Germination responses of desert saltgrass to temperature and osmotic potential

Desert saltgrass [Distichlis spicata var. stricta (Torr.) Beetle] is the dominant herbaceous forage on many saline rangelands. The ability to direct-seed this grass would permit revegetation of disturbed saline soils. Seeding guidelines must be based on an understanding of germination requirements in relation to seedbed conditions. Germination responses to alternating temperatures in relation to sodium chloride (NaCl)-reduced osmotic potentials were studied in the laboratory and seedbed salinity and water potentials were measured in a typical saltgrass stand in Nevada. Optimum conditions for saltgrass germination were at -0.1 MPa osmotic potential and a 20 degrees C differential in cold and warm period temperatures with warm period temperatures above 30 degrees C. Decreasing osmotic potentials from 0 to -2 MPa decreased the rate of germination from 4.5 to 0.3 and total germination from 60 to 9% across all temperature regimes. Water potentials in the lower topographical positions of a typical saltgrass stand after an unusually wet winter were high enough for germination (>-2MPa) in June when temperatures were optimum for germination. In most years and on xeric sites, optimum temperature and moisture conditions would not overlap to result in high germination. Some germination occurs at cooler than optimum temperatures and low osmotic potentials. Some seeds may eventually germinate in saline seedbeds under these conditions but highest germination would be expected when unusually high precipitation or topographic position results in high seedbed water potentials during late spring and early summer when temperatures are optimum. Consequently, irrigation during late spring and summer should produce the best stands of saltgrass from direct seeding. Where irrigation is not possible, saltgrass should be seeded in the fall to permit germination during early spring when temperatures are suboptimum but the seedbed is still moist. Success of nonirrigated seedings will be highly dependent on seedbed salinity and moisture conditions in the spring.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact lbry-journals@email.arizona.edu for further information.Migrated from OJS platform August 202