Great Basin Naturalist
Volume 59 Number 2 Article 5
4-30-1999
Effect of salinity on seed germination of Triglochin maritima under various temperature regimes
M. Ajmal Khan Ohio University, Athens, Ohio
Irwin A. Ungar Ohio University, Athens, Ohio
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Recommended Citation Khan, M. Ajmal and Ungar, Irwin A. (1999) "Effect of salinity on seed germination of Triglochin maritima under various temperature regimes," Great Basin Naturalist: Vol. 59 : No. 2 , Article 5. Available at: https://scholarsarchive.byu.edu/gbn/vol59/iss2/5
This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Grt: EFFECT OF SALI lIT ON SEED GERMI ATIO . OF TRIGLOCHIN MARITIMA UNDER VARIOUS TEMPERATURE REGIMES M. Ajmal Khan 1,2and Irwin A. Ungar1•3 ABSTIlA(:1~-Triglochin maritima L. (anuw grass), an herbaceous perennial in the family }uncaginaceae, is widely dis trihuted in inland and (,;oastllJ salt marshes of North America Tfiglochin maritima seeds from a population gro~ing in a salt marsh at Faust, Utah, were germinated at 4 temperature regimes (12-h night!12.h day, 5-15°C, 5-25°C, lO-20°C, and 15-25°C) and 5 salinities (0, 100, 200, 300, 400, and 500 mol m-3 NaCl) to determine optimal conditions for germi nation and level of salt tolerance. Ungerminated seeds were returned to distilled waler after 20 d to determine whether s~eds could recover fi'om salinity treatments. Maximum germination occurred in distilled water, and increases in NaC! eOl1eentr Key wonls: Triglochin lOmitima, halophyte. recovery, seed germination, theNl'loperWd. Utah. TriglnchinmlJlitima L. (Juncaginaceae), com· French population of T. maritima had a pri manly known as arrow grass, is a clonal peren mary morpho-physiological dormancy and nial that can form regular clumps up to 2 m that seeds of T. ma1'itima were more dormant across and 60 em high (Davy and Bishop 1991). than T. palustris, probably because of the more Common in saline habitats. particularly coastal resistant sclerenchyma tissue in the pericarp marshes on rocky shores in temperate, subarc of the fanner. The 2 basic types of dormancy tic, and arctic regions, it also extends southward that seeds develop are due either to some to the subtropics (Davy and Bishop 1991). morphological or biochemical characteristics Triglochin maritima is distributed in inland of the diaspore that produce a primary dor and coastal brackish and freshwater marshes mancy (fruit or seed) or to an environmental and bogs of North America (Sheiller and Skog factor that induces seeds into a secondary dor 1978). Ungar (1974) surveyed a Triglnchin mario mancy (Bewley and Black 1982). Bioet (1961a, ti.oo community located at Park County, Col· 1961b) reported that T. 700ritima had a sec orado, and reported that T. maritima grew in ondary dormancy induced by darlmess, which almost pure stands in a wetter area with soil in nature is probably triggered by the burial of salinity ranging from 0.5% to 1% (85-170 mol seeds in the soil. m-3). Triglochin maritima was also found gro\.,,~ Germination responses of seeds of T. mar ing in salt marshes at the Fish Springs research itima populations from North America have site, Juab County, Utah, in an Eleocharis not been previously investigated, and one of meadow community where salinity averaged the goals of this investigation was to deter 0.5% total salts (Bolen 1964). mine if responses to environmental variables Germination of halophytes is affected by differ from populations studied from Europe temperature and soil salinity content, and and related species from Mrica. Naidoo and seeds are characterized by varying types and Naicker (1992) studied the effect oflight, tem degrees ofdormancy (Binet 1965, 1968, Ungar perature. and salinity on the germination of T. 1991). Binet (1959) "eported that seeds from a bulbosa and T. slIiata populations from South Ilkp:u1J'\C'\t orEm·;mOOlClIbl lIrod P(.ntlJinloj1y, Ohio T.Jnh~r>;;t)·, Atheros. OH 4.5iOl·2919l,;SA. 'Pt"t'l'>;lJ.cnt ucldJ"",,,, lk"urtrnC\l1 or 1k>t.V1~, L" nivcnityor Kar""hi, Kilnx1ti·75270. P..kU-t:In. Jolrrr.s\'lC",dilll: 3\1tl_. 