ious salts on seed germination. Various salts that are common in saline soils were selected, including NaCl,
Na 2 SO 4 , MgSO 4 , KCl, and CaCl 2. A single salt solution at concentrations of 100, 1000, 5000, and 10,000
ppm was used. The aim of this investigation was to understand how a plant species from different locali-
ties behaves with a particular salt and whether the inhibition of germination is due to the osmotic or toxic
effect of different ions. To make a distinction between the osmotic and ionic or the combined effect of these
two factors on seed germination inhibition, the seeds that remained ungerminated in the saline-medium at
10,000 ppm were transferred to distilled water individually to determine the additional germination per
treatment.
The results revealed that the germination percentage varied with different salt solutions [92]. Higher
concentrations of all the salts directly affected germination, and the germination percentage was reduced.
The seeds of C. creticacollected only from site I showed dormancy, and no germination was observed in
the control. No salt solution could improve the germination percentage. The maximum (40%) germina-
tion was recorded with 100 ppm Na 2 SO 4. The seeds of Z. simplexhad severe dormancy because no ger-
mination was observed either in the control or in any salt solution [93]. However, Khan and Ungar [94]
reported that growth regulator treatments increased germination to over 80% in nonsaline conditions in
Zygophyllum simplex.
After 10 days of salt treatments, ungerminated seeds from the 10,000 ppm concentration of five salt
solutions were individually transferred to distilled water. It was discovered [91] that the germination in-
hibition in saline media was due to osmotic stress or specific ion toxicity because the germination per-
centage increased when seeds were transferred from salt solution to distilled water (Table 3) [91,95].
Variation in temperature appears to play an important role in recovery of germination of halophytes from
salt stress when seeds are transferred to distilled water [96].
Mohammed and Sen [91] proved that higher concentrations of salts retarded germination because of
osmotic effects, as the process of seed germination speeded up after transfer to nonsaline medium. There
was up to 80% recovery of germination for seeds of Suaeda fruticosathat initially did not germinate in
500 mM NaCl [97]. This may be of significance under natural conditions, especially for inland desert
salines, because seeds that could not germinate under extreme salinity stress may have evolved a mecha-
nism to germinate rapidly when the salt stress is relieved [10,15,98–100]. Although NaCl is the major salt
in most salt-affected soils, other salts also present in the soil play a combined role in the salt tolerance of
a species at the time of germination.
Gibberellic acid and kinetin significantly alleviated the inhibitory effects of salinity on germination
of seeds in Arthrocnemum indicumbut over different salinity ranges and to different degrees. Both growth
regulators significantly increased the rate of germination over most salinities, but the effect of gibberel-
lic acid was more pronounced than that of kinetin [101].
Haloxylon recurvumandH. salicornicumare two characteristic halophytes of the Indian desert. Ex-
tremely fast germination in the seeds of these two species, commonly occurring within an hour, has been
570 SEN ET AL.
TABLE 3 Additional Mean Germination Percentage of Some Halophytic Species Observed After Transfer
of Ungerminated Seeds from 10,000 ppm Concentration of Each Salt Solution to Distilled Water After 10
Days
Salt solutionsSpecies Site NaCl Na 2 SO 4 MgSO 4 CaCl 2 KCl
Salsola baryosma I36 16 23 1040
III 53 13 23 20 40
Sesuvium sesuvioides I20 10 20 7040
II 10 13 16 20 50
III 13 16 10 30 10
IV 16 20 13 60 10
Trianthema triquetra I16 30 20 1330
II 10 10 13 10 10
III 13 13 10 10 10
Suaeda fruticosa I36 26 16 2020
II 40 26 30 16 26
III 40 30 10 30 26
Source:Ref. 91 and 95.