Physiological and ecological aspects of salt tolerance in grasses native to Minnesot

Sodium chloride (NaCl) is the most common deicing salt used to improve winter driving conditions on roadways in Minnesota. NaCl impairs plant establishment along roadsides and adversely affects roadside soils. Experiments were devised to evaluate two approaches for aiding roadside plant establishment: applying soil amendments to alleviate NaCl stress and adding salt tolerant native grasses to roadside plantings. Soil amendments (gypsum, potash, and potassium nitrate) were tested in greenhouse and field studies for their ability to alleviate NaCl-induced stress on the emergence of three grass species with varied abilities to tolerate NaCl (Poa pratensis, Bouteloua gracilis , and Puccinellia distans) that are commonly planted along roadsides. Gypsum alleviated NaCl stress more profoundly than potash or potassium nitrate. Low concentrations of potash and potassium chloride alleviated NaCl stress whereas higher concentrations exacerbated NaCl stress. Seeds from two populations of Puccinellia nuttalliana and Distichlis spicata var. stricta were collected from unique, highly saline soils in Kittson and Lac Qui Parle counties in Minnesota and evaluated for their ability to germinate and grown in soils with increased NaCl content. The response of the P. nuttalliana populations to various NaCl concentrations was also compared to that of two P. distans cultivars ('Fults' and 'Salty'), a non-native species commonly planted along roadsides in Minnesota. The native grass populations differed in their response to increased NaCl; plants of both P. nuttalliana and D. spicata var. stricta from the Lac Qui Parle (Salt Lake) population demonstrated greater tolerance across germination, biomass, height, and flowering parameters. The P. distans cultivars demonstrated high tolerance of and less overall variability in response to increased NaCl. The Salt Lake population of P. nuttalliana was quantitatively similar to the P. distans cultivars across measured parameters, although was qualitatively lower in salt tolerance.