144 1999] GERMINATION OF TRIGWCHIN MARITIMA 145 Aliica and determined that both species have detelmines if a population will survive to a light requirement for gennination and reproductive maturity. Each species has very achieve higher germination at a warmer tem specific germination requirements. and its re perature regime (20-30°C). Germination was sponse to stress varies from that of other highest in distilled water and decreased signif species. For this reason it is important to de icantly with an increase in salinity up to 500 termine the range of tolerance to salinity and mol m-3. Transfer of ungerminated, salt temperature regime effects on germination. treated seeds to distilled water stimulated ger The effects of salinity and temperature regime mination more in T strota than in T bulbosa. on germination and recovery responses of T. The interaction between salinity and tempera 1TI.aritima were studied to determine their in ture on germination has been the subject of dividual effects and any interaction between investigation (Khan and Ungar 1984, Gutter these factors on seed germination. We also de man 1986, Khan and Weber 1986, Khan et aI. termined if salinity and temperature regime 1987, Badger and Ungar 1989, Khan 1991, interact in their effects on recovery germination Khan and Rizvi 1994) because it plays a signif ofseeds initially exposed to saline conditions. icant role in determining the timing of germi nation. However, no data are available con MATERIALS AND METHODS cerning the effect of the interaction between different temperature regimes and salinity on We collected TIiglochin nwritinw L seeds seed germination of North American popula during August 1995 from a salt marsh situated tions of T. maritima. These 2 environmental 30 mi south of the Great Salt Lake, at Faust, factors playa significant role in determining Utah. Seeds were separated from the inflores whether plants can successfully establisb in cence and bronght to Ohio University where saline habitats because they interact in deter they were stored at 4°C. Preliminary tests mining if seeds germinate or remain dormant indicated the seeds were viable and germina in the seed bank (Ungar 1995). One ofthe pur tion experiments were initiated in September poses of this investigation was to determine 1995 in 50 x 9-mm (Gelman No. 7232) tight how the germination response of T. maritima fitting plastic petri dishes with 5 ml of test to temperature and salinity may affect its estab solLltion. Each dish, containing 25 seeds that lishment ill salt marsh habitats. were surface sterilized with the fungicide Recovery germination of seeds in fresh Phygon, was placed in a 10-cm-diarneter plas water after they were exposed to saline condi tic petri dish as an added precantion against tions has been investigated (Ungar 1962, 1978, water loss by evaporation. Four petri dishes Barbour 1970, Parham 1970, Macke and Ungar containing 25 seeds each were used as repli 1971, Seneca and Cooper 1971, Woodell 1985, cates for each salinity and temperature treat Keiffer and Ungar 1995) to determine if seeds ment; seeds were considered to be germinated can remain viable after being exposed to with the emergence ofthe radicle. hypersaline conditions, but no similar data are To determine the effect of temperature on available for T nwritinw seeds. The ability of germination, we used regimes of 5-15°C, seeds to germinate after exposure to hyper 5-25°C, 10-20°C, and 15-25°C. We used a saline conditions plays a significant role in the 24-h cycle, where the higher temperature (15, establishment ofhalophyte populations. Seeds 20, or 25°C) coincided with the 12-h liF;ht of glycophytes cannot germinate after expo period (Sylvania cool white flnorescent lamps, sure to salt stress, while halophytes show a 25 !Lmol m-2 s-l, 400-750 nm) and the lower range of responses from partial to complete temperature (5, 10, or 15°C) coincided with germination recovery when salinity stress is the 12-h dark period. Seeds were germinated alleviated (Woodell 1985, Ungar 1991). in distilled water, 100, 200, 300, 400, and 500 This study was initiated to obtain a better molm-3 NaCl solutions in each of the temper understanding ofgermination requirements of ature regimes. and germination was recorded seeds of a population of T maritima from the every other day for 20 d. After 20 d we trans Great Salt Lake region of Utah. Initial estab ferred ungerminated seeds from the NaCl lishment of species in salt marsh habitats is treatments to distilled