Greenhouse studies were conducted to determine the relative salinity
tolerance of foxtail barley and seven desirable pasture grasses. Grass
species were reed canarygrass, timothy, altai wildrye, tall fescue, tall
wheatgrass, orchardgrass, creeping meadow foxtail, and foxtail barley.
Grasses were exposed to increasing electrical conductivity levels of NaCl
and CaCl2 salt solution over time. Grass species were compared
using a cumulative value of salt exposure (ECdays), which was
calculated to account for the electrical conductivity (EC) and the time a
plant was exposed at that level of conductivity. Salinity tolerance varied
among grass species. Increasing EC significantly reduced plant biomass of
all species. All grass species experienced a 50% biomass reduction
(GR50) between 271 and 512 ECdays in 2008 and
between 297 and 575 ECdays in 2009. Foxtail barley was among the
most salt tolerant (GR50 = 512 and 525 ECdays),
requiring the highest salt exposure in 2008 and the second-highest exposure
in 2009 to reduce biomass 50%. Grass mortality increased with increasing EC
levels. Reed canarygrass and timothy were most susceptible to increasing
salinity, with 50% mortality (LD50) of both grass species
occurring between 983 and 1,186 ECdays. Moderate salinity
tolerance was exhibited by orchardgrass, which required 1,977 and 1,844
ECdays; creeping foxtail, which required 1,998 and 2,431
ECdays; and tall fescue, which required 2,501 and > 2,840
ECdays to LD50 in 2008 and 2009, respectively.
Foxtail barley, altai wildrye, and tall wheatgrass were most tolerant of
salinity and persisted with little mortality occurring at 3,033 and 2,840
ECdays in 2008 and 2009, respectively. All grass species with
higher growth rates than foxtail barley and altai wildrye were more
susceptible to salinity, with the exception of tall wheatgrass. Growth rates
of foxtail barley and altai wildrye were less than they were for other
grasses, suggesting that slower growth rates may aid in salinity
tolerance.