GERMINATION OF KALIDIUM CASPICUM SEEDS

Wang, L., Zhang, D.Y., Huang, Z.Y. and Tian, C.Y. (2009), Seed Sci. & Technol., 37, 281-290 Factors influencing seed germination of Kalidium caspicum (Chenopodiaceae), a halophytic desert of ,

L. WANG1, 2, D.Y. ZHANG1, Z.Y. HUANG2 AND C.Y. TIAN1

1 Key Laboratory of Oasis Ecology and Desert Environment, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, PR China (E-mail: [email protected] or [email protected]) 2 The State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, PR China

(Accepted July 2008)

Summary

Kalidium caspicum, a halophytic shrub in the family Chenopodiaceae, is native to the inland salt deserts of Xinjiang. The effects of light, temperature and NaCl on seed germination and germination recovery were determined. With increased exposure to light, seed germination gradually decreased. The sequence in which seeds were exposed to light also influenced germination. The optimal temperature for germination was 25 to 30°C. An increase in NaCl concentration progressively inhibited seed germination, with the critical salinity tolerance for seed germination 198mmol.L-1NaCl, and the ultimate salinity tolerance is 278mmol.L-1NaCl. Seeds were not affected by ion toxicity as evidenced by high germination recovery percentage and pink embryos of ungerminated seeds in solution of 2, 3, 5-triphenyl-2H-tetrazolium chloride (TTC). At high temperature (35°C), some seeds did not recover germination and entered second dormancy in different NaCl solution. This phenomena indicates that exposure to high temperatures prevents germination in saline soils. The "cautious" strategy allows seeds of K. caspicum to avoid injury from salt and may play an important role in germination under desert conditions.

Introduction

Kalidium caspicum Ung.-Sternb. (Chenopodiaceae), a stem-succulent halophytic shrub, occurs in saline and alkaline mud flats and salt-lake shores in the desert regions of northern Xinjiang, China (Zhu et al., 2003). It is often found in association with Kalidium foliatum (Pall.) Moq., Suaeda acuminata (C.A. Mey.) Moq. and Suaeda physophora Pall. Seeds of K. caspicum mature from late September to early November and most of them are dispersed on the shallow layer of saline soil around the parent . Growth and development of the plant are conditioned by time and place of seed germination (Casal and Sánchez, 1998), which is a crucial stage in the life cycle of in saline environments as it determines whether or not plants can establish successfully in certain areas (Song et al., 2005). Germination of halophytes in the field is controlled by several environmental factors, in particular light (Merritt et al., 2006; Batlla et al., 2007), temperature (Baskin and Baskin, 1989; Baskin et al., 1998), salinity (Keiffer and Ungar, 1997; Khan et al., 2004) and interactions among them (Gul and Weber, 1999; Zia and Khan, 2004).

281 L. WANG, D.Y. ZHANG, Z.Y. HUANG AND C.Y. TIAN

Halophyte seeds are known to maintain viability for extended periods of time during exposure to high salinity, initiating germination when salinity is reduced (Khan and Ungar, 1998; Zia and Khan, 2004). The response of seeds of desert halophytes can be divided into two broad groups with respect to salt resistance: germination under hypersaline conditions; or no germination during exposure to high salinity and germination recovery when salinity stress is alleviated. In the first group, seeds that can germinate under hypersaline conditions usually suffer ion toxicity; in the second group, seeds that only germinate in low salinity may have a complete germination recovery (Huang et al., 2003; Zia and Khan, 2004; Song et al., 2006). Germination recovery is affected by the temperature regime to which seeds are exposed after they are transferred from NaCl solution to distilled water, and subsequently from initial designed temperature regimes to optimum temperature (Khan and Ungar, 1997; Song et al., 2006). Different aspects of germination of K. caspicum have been investigated by Tobe et al. (2000, 2002), Li and Zhang (2007) and Qu et al. (2008a). However, the effects of different light periods and light sequences, the interaction between temperature and NaCl, germination recovery percentage, and the critical and ultimate salinity tolerance of seed germination are still unknown. Tobe et al. (2000) found that germination of K. caspicum were nearly the same in light and dark at 10, 15, 20, 25 and 35°C; whereas Qu et al. (2008a) reported that germination percentages were significantly influenced by light. The objectives of this study were to (a) determine the effect of light, temperature and salinity on seed germination and germination recovery; (b) determine the critical and ultimate salinity tolerance of seed germination of K. caspicum.

