, turfgrasses absorb toxic emissions showing a cleaning effect upon the air. Along airport runways, turfgrasses reduce dust to prolong engine life. 2- Lawn turfs serve decorative and psychological functions; the uniform, green appearance enhances the beauty of the landscape. Lawns also provide arenas for ricreational activities and relaxation. 3- Sport turfs provide enjoyement for partecipants and observers alike; football, baseball, soccer, golf, horse raiding are just a few of the many sports played, for the most part, on turf. Among sports, golf enjoys the longest and closests association with professional turfgrass managers. Many people consider Arlington, Va (USA), to be the birthplace of scientific turfgrass breeding in the years preceding World War II, thanks to the US Golf Association Green Section which assembled an exceptionally capable group of researchers to improve turgrass cultivars and management practices.

Turf quality Visual quality: - Density (measure of the number of aerial shoots per unit area) - Texture (from fine to coarse - measure of the width of the leaf blades) - Uniformity (estimate of the even appearance of the turf) - Color (measure of the light reflected by turf) - Growth habit (bunch-type, rhizomatous and stoloniferous) - Smoothness (surface feature of a turf that effects visual quality and playability) Functional quality: - Rigidity (resistance to the turfgrass leaves to compression, related to wear tolerance) - Elasticity (tendency of the leaves to “spring back” once a compressing force is removed) - Resiliency (capacity of a turf to absorb shock without altering its surface characteristics) - Verdure (measure of the amount of the aerial shoots remaining after mowing) - Rooting (amount of root growth evident at any one time during growing season) - Recuperative capacity (capacity of turfgrasses to recover from damages)

Turfgrass species All turfgrass species are within three subfamilies of Gramineae or Poaceae: Festucoideae (festucoid), Panicoideae (panicoid) and Eragrostideae (eragrostoid). Cool-season turfgrass – Turfgrass species adapted to favorable growth during cool portion ( ° C) of the growing season; may become dormant or injured during hot weather. Includes species of the festucoid subfamily. The ancestries of most of the major cool-season turfgrasses trace back to species native of cool, maritime climates of the British Isles and Northwestern Europe, as well as to the dry, hot-Summer/cool-Winter regions of Southern Europe. Warm-season turfgrass – Turfgrass species adapted to favorable growth during warm portion ( ° C) of the growing season; includes species of the eragrostoid and panicoid subfamilies. They are characterized by a slow geen up in Spring and late season discoloration. Creeping-type grasses – Turfgrass species characterized by extravaginal stem growth at or near the soil surface with lateral spreading by rhizomes and/or stolons. Bunch-type grasses – Turfgrass species characterized by intravaginal tillering at or near the soil surface without production of rhizomes and stolons.

CREEPING TYPE BUNCH TYPE

Characterization of some of the most important turfgrasses Cool-season grasses (Festucoideae subfamily) Festuceae tribe Creeping red fescue (Festuca rubra L. ssp. rubra and F. rubra L. ssp. trichophylla Gaud.). There are two distinct types of creeping red fescue: one that is a strong creeping type (spp. rubra) and a slender creeping type with short ryzomes (spp. trychophylla). Adaptation and use: well-drained, moderately shaded sites and drougthy, infertile, acid soils. Intolerant to wet conditions and high fertility. It is used in seed mixtures with Kentucky bluegrass in cooler climates and with perennial ryegrass for overseeding warm-season turf in subtropical climates for winter play and color. Cultural intensity: low to moderate. Mowing heights of 4-5 cm. Fertilization minimal: 100 kg N/ha/yr. Chewings fescue (Festuca rubra L. spp. commutata Gaud.). This is a noncreeping, bunch-type grass that is otherwise similar to creeping red fescue. Adaptation and use: compared to creeping red fescue, chewings forms a somewhat denser turf, especially under lower mowing height (about 2.5 cm). Chewings is somewhat less tolerant of temperature extremes than creeping red fescue; otherwise, the two are similar in their environmental adaptation. Cultural intensity: same as creeping red fescue.

Sheep fescue (Festuca ovina L.). A noncreeping, bunch-type grass with stiff, bluish-green leaves. Adaptation and use: well-drained, drougthy, sandy or gravelly, acid soils of low fertility. Used for soil stabilization. Cultural intensity: very low. Not adapted to intensive culture. Tall fescue (Festuca arundinacea Schreb.). Coarse-textured, bunch-type grass that is considered a good utility and sport turfgrass. Adaptation and use: adapted to a wide range of soil conditions. Heat and drougth stress tolerance especially good for a cool-season grass. Cold tolerance is relatively poor. Widely used as an utility turfgrass in warm, temperate and cool subtropical climates; its importance as lawn and sport species is increasing. Cultural intensity: low to moderate. Mowing range above 4 cm. Fertilization minimal: 100 kg of N/ha/yr.