water and a tempera related to germination response of seeds to ture regime of5-25°C to determine the recov salinity and temperature regime and usually ery germination, which was also recorded at 146 GHEAT BASIN NATURALIST [Volume 59 TABI,g 1. Results of a 2-way ANOYA offinal percent germination of Trigf.ochin maritima in different salinity and tem perature treatments. Sum of Meml SignifIcance Source ofvariation squares df square F ofF Temperature 10327.3 3 3442.4 72.4 0.0001 Salinity 17729.3 5 3545.9 74.6 O.OOOJ Temperature x salinity 7702.7 15 1513.5 10.8 0.0001 2-d intervals for 20 d. Rate of germination was 100 1------,=====]1 estimated by using a modified Timson index of _ 10-20°C germination velocity (TI = LG/t), where G is mIlmll 15-25°C the number of seeds germinating at 2-d inter ~ 5_25°C 80 ~ 5_15°C vals and t is the total germination period (Khan ,md Ungar 1984). The maximnm value ~ possible using this index with OUf data was 50 ~ 80 *c (i.e., 1000/20), and the higher the value, the g ~ more rapid the rate ofgermination. c E Germination data were transformed (arcsine) " 40 before statistical analysis and data were ana • lyzed with a 2-way ANOVA using SPSS for " Windows, release 6.1 (SPSS Inc. 1994). 20 RESULTS 0-1..-- DiUerent temperattire regimes, salinity, o 100 200 300 400 500 3 and their interaction significantly (P < 0.0001) NaC! (mol m- ) affected the !lnal percent germination of T. maritima seeds (Table 1). Germination of T. li'ig. I Percent germination of 1Hgl.ochin nw.ritima seeds maritima was highest in distilled water and at in 0, 100,200,300, 400, and 500 mol m-J NaCI at temper ature regimes of5-LljoC, 5-2,s°C, lO-20°C, and 15-25°C. a regime with low night (5°C) and high day (25°C) temperatures (Fig. i). Maximum germi nation percentages were achieved in 12 d in all treatments. Germination of seeds decreased temperature regimes of 10--20°C ,md 15-25°C, with increases in salinity; few seeds germi the rate of germination was similar in the con nated at salt concentrations higher than 300 trols, but the interaction caused by the addi mol m-3 Nael (Fig. 1). Variation in tempera tion of NaCI to the medium adversely affected ture regime significantly affected seed germi the germination rate at 1O-20°C (Tables 2, 3). nation under both saline and non-saline condi Mter 20 d of NaC! treatmeut, seeds were tions. In fact, there was less than 10% germi transferred to distilled water, where there was nation at the 5-15°C temperature regime in less than 25% recovery germination in the the control and all salinity treatments (Fig. 1). 10-20°C temperature regime at all NaCI con At other temperature regimes there was a sig centratious (Fig. 2). At 15-25°C and 5-25°C nificant inhibitory interaction between tem the final germination percentages increased to perature and salinity on final germination per more than 50% at 500 mol m-3 NaC!. Recov centages (Table 1, Fig. i). ery at the highest salinity concentration (500 Different temperature regimes, salinity, mol m-3) was lower than that in the 400 mol and their interaction signi!lcantly (P < 0.0001) m-3 NaCl treatment, which did not diller sig aflected the rate of germination of T. maritima nificantly from the control at 5-25°C (Fig. 2). seeds as determined from the Timson index of Ungerminated seeds from the 5-15°C temper germination velocity (Tables 2, 3). The rate of ature regime were transferred to 5-25°C after germination, calculated using a modified Tim 20 d and germination increased, but germina son index of germination velocity, was lowest tion was significantly lower than for those seeds iu 5-1,5°C aud highest in 5_25°C (Table 2). At that initially germinated at 5-25°C (Fig. 2). 