Materials and methods

Soil samples collection Soil samples were collected from six randomly chosen areas within the study population of K. caspicum in October 2004 and analyzed using the residue drying quality measure (Bao, 2000).

Seed collection Mature seeds (utricles) of K. caspicum (44°07' N; 87°46' E) were randomly collected from the whole population of plants growing in saline soil in Fukang, Northern Xinjiang, China, in October 2004, and dry seeds (moisture content 9.5 ± 0.3%) were stored in sealed plastic bags at 4°C until used.

Effect of light on germination Seeds were incubated in 5cm diameter, tight-fitting Petri dishes on three layers of filter paper moistened with 3mL of distilled water, in a climatic chamber (Conviron 125L; Controlled Environments. Limited, Winnipeg, Canada; 75µmol.m-2.s-1, 400-700nm). Four replicates of 25 seeds each were used per treatment. Seeds were considered germinated once the radicle emerged. Seeds that had been stored dry at 4°C for 12 months were incubated in distilled water under various light conditions (24 hr light; 12 hr light/12 hr

282 GERMINATION OF KALIDIUM CASPICUM SEEDS darkness; 12 hr darkness/12 hr light; 24 hr darkness, including 5 min light irradiated after 12 hr darkness; 24 hr darkness) at 25°C. Germination in light was assessed every 24 h, and germinated seeds were removed from the Petri dishes. Seed germination under total darkness was checked after eight days. Final seed germination percentage was calculated after eight days.

Effect of temperature and salinity on germination Seeds were sown on three layers of filter paper moistened with 3mL of either distilled water or with one of a range of concentrations of NaCl in petri dishes which were sealed with plastic film to prevent evaporation, and incubated at 10, 15, 20, 25, 30 and 35°C at 0, 50, 100, 150 and 200mmol.L-1 NaCl under constant darkness except for 5 min light irradiated after 12 hr darkness. Final seed germination percentage was calculated after 10 days. Viability of ungerminated seeds was determined using the 2,3, 5-triphenyl-2H- tetrazolium chloride (TTC) test (Baskin and Baskin, 1998). Seeds were placed in a 1.0% solution of TTC for 24 hr at 30°C.

Recovery test First recovery: Ungerminated seeds from the 10 day NaCl pre-treatments were rinsed three times in distilled water and then transferred to 5cm diameter Petri dishes on three layers of filter paper moistened with 3mL of distilled water. Seeds were incubated at initial designed temperatures (10, 15, 20, 25, 30 and 35°C) for five days. Second recovery: Ungerminated seeds in each Petri dish in the first recovery test were subsequently transferred to 5cm diameter Petri dishes on three layers of filter paper moistened with 3mL of distilled water at 25°C for another five days. The germination was recorded.

Data analysis Seed germination percentage was expressed as mean ± s.e. The rate of germination was estimated using a modified Timson’s index of germination velocity = ∑G/t, where G is germination percentage at 24 h intervals and t is the total germination period (Khan and Ungar, 1997). The maximum value possible for our data using this index was 100 (i.e., 1000/10). The recovery percentage was calculated according to the following formula: [(a - b)/(c - b)] × 100, where a) is the total number of seeds germinated in salt solution plus those that recovered to germinate in the distilled water after the ungerminated seeds moistened in NaCl for 10 days were transferred to 5cm diameter Petri dishes on three layers of filter paper moistened with 3mL of distilled water for five days, b) is the number of seeds germinated in salt solution and c) is the total number of seeds tested (Gul and Weber, 1999). The final germination was calculated by the equation [(d + e + f) /c] × 100, where d) is the total number of seeds germinated in salt solution for 10 days, e) the total number of seeds germinated in distilled water after the ungerminated seeds in salt solution were transferred to distilled water for five days, f) the total number of seeds germinated in distilled water after the ungerminated seeds in each Petri dish in the recovery experiment for five days were subsequently transferred to distilled water at 25°C for another five days and c) the total number of seeds (Song et al., 2006).