Kentucky bluegrass (Poa pratensis L.). This is a highly variable, rhizomatous species with cultivars that differ in color, texture, density, close-mowing tolerance, disease resistance and other features. Adaptation and use: well-drained, moist, neutral and slightly acid, fertile soils on sunny or lightly shaded sites. Used throughout subartic and temperate climates and at high altitudes in tropical and subtropical climates. Widely used for lawns, sport and general purpose turfs. Cultural intensity: low to high, depending upon cultivar. Mowing tolerance range from 1,8 to 6 cm. Fertilization requirements: kg N/ha/yr. Perennial ryegrass (Lolium perenne L.). A bunch-type grass which may behaves as an annual, short-lived perennial, or perennial depending upon environmental conditions. Adaptation and use: moist, cool environments without severe winter or summer temperatures. Although adapted to a wide range of soil conditions, perennial ryegrass grows best in neutral to slightly acid, moist soils of moderate to high fertility. Used as a nurse turfgrass in cool-season turfgrass seed mixtures and in combination with Kentucky bluegrass for intensively trafficked athletic turfs. It is used in overseeding to promote recovery in Spring and provide a wear-tolerant turf during the playing season. Overseeding is also performed in dormant or semidormant, warm- season grasses for Winter play and color. Cultural intensity: moderate. Mowing height from 3,5 to 5 cm preferred. Fertilization requirements: kg N/ha/yr.

Aveneae tribe Creeping bentgrass (Agrostis stolonifera L.). A fine-textured, stoloniferous species, creeping bentgrass is the most widely used cool-season grass for golf and bowling greens. Adaptation and use: moist, fertile, acid or slightly acid soils. Used for greens, closely mowed tees and fairways and exotic lawns. Cultural intensity: high. Mowing heights of 0,5 – 1,25 cm preferred; fertilization kg N/ha/yr; irrigation frequent, topdressing helpful in controlling thatch. Colonial bentgrass (Agrostis tenuis Sibth.). A fine-textured, bunch-type to weakly creeping (short stolons and rhizomes) grass that is best adapted to temperate-oceanic climates. Adaptation and use: well-drained, sandy, acid to slightly acid soils of moderate fertility, poorly resistant to drought and heat stresses. Cultural intensity: moderate to high. Mowing heights of 0,7 to 2 cm: fertilization kg N/ha/yr; irrigation frequent during drought periods but less than that necessary to sustain creeping bentgrass.

Creeping bentgrass Identification of creeping bentgrass (Agrostis palustris Huds.) cultivars using Simple Sequence Repeats (SSRs) - Rutgers University (USA).

Warm-season grasses (Eragrostideae sub family) Chlorideae tribe Bermudagrass (Cynodon dactylon [L.] Pers.) A highly variable, warm-season species within which substantial differences exit in color, texture, density, vigor, and environmental adaptation. Lateral growth in by both stolons and rhizomes. Adaptation and use: adapted to a wide range of soil conditions. Although bermudagrass is generally not very cold resistant, the poleward limit of adaptation have been extended with the development of new cultivars. It is intolerant to shade and it is used for general purpose turf in lawns, sport fields and along roadsides. With the exception of common bermudagrass, all cultivars are propagated vegetatively. Cultural intensity: moderate to medium. Mowing heights of 1,2 – 2,5 cm are optimum. Fertilization 200 – 400 kg N/ha/yr. Some of the cultivars on the market are interspecific hybrids between C. dactylon and C. transvaalensis clonally propagated.

Zoysieae tribe Japanese lawngrass (Zoysia japonica Steud.). A medium textured, slow-growing, warm-season grass that spreads by stolons and rhizomes. It is adapted to tropical, sub-tropical, and temperate climates and characterized by a cold tolerance higher than bermudagrass. Adaptation and use: adapted to a wide range of soil conditions, but grows best on well-drained, slightly acid, medium-textured soils of moderate fertility. Cultural intensity: moderate to medium. Mowing heights of 1,2 – 2,5 cm are optimum. Fertilization kg N/ha/yr. Some of the cultivars on the market are interspecific hybrids between Z. japonica and Z. tenuifolia clonally propagated. Paniceae tribe Bahiagrass (Paspalum notatum Flugge). A tough, coarse-textured, rhizomatous, warm-season turfgrass adapted to tropical and warm subtropical climates. Adaptation and use: adapted to a wide range of soil conditions, but grows best on sandy, slightly acid, infertile soils. It can be propagated by seed and forms a tough, wear-resistant, open turf especially well suited for use along roadsides and for other utility turfs. Cultural intensity: low. Mowing heights 3,5 – 5 cm preferred. Fertilization 50 – 200 kg N/ha/yr.

Bahiagrass

Experimental field in Piemonte (North Italy)

Experimental field in Umbria (Central Italy).

Experimental field in Sicily

Different behaviour of P. pratensis cvs.

Festuca arundinacea

Poa pratensis

Festuca rubra rubra trychophilla commutata

Lolium perenne

Aerial view of Perugia (IT) experimental field.