The Effect of Endophyte on Salinity Tolerance in Perennial Ryegrass.

Perennial ryegrass (Lolium perenne L.), naturally contains symbiotic fungi known as endophytes (Neotyphodium lolii) which are known to confer above ground feeding insect resistance.  However, the role of endophytes in salinity tolerance in turfgrasses has not been widely studied.  The purpose of this study was to determine the role of endophytes in salinity tolerance in four different genotypes of perennial ryegrass.  Four perennial ryegrass clones (Brightstar SLT clone 5, Paragon GLR clone 4 [salt susceptible], 4501-7 and 4540-9 [salt tolerant]), with (E+) and without (E-) endophyte were grown under control (0.5 dS m^-1) and saline water conditions (15 dS m^-1).    Control and saline water treatments were applied to sixweek old transplanted plants in sand using an overhead irrigation chamber in a greenhouse.   Three replications of each clone per treatment were arranged in a randomized complete block.  Plants were irrigated every other day and ratings of percent green were taken weekly.  Leaf clippings were harvested biweekly and dried and weighed.

            The entire experiment was repeated three times. Salinity treatments reduced shoot weights by 18-35% and root weights by 46-63% across runs.  Endophyte had no effect on salinity tolerance in three of the four perennial ryegrass genotypes, while in Paragon GLR, E- plants were significantly more salt tolerant than E+ plants in two runs.  This variability is consistent with endophyte effects on drought tolerance and indicates that the role of endophytes in salinity tolerance is minimal and/or specific to the interaction of individual genotypes and fungal isolates.