283 L. WANG, D.Y. ZHANG, Z.Y. HUANG AND C.Y. TIAN

To determine the critical salinity tolerance and ultimate salinity tolerance of seed germination of K. caspicum, a unitary quadratic equation was used to represent the relationship between germination percentage of K. caspicum and different concentrations of NaCl solution. The critical value of salinity tolerance of seed germination of K. caspicum is the concentration of NaCl for which germination is 50% at the optimum germination condition, and the ultimate value of salinity tolerance is the concentrations of NaCl for which the germination percentage is 0 at the optimum germinating condition. Germination data were transformed (arcsine) to ensure homogeneity of variance before a statistical analysis was performed. The data were analyzed using SPSS Version 12.0 for Windows. A one-way or two-way ANOVA was used to demonstrate the significance of light, temperature and salinity and their interaction in affecting seed germination percentage. Tukey’s test was used to determine differences among treatments at P = 0.05.

Results

Soil conductivity Soil samples had mean total soil salinities in the 0-5, 5-10 and 10-30 cm soil layers of 0.28 ± 0.08%, 0.45 ± 0.13%, 0.72 ± 0.11%, which are equal to NaCl concentrations of 50 ±14, 80 ± 23, 120 ± 20mmol.L-1, respectively.

Effect of light on germination Germination was significantly influenced by light, although germination in 24 hr constant light did not differ significantly from that in 12 hr light/12 hr darkness, which differed significantly from that in 12 hr darkness/12 hr light. There was no difference among germination in 12 hr darkness/12 hr light, or 24 hr darkness (with 5 min light irradiated after 12 hr), and 24 hr darkness. Highest germination was obtained in 24 hr darkness; lowest germination was obtained in 24 hr light (figure 1).

100 bb

80 b

60

40 a Germination (%) 20 a

0 24L 12L/12D 12D/12L 24D (5minL) 24D Light treatments Figure 1. Germination of Kalidium caspicum seeds in distilled water under various light conditions (24 hr light; 12 hr light/12 hr darkness; 12 hr darkness/12 hr light; 24 hr darkness, including 5 min light irradiated after 12 hr darkness; 24 hr darkness) at 25°C. Values at each light treatment having the same letter are not signifi cantly different (P> 0.05), Tukey’s test.

284 GERMINATION OF KALIDIUM CASPICUM SEEDS

Effect of temperature and salinity on germination A two-way ANOVA indicated significant individual effects of salinity, temperature and their interaction on germination percentage and on the rate of germination of K. caspicum seeds. Germination was higher in distilled water than in any of the salinity concentrations higher than 50mmol.L-1. As salinity levels increased, there was a gradual decrease in seed germination, which varied with change in temperature. Maximum germination under saline conditions were at 25 and 30°C. Seed germination at 20°C was comparatively lower than it was at the optimum temperature. Lower (10°C and 15°C) and higher (35°C) temperatures substantially inhibited germination at all salinities, and the lowest germination percentage was at 10°C (figure 2).

100 NaCl (mmol.L-1) 10°C 15°C 80 0 50 60 100 a 150 a 40 200 a

20 a b a a 0 c a

100 a a 20°C a 25°C a ab 80 bc b 60 c

40

20 c Germination (%) 0 d

100 a ab 30°C bc 35°C 80 c a a 60

40 d b 20 bc c 0

0246810 0246810 Time (d) Time (d) Figure 2. Cumulative mean germination percentage of Kalidium caspicum seeds in NaCl solutions incubated in 24 hr darkness. Values at each temperature having the same letter are not signifi cantly different (P> 0.05), Tukey’s test.

Speed of germination was affected by temperature when imbibed in both saline and non-saline conditions. At optimum temperatures, final germination in distilled water took 4 d and in saline solutions it took 6 to 10 d (figure 2). Germination rate was higher in distilled water than in saline solutions, and NaCl slowed rate of germination. Temperature also influenced germination rate. At 10, 15, 20 and 35°C, germination was slower than it was at 25 or 30°C (figure 3).

285 L. WANG, D.Y. ZHANG, Z.Y. HUANG AND C.Y. TIAN

100 10°C 15°C 80 20°C 25°C 60 30°C 35°C 40

20 Germination index (Gi) 0

050100150200

NaCl (mmol.L-1) Figure 3. Germination rate of Kalidium caspicum seeds in NaCl solutions at various temperatures. The regression curve for seed germination percentage at different salt concentrations indicated that the critical salinity tolerance of seed germination of K. caspicum was 198mmol.L-1 NaCl and the ultimate salinity tolerance (no germination) was 278 mmol. L-1 NaCl (figure 4). 100

80

60

40 Germination (%) 20 y = -0.0015x2+ 0.0634x + 96.114 R2 = 0.8526 0 0 100 200 300 NaCl (mmol.L-1) Figure 4. Regression curve of the seed germination percentage of Kalidium caspicum in NaCl solutions at optimum temperature.

