Germination of Fourwing Saltbush Seeds: Interaction of Temperature, Osmotic Potential, and pH

Abstract

Establishment of shrubs and other forage plants on arid and semiarid rangelands and salt-contamhtated sites may be enhanced ifecotypes with ability to germinate and establish under moisture stress and high temperatures can be identified. The interactive effects of temperature, osmotic potential, and pH on germination were evaluated with seed from 4 populations of fourwing saltbush [Atr@lex canescens (Pursh) Nutt.] from western Texas. Predicted optimum temperature (15 to 18' C) from osmotic potential by temperature response surfaces for germination of 3 populations (Valentine, Grandfalls, and San Angelo) were similar to those reported for populations of fourwing saltbush from other western states. Germination of seed collected near Texon, Texas was significantly (JYO.01) affected by media pH range 6 to 9. Seed from the Texon population germinated under lower osmotic potentials compared to the other 3 populations. Total germination of all four populations was enhanced by osmotic potentials lower than 0 MPa. Seed from the Texon population may possess germination characteristics more suitable for arid-hmd seeding than those from populations near Valentine, Grandfalls, and San Angelo, Texas. Fourwing saltbush [Atriplex canescens (Pursh) Nutt.], a native, evergreen shrub, is absent or rare on most western Texas rangeland, probably because of the prevalence of continuous, yearlong grazing by cattle, sheep, and/or goats. The species has been successfully used for rehabilitation of oilwell reserve pits where high concentrations of soluble salts and sodium prevented acceptable establishment or growth of other species.1 Our preliminary grazing trials suggest that fourwing saltbush may be valuable for balancing the seasonal deficiencies of protein in native forages (D.N. Ueckert, unpublished data). Fourwing saltbush frequently grows on relatively dry, saline Authors are reseach associate, professor, and research associate, Texas Agricultural Experiment Station, 7887 N Hwy 87, San Angelo 76901 and Grounds Keeper, University Lands,

Plant life-form and germination in a Mexican inter-tropical desert: effects of soil water potential and temperature

“…Potter et al (1986) found that some populations of the North American shrub, Atriplex canescens had higher germinability at low water potential, than other populations of this species. Also, Choinski & Tuohy (1991) found that the South African shrubs Combretum apiculatum and Colophospermum mopane had high germinability over a wide range of soil water potentials.…”

“…There are groups of species in which optimum germination temperatures coincide with the average summer or winter temperatures of their local habitats (Went, 1949;Juhren et al, 1956;Tevis, 1958;Beatley, 1974;Friedel et al, 1988;Jurado & Westoby, 1992;Gutterman, 1993). Other investigations have documented that when seed germination temperature is close to the optimum, water potential become less limiting (Scifres & Brock, 1969;Knipe, 1973;Bokhari et al, 1975;Hegarty, 1975;Potter et al, 1986;Romo & Haferkamp, 1987;Cluff & Roundy, 1988;Eddleman & Romo, 1988;El-Sarkawi & Farghali, 1988;Romo et al, 1991;Qi & Redmann, 1993;Dahal et al, 1996).…”

“…Two critical steps in the life-cycle of most plant species are seed germination and seedling establishment (Kozlowski & Gunn, 1972;Harper, 1977;Gutterman, 1993;Esler & Phillips, 1994). It has been suggested that, in desert environments, soil water potential (SWP) and temperature are the key factors affecting seed germination (Potter et al, 1986;Cluff & Roundy, 1988;El-Sharkawi & Farghali, 1988).…”

“…In arid zones some species germinate at water potentials lower than !0)8 MPa (Potter et al, 1986;BriedeH & McKell, 1992;Qi & Redmann, 1993;Facelli & Ladd, 1996;IbaH n ez & Passera, 1997;Larson & Kiemnec, 1997;Adams, 1999). This is not surprising since high SWP are rarely achieved in the soil surface of arid environments.…”

“…This is not surprising since high SWP are rarely achieved in the soil surface of arid environments. Furthermore, it has been reported that some plant species exhibit an inverse correlation between germination and substrate water potential until a lower threshold below which germination decreases (Potter et al, 1986;IbaH n ez & Passera, 1997).…”