27. Relative Salinity Tolerance of 35 Lolium spp. Cultivars for Urban Landscape and Forage Use

Increasing population growth, particularly in urban centers, is resulting in critical freshwater shortages for both agriculture and urban use worldwide. To counteract existing water crises, many governments are restricting use of freshwater sources for irrigation. In the urban setting, governments are requiring use of reclaimed wastewater or other secondary saline water sources in lieu of freshwater for landscape irrigation. Lolium spp. (ryegrasses) is widely used for forage as well as in urban turf landscapes. Relative salinity tolerance of 35 Lolium spp. cultivars was determined in solution culture by measuring changes in shoot weight, root weight, rooting depth, and % green leaf canopy area, relative to control (non-salinized) plants. There was a wide range in salinity tolerance of the tested cultivars, ranging from salt tolerant (e.g., cv. Paragon) to salt sensitive (e.g., cv. Midway). All shoot parameters were highly correlated, being mutually effective predictors of salinity tolerance. Root dry weight, significantly correlated with all shoot quality and growth parameters, was also effective in predicting relative salinity tolerance. However, rooting depth was not correlated with other parameters, and therefore not effective in predicting relative salinity tolerance. Based on these results, it is concluded that salt-tolerant cultivars exist within Lolium spp. for agricultural forage and urban landscape use.