Growth response of four turfgrass species to salinity

The need for salinity tolerant turfgrasses is increasing because of the increased use of effluent or other low quality waters for turfgrass irrigation. Greenhouse container and hydroponic experiments were conducted to determine the relative salinity tolerance and growth responses of ‘Challenger’ Kentucky bluegrass (Poa pratensis L.) (KBG), ‘Arid’ tall fescue (Festuca arundinacea Schreb) (TF), ‘Fults’ alkaligrass (Puccinellia distans (L.) Parl.) (AG), and a saltgrass (Distichlis spicata (Torr.) Beetle) collection (SG). In the container experiments, irrigation waters of different salinity levels were applied to experimental plants grown in plastic pots filled with a mix of sand and Isolite. The results indicated that KBG, TF, AG, and SG experienced a 50% shoot growth reduction at 4.9, 10.0, 20.0, and 34.9 dS m−1, respectively, and a 50% root growth reduction at 5.8, 19.6, 24.9 and 41.0 dS m−1, respectively. In the hydroponic experiment, grasses were grown in saline solution at 2.0, 4.7, 9.4, 14.1, 18.8, and 23.5 dS m−1. Kentucky bluegrass, TF, AG, and SG experienced a 50% shoot growth reduction at 5.5, 14.2, 23.0, and 34.5 dS m−1, respectively, and a 50% root growth reduction at 7.9, 21.5, 30.4 and 40.8 dS m−1, respectively. Root to shoot ratio of KBG remained constant, whereas those of TF, AG, and SG increased at all salinity levels. Salinity caused root cortex cells to collapse, in KBG at 14.1 dS m−1 and in TF at 23.5 dS m−1. Alkaligrass and SG only had a few cell collapses even at 23.5 dS m−1. Bi-cellular salt glands were observed only on leaves of SG. The ranking for salinity tolerance of selected grasses was: SG>AG>TF>KBG. Salt glands present in SG, root growth stimulation of SG and AG, and maintenance of relatively high root to shoot ratio in TF are apparent adaptive mechanisms exhibited by these grasses for salinity tolerance.