Recovery test The recovery percentage increased progressively as NaCl pretreatment concentrations increased at the higher saline concentrations, (i.e., 100 to 200mmol.L-1 NaCl), the recovery percentage was significantly higher than it was in 0 to 50mmol.L-1 NaCl. Temperature also influenced recovery percentage: At 10, 15 and 35°C, recovery percentage was low in comparison to other temperatures. Recovery percentage of seeds pretreated with 200mmol.L-1 NaCl was 98.2 at 25°C. However, recovery percentage of seeds pretreated with the same saline concentration was 7.1 at 10°C (table 1).More than 91% of the seeds of K. caspicum germinated after ungerminated seeds were transferred to distilled water at 10, 15, 20, 25 or 30°C for five days and were subsequently transferred to 25°C for another five days. Final germination varied from 41% at 150mmol.L-1 NaCl to 85% at 200mmol.L-1 NaCl, after un-germinated seeds in distilled water at 35°C for five days were subsequently transferred to 25°C for another five days (figure 5). However, TTC test indicated seeds that still did not germinate in the recovery test were still viable.

286 GERMINATION OF KALIDIUM CASPICUM SEEDS

Table 1. The recovery percentage (mean ± s.e.) of Kalidium caspicum seeds after they were transferred to distilled water from NaCl solutions at various temperatures.

NaCl 10°C15°C20°C25°C30°C35°C (mmol.L-1)

0 6.1 ± 2.0 16.2 ± 4.1 8.3 ± 8.3 25.0 ± 25.0 0.0 ± 0.0 2.8 ± 2.8

50 2.0 ± 1.2 25.0 ± 9.7 90.0 ± 10.0 0.0 ± 0.0 29.2 ± 17.2 0.0 ± 0.0

100 9.0 ± 1.9 42.8 ± 3.6 97.2 ± 2.8 87.5 ± 7.2 87.5 ± 12.5 8.9 ± 1.0

150 4.2 ± 1.8 53.0 ± 6.5 97.5 ± 1.5 86.3 ± 8.0 92.3 ± 4.5 23.7 ± 2.4

200 7.1 ± 3.4 60.8 ± 4.3 92.7 ± 4.4 98.2 ± 1.8 91.5 ± 3.2 81.0 ± 4.9

10oC 15oC a aa a a a a 100 aa a

80

60

40

20

0 a a 20oC a 25oC 100 a a a a a a a

80

60

40

20 Germination (%)

0 a a 30oC Germination First recovery 35oC 100 a a a Second recovery a ab ab 80 ab

60 b 40

20

0 0 50 100 150 200 0 50 100 150 200 NaCl (mmol.L-1) NaCl (mmol.L-1) Figure 5. Seed germination, fi rst germination recovery and second germination recovery of Kalidium caspicum in NaCl solutions at various temperatures. Values at each temperature having the same letter are not signifi cantly different (P> 0.05), Tukey’s test.

