In the transition zones of the Mediterranean Europe, including most of Italy, turfs are mostly composed of cool-season species. Maintaining cool-season grasses in these areas has been questioned because of their high irrigation requirements relative to warm-season species. Cool-season turfgrasses use more water than warm-season grasses due to their higher evapotranspiration rates during the summer months and longer growing period. Evapotranspiration rates for warm-season grasses range from 2 to 5 mm·d−1 compared with 3 to 8 mm·d−1 for cool-season grasses (Casnoff et al., 1989; Huang, 2008). Although warm-season turfgrasses are best adapted to warm climates, they can be successfully grown in transitional environments (de Bruijn, 2010; Volterrani et al., 2004). To reduce water consumption for landscape irrigation, their use could be encouraged in Mediterranean countries of Europe.
Winter dormancy and poor tolerance to low temperatures represent the main impediments to warm-season grasses gaining greater acceptance in the Mediterranean countries. In transition zones, warm-season grasses lose color in autumn and are susceptible to low temperature injury during the cooler months (Beard, 1973; Munshaw et al., 2006; Richardson, 2002). In some transition zone regions, the warm-season turfgrasses remain dormant for up to 5 months, which strongly inhibits their widespread use. However, low temperature tolerance and spring green-up can be improved through appropriate cultivar selection and the application of proper management practices (Anderson et al., 2007; Patton et al., 2008).
Bermudagrass, currently, is the warm-season turf species most widely used in the European countries because of its recuperative potential, wear tolerance, and pest resistance (Beard, 1973; Croce et al., 2003). In transition zones, bermudagrass may be used in pure stands or overseeded in the fall with cool-season grasses, such as perennial ryegrass (Lolium perenne) or annual ryegrass (Lolium multiflorium) to provide year-round green color (Goddard et al., 2008; Schmidt and Shoulders, 1980).
The spring green-up of bermudagrass in the transition zone has been an important issue for many years. Bermudagrass spring recovery usually begins when the soil temperature reaches 10 °C and the active growing period continues until the soil temperature decreases below this level in the fall (Youngner, 1959). Several studies have reported on the role of carbohydrates in turfgrass spring shoot renewing (Macolino et al., 2010; Rogers et al., 1975; Trenholm et al., 1998). Nonstructural carbohydrates are accumulated in storage organs (stolons and rhizomes) of turfgrasses in autumn during cold acclimatation and used in spring as an energy source to support the spring green-up (Stier and Fei, 2008). The speed to recovery after winter dormancy has been considered a main factor in selecting bermudagrass cultivars for the transition zones (Patton et al., 2008; Richardson et al., 2004). Spring green-up has been studied with emphasis on fertilization (Goatley et al., 1994; Miller and Dickens, 1996a, 1996b; Trenholm et al., 1998) and other management practices, such as winter turf covers (Goatley et al., 2005) and plant growth regulators (Richardson, 2002; White and Schmidt, 1989). Collectively, these studies demonstrated that great potential exists for accelerating the spring green-up of bermudagrass through the application of appropriate cultural practices and cultivar selection.
During the growing season, removing more than 40% of the turf height in a single mowing can cause scalping, resulting in unattractive patches and exposure of the lower part of the plants (Beard, 1973). However, the deliberate application of scalping in early spring removes dead leaf tissue and allows sunlight to reach the new growth next to the ground and can allow for earlier spring green-up (Brede, 2000; Christians, 1998). Despite the suggested use of this cultural practice, no studies have been published on the effectiveness of spring scalping in promoting green recovery. To address this knowledge gap, the influence of spring scalping on spring green-up of eight bermudagrass cultivars was studied for 2 years in a transition zone environment.
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