Germination of the Salt-Tolerant Grass Diplachne fusca. II. Salinity Responses

Abstract

The responses -of germination of the salt-tolerant grass Diplachne fusca (L.) Beauv. to salinity and various temperature regimes are described. At temperatures of 30/20°C (12 h light and dark periods), final germination was 70% in distilled water, decreased to 50% in 175 mol m-3 NaCl (π = - 0.8 MPa) and 7% in 380 mol m-3 NaCl (π = -1.8 MPa). Increasing salinity from 0-130mol m-3 NaCl decreased the final germination percentage, but did not modify the threshold temperatures (day or night temperature > 27°C) at which germination occurred. Presoaking in distilled water or 1% CaCl2· 2H20 solution did not significantly affect the final germination percentage of seeds which were subsequently placed in solutions with a range of salinities from 0-210 mol m-3 NaCl (*#960 = 0 to - 1.0 MPa). How- ever, addition of CaCl2 to NaCl solution increased the final germination percentage compared with that in pure NaCl solution. Presoaking in concentrated (400 mol m-3) NaCl solution caused a decrease in subsequent germinability of 20 or 40% in 0 and 40 mol m-3 NaCl, respectively. Under field conditions (in soil with mean daily maximum temperature of 33°C and mean daily minimum temperature of 15°C), rates of seedling establishment were similar (16% of seed sown) in soils irrigated with 0 or 50 mol m-3 NaCl, and were 1% in those irrigated with 100 mol m-3 NaCl. The inhibition of germination in NaCl solution was largely an osmotic effect since there was a similar reduction in the final germination percentage in iso-osmotic solutions of NaCl and mannitol. However, the proportion of seeds germinating in NaCl solution was enhanced by adding calcium. The inhibition of germination was greater in sulfate solutions compared with that in chloride solutions and, to a lesser degree, in potassium compared with sodium solutions. The practical implications of our results are discussed. The incorporation of gypsum into the soil and measures to leach salts from the topsoil are recommended before D. fusca is sown on saline land.

Effects of sodium chloride on seed germination and growth of two Chinese desert shrubs, Haloxylon ammodendron and H. persicum (Chenopodiaceae)

“…Seeds that germinate better in NaCl than in isotonic PEG solutions have been reported for some other species (Sharma 1973;Romo and Eddleman 1985;Tobe et al 1999). The Ψ W of the NaCl solution that inhibited germination of both H. ammodendron and H. persicum was rather low compared with those that inhibit germination of many halophytic species (Partridge and Wilson 1987;Myers and Morgan 1989;Khan and Rizvi 1994;Khan and Ungar 1996;Ungar 1996). For example, the seeds of two tested species germinated in an NaCl concentration about twice the maximum possible for seeds of a halophyte Haloxylon recurvum (Khan and Ungar 1996).…”

The effect of plant growth regulators, nitric oxide, nitrate, nitrite and light on the germination of dimorphic seeds of Suaeda salsa under saline conditions

“…Seed dimorphism and polymorphism are reported in many halophytic species including Arthrocnemum, Chenopodium, Atriplex, Cakile, Salicornia, Salsola, Spergularia, and Suaeda growing under saline conditions (Khan and Ungar 1984a, b;Mohammad and Sen 1988;Myers and Morgan 1989;Ungar 1991;Khan et al 2001Khan et al , 2004. S. salsa produces brown and black seeds on the same plant; this appears to a useful strategy to increase chances for population establishment under variable temperatures and soil salinities (Ungar 1995).…”

Osmotic and toxic ion effects on seedling emergence and nutrition of citrus rootstocks

“…To distinguish between osmotic effect and ion toxic effect of salts, the effects of isosmotic solutions of NaCl, PEG, and mannitol were compared. Supplemental Ca to the osmotic and saline solutions was also examined because Ca had been shown to mitigate the adverse effects of salts and improve germination and growth of several crops (Cramer et al, 1987;Hyder and Greenway, 1965;Kent and Lauchli, 1985;Marcar, 1986;Myers and Morgan, 1989;Norlyn and Epstein, 1984;Zekri, 1993a;Zekri and Parsons, 1990a). …”