287 L. WANG, D.Y. ZHANG, Z.Y. HUANG AND C.Y. TIAN

Discussion

Salt deserts show high levels of salinity and unpredictability of seasonal and annual conditions (Khan et al., 2001, 2002; Song et al., 2005). Nevertheless, seeds react to a number of environmental signals and tend to germinate when these signals provide indication of favourable conditions for seedling establishment and completion of the life cycle (Casal and Sánchez, 1998). For example, seeds of the halophyte shrub Halocnemum strobilaceum do not germinate until the salt is diluted by water from melting snow or until precipitation, temperature and light are not limiting for germination (Qu et al., 2008b). Seeds of K. caspicum germinated up to 87% if 24 hr dark and 89% if exposed to 24 hr darkness (with 5 min light irradiated after 12 hr). This indicates that this species germinated in the dark although short periods of illuminations do not interfere with the germination, because germination is only affected by darkness during the initial stage of germination. Germination was 65% if exposed to 12 hr dark followed by 12 hr light after planting; for seeds planted and exposed to 12 hr light followed by 12 hr dark, germination was only 27%. This means that seeds which are distributed on the soil surface and imbibed in water during the day may germinate poorly. Seeds of K. caspicum germinated to above 90% at temperatures between 20 and 30°C and germinated poorly at the extreme temperatures in distilled water in darkness, similar to those of several Xinjiang halophytic species (Song et al., 2006; Li and Zhang, 2007). It is possible that this is an adaptive strategy for seed germination in temperate inland deserts. In the present study, germination of seeds of K. caspicum was inhibited when imbibed in saline solutions. When ungerminated seeds, however, were transferred to distilled water for five days and the remaining un-germinated seeds that had been incubated in distilled water at 10 to 35°C were transferred to 25°C for another five days, different NaCl pretreatments had no adverse effect on final germination percentage except at 35°C. The result is similar to many halophytes, such as Salicornia europaea (Keiffer and Ungar, 1997), Aeluropus lagopoides (Gulzar and Khan, 2001), Limonium stocksii (Zia and Khan, 2004). The critical value of salinity tolerance of seed germination of K. caspicum is 198mmol.L-1 NaCl, and the ultimate value of salinity tolerance is 278mmol. L-1 NaCl. This indicates that K. caspicum seeds have a low level of salinity tolerance, but when transferred to optimum conditions, can recover and still germinate. At higher temperature (35°C), seeds did not lose viability and entered second dormancy. Seeds of K. caspicum may be seen as adopting a "cautious" germination strategy to avoid injury from salt. Seeds prevented from germination by previous exposure to hypersaline soil water were able to recover and germinate completely in distilled water. If recovery does not occur, ungerminated seeds may contribute to the seed bank (Li and Zhang, 2007). Tobe et al. (2000) reported that final germination percentage of seeds of K. caspicum did not differ significantly between treatments in light and in darkness at 15, 20, 25, 30°C. However, their light treatment was 12 h dark/12 h light. Qu et al. (2008a) reported that germination was significantly influenced by light – their light treatment was constant light and constant dark. According to our experimental results, different light conditions

288 GERMINATION OF KALIDIUM CASPICUM SEEDS resulted in different germination. Li and Zhang (2007) reported that the optimum temperature of K. caspicum was between 20 and 30°C, but this was based on germination in distilled water. However, when the salinity is between 100 and 200mmol.L-1 NaCl, the optimum temperature is between 25 and 30°C. Results here indicate that the ultimate value of salinity tolerance of seed germination of K. caspicum is 278mmol.L-1 NaCl which this is compatible with the results of Li and Zhang (less than 0.3 mol/L NaCl inhibited germination absolutely). Qu et al. (2008a) reported that seed germination percentages in NaCl solutions plus those that germinated after transferred to distilled water were no difference from those in the distilled water control. Our results confirm this under different constant temperatures. In conclusion, constant light and the initial irradiation restricted the germination of seeds of K. caspicum. The optimum temperature for germination was between 25 and 30°C. The ultimate salinity tolerance for seed germination of K. caspicum is 278mmol.L-1 NaCl, and seeds did not suffer ion toxicity after imbibition in NaCl. Irradiation, unfavourable temperatures, and high salt concentrations in the soil all prevent seed germination.

Acknowledgements

We thank Professor Carol Baskin and Jerry Baskin for their critical reading and revision of the manuscript. This study was funded by Science and Technology Key Project of the Xinjiang Uygur Autonomous Region (20050302) and "11.5" Momentous Special Project of the Xinjiang Uygur Autonomous Region (200733144-1).

