Bermudagrass is native to Africa, widely distributed, and commonly found in tropical and subtemperate areas (Taliaferro et al., 2004). It is important for forage, turfgrass use, and soil and water conservation. Hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy] is widely used on golf courses, sport fields, and other high-maintenance turf areas in the United States (Hanna et al., 2013). Bermudagrass, a warm-season grass, lacks winterhardiness, which limits its use through the transition zone and into the northern part of the United States (Munshaw et al., 2004). Although scientists have developed and released bermudagrass cultivars with improved cold hardiness, the relative salinity tolerance of many of these releases has not been studied.
Salinity limits plant growth and production. Over 45 million hectares of irrigated land around the world have been affected by saline soil issues; 1.5 million hectares lack vitality due to soil salinity (Carillo et al., 2011; Munns and Tester, 2008). Since potable water scarcity is a growing problem as well, government-mandated water use restrictions are wide spread and this often requires the use of reclaimed water high in salinity (Marcum and Pessarakli, 2006). In response to these pressures, research has been done on turfgrass growth responses to different water-saving strategies, such as responses to saline water irrigation (Sevostianova et al., 2011). Finding ways to satisfy the need of water for human activities, while at the same time protecting the freshwater systems, now ranks among the 21st century’s most critical challenges.
Saline-tolerant plants can minimize inimical saline effects by generating a series of processes in the morphological, physiological, and biochemical levels (Jacoby, 1999; Uddin et al., 2011). Saline-tolerant bermudagrass cultivars could produce acceptable quality turf in areas where there is reclaimed water irrigation or soil saline issues (Uddin et al., 2011). Marcum (2008) ranked Cynodon sp. as possessing excellent salinity tolerance turfgrass, but he also found that the salinity tolerance within the species is highly variable. Information on the relative salinity tolerance of bermudagrass cultivars and experimental selections will provide turfgrass breeders and managers with a greater selection pool.
In addition, it is important to determine the effectiveness of subjective and nondestructive evaluation parameters for plant salinity tolerance. NDVI has been used to evaluate TQ and drought response (Leinauer et al., 2014), but little work has used NDVI to evaluate salinity response in turf (Bell and Xiong, 2008). Recently, additional NDVI sensors and smartphone applications (App) have been marketed for turf evaluation, but little has been published regarding the effectiveness of these tools.
The objectives of this research were to 1) determine the relative salinity tolerance of clonal-type bermudagrass, including six industry standards and one OSU experimental line; 2) evaluate the response of the seven bermudagrass entries to salinity stress using the GreenSeekerTM handheld sensor (Trimble Navigation LTD, Sunnyvale, CA), the FieldScout® CM 1000 NDVI meter (N-Tech Industries Inc., Ukiah, CA), and the FieldScout® GreenIndex+ Turf App (Spectrum Technologies Inc., Aurora, IL) compared with the traditional visual TQ ratings and DIA.
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