References

Bao, S.D. (2000). Soil chemistry and agriculture analysis. China Agriculture Press, Beijing. Baskin, C.C. and Baskin, J.M. (1989). Role of temperature in regulating timing of germination in soil seed reserves of Thlaspi arvense L. Weed Research, 29, 317-326. Baskin, C.C., Baskin, J.M. and Chester, E.W. (1998). Effect of seasonal temperature changes on germination responses of buried seeds of Agalinis fasciculata (Scrophulariaceae), and a comparison with 12 other summer annuals native to eastern North America. Plant Species Biology, 13, 77-84. Baskin, C.C. and Baskin, J.M. (1998). Seeds: ecology, biogeography, and evolution of dormancy and germination. Academic Press, San Diego. Batlla, D., Nicoletta, M. and Benech-arnold, R. (2007). Sensitivity of Polygonum aviculare seeds to light as affected by soil moisture conditions. Annals of Botany, 99, 915-924. Casal, J.J. and Sánchez, R.A. (1998). Phytochromes and seed germination. Seed Science Research, 8, 317-329. Gul, B. and Weber, D.J. (1999). Effect of salinity, light, and temperature on germination in Allenrolfea occicentalis. Canadian Journal of Botany, 77, 240-246. Gulzar, S. and Khan, M.A. (2001). Seed Germination of a halophytic grass Aeluropus lagopoides. Annals of Botany, 87, 319-324. Huang, Z.Y., Zhang, X.S., Zheng, G.H. and Gutterman, Y. (2003). Influence of light, temperature, salinity and storage on seed germination of Haloxylon ammodendron. Journal of Arid Environments, 55, 453-464. Keiffer, C.H. and Ungar, I.A. (1997). The effect of extended exposure to hypersaline conditions on the germination of five inland halophyte species. American Journal of Botany, 84, 104-111. Khan, M.A. and Ungar, I.A. (1997). Effect of thermoperiod on recovery of seed germination of halophytes from saline conditions. American Journal of Botany, 84, 279-283.

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Khan, M.A. and Ungar, I.A. (1998). Germination of salt tolerant shrub Suaeda fruticosa from Pakistan: salinity and temperature responses. Seed Science and Technology, 26, 657-667. Khan, M.A., Gul, B. and Weber, D.J. (2001). Seed germination characteristics of Halogeton glomeratus. Canadian Journal of Botany, 79, 1189-1194. Khan, M.A., Gul, B. and Weber, D.J. (2002). Seed germination in the Great Basin halophyte salsola iberica. Canadian Journal of Botany, 80, 650-655. Khan, M.A., Gul, B. and Weber, D.J. (2004). Action of plant growth regulators and salinity on seed germination of Ceratoides lanata. Canadian Journal of Botany, 82, 37-42. Li, L. and Zhang, X.M. (2007). Germination strategies of two halophytes in salt desert of northwestern China. Science in China (Earth Sciences), 50, 115-121. Merritt, D.J., Kristiansen, M., Flematti, G.R., Turner, S.R. and Ghisalberti, E.L. (2006). Effects of a butenolide present in smoke on light-mediated germination of Australian Asteraceae. Seed Science Research, 16, 29- 35. Qu, X.X., Baskin, J.M., Wang, L. and Huang, Z.Y. (2008a). Effect of cold stratification, temperature, light and salinity on seed germination and radicle growth of the desert halophyte shrub, Kalidium caspicum. Plant Growth Regulation, 54, 241-248. Qu, X.X., Huang, Z.Y., Baskin, J.M. and Baskin, C.C. (2008b). Effect of temperature, light and salinity on seed germination and radicle growth of the geographically widespread halophyte shrub Halocnemum strobilaceum. Annals of Botany, 101, 293-299. Song, J., Feng, G., Tian, C.Y. and Zhang, F.S. (2005). Strategies for adaptation of Suaeda physophora, Haloxylon ammodendron and Haloxylon persicum to a saline environment during seed-germination stage. Annals of Botany, 96, 399-405. Song, J., Feng, G. and Zhang, F.S. (2006). Salinity and temperature effects on germination for three salt-resistant euhalophytes, Halostachys caspica, Kalidium foliatum and Halocnemum strobilaceum. Plant and Soil, 279, 201-207. Tobe, K., Li, X. and Omasa, K. (2000). Seed germination and radicle growth of a halophyte, Kalidium caspicum (Chenopodiaceae). Annals of Botany, 85, 391-396. Tobe, K., Li, X. and Omasa, K. (2002). Effects of sodium, magnesium and calcium salts on seed germination and radicle survival of a halophyte, Kalidium caspicum (Chenopodiaceae). Australian Journal of Botany, 50, 163-169. Zhu, G.L., Mosyakin, S.L. and Steven, E.C. (2003). Flora of China, 5, 351-414. Science press, Beijing. Zia, S. and Khan, M.A. (2004). Effect of light, salinity, and temperature on seed germination of Limonium stocksii. Canadian Journal of Botany, 82, 151-157.

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