1999] GERMINATION OF TRlGLOCHIN MARITIMA 147 TABLE 2. Index ofgermination velocity, using a modified TlJ1lson index (Khan and Ungar 1984) to estimate rate ofger mination of Tnglochin maritima. Temperature regime (0G) NaCI (mol m-') 10-20 15-25 5-25 5-15 0 15.7± 2.3 17.8±3.4 24.1± 3.3 0.7± 0.7 100 4.2 ± 2.3 12.4 ± 2.4 16.4± 0.8 0 200 2.7± 0.8 6.6 ± 1.7 9.6 ± 1.2 0.4 ± 0.3 300 1.2 ± 0.5 5.0 ± 1.2 4.5 + 0.4 O.l± 0.1 400 0 1.7 ± 0.7 0.5 ± 0.2 0 500 0 0 0 0 TABLE 3. Results ofa 2-way ANOVA, using data from the Timson index ofgermination velocity to estimate rate ofger· mination ofTriglochin maritima at different salinities and temperatures. Sum of Mean SigniUc.ml.'e Source ofvariation squares df square F ofF Temperature HlSA 3 372.8 51.2 0.0001 Salinity 2434.5 5 486.9 66.9 0.0001 Temperature x salinity 1016.9 15 67.8 9.3 0.0001 Recovery germination percentages increased the dark (Parham 1970). Our results indicate with an increase in salinity concentration (Fig. that seeds of this Utah population were not 3). At a temperature regime of 1O-20"C, a dormant and that germination was inhibited maximum of 20% recovery germination was by high salinities and low day temperatures. obtained in 500 mol m-3 NaCI, but seeds We determined that Triglochin maritima seeds treated with 400 mol m-3 NaCI at 5-25"C had had their highest germination percentages in 72% recovery (Fig. 3). distilled water and a progressive decline in germination with increases in salinity. SimiJar DISCUSSION results were found in populations from Europe (Binet 1960, 1965, Pigott 1969, Latschert 1970). l1iglochin maritima germination is most Our results agree with those of Binet (1965), probably regulated through variation in soil who determined that germination in saline salinity and temperature regime under natural media ofseeds from a French population ofT conditions. When soil salinity is beyond the maritima was greatly facilitated by alternating levels at which seeds can germinate, seeds may temperature regimes of5-25°C, which can sub die or remain dormant in the soil seed banle stitute substantially for the light requirement Seed germination can then take place at a Likewise, germination of the related species later time in the gro,....ing season or in another Triglochin bulbosa and T striata was also high year after salt stress has been alleviated (Ungar est in non~saUne controls and decreased sig 1995). Bolen (1964) and Ungar (1974) reported nificantly with an increase in salinity up to 500 that T maritima was found growing in com mol m-3 (Naidoo and Naicker 1992). Higher munities with moderate salinity, 0.5-1.0% total day temperatures were more stimulating for salts (85-170 mol m-3). We determined that germination compared to lower thermoperi seeds from the Utah population requiTed low ods in all of these species of Triglochin. Simi soil salinity and a temperature regime with lar promotive effects ofhigh daytime tempera low night (5°C) and high day temperatures tures 00 gennination also were found in other (25°C) to promote maximum gemrination. perennial halophytes such as Cressa cretica Binet (1959) reported that freshly collected T (Khan 1991), Atriplex griffithii (Khan and Rizvi maritima seeds enclosed by the pericarp had 1994), Salicomia pacifica var. utahensis (Khan an innate donnancy and poor germination in and Weber 1986), Halopymm mUCl'Onatum 148 GREAT BASIN NATlJHALIST [Volume 59 100 T 9O-j 80 10-20 DC 15-25 DC ?j 70 ~ 0 60 0 50 - -•0 40 0-0 •••• • • ••• E -.~- 3 ~ 30 - 0 mol m- • 20 I _ 100 mol m-l l '" 10 ---4---- 200 mol m- 0 ----T-- 300 mol m" l 100 ~ j------il-~.... 400 mol m- --.- 500 mol m-l 90 5-25°C 80 70 - ~ ---.-----.------• • .---+--. -0 -'"'0 60 Q 50 - -•0 40 - E ~ 30 • 20 '" 10 0 -T ·,--r-,--T",·,-T-,-·-r...... --r- 20 22 24 26 28 30 32 34 36 38 40 20 22 24 26 28 30 32 34 36 38 40 Days Days Fig. 2. Percent germination of'Ihglochin maritima seeds after being transferred [rom 0,100,200,300,400, and ,500 mol m-:3 NaC,l at temperature regimes of5-15°C, .5_2.5°C, lO-20°C, and 15-25°C. (Noor and Khan 1995), and Chrysothamnus 500 mol m-3 NaC] was temperature depen nauseOSU8 (Khan et a1. 1987). dent. Keiffer and Ungar (1995) exposed seeds Seeds of Triglochin maritima from the Utah of 5 halophytes (Aldpiex prostrata, Hordeum population, when transferred to distilled water jubatum, SaUcornia europaea, Spergularia after a 20-d treatment at various salinity con marina, and Suaeda calceolijonnis) to salinity centrations, responded differentially under treatments for 2 yr and determined their re different temperature regimes. There was lit covery responses when transferred to distilled tle recovery (20%) with the 10-20°C tempera water. They used the Woodell (1985) classifica ture regime in non-saline controls, but at tion system and placed Atriplex prostrata seeds 5-25°C seeds incubated previously at 400 mol in Type 1 (recovery inhibited by high salinity), m-''3 NaCI had about 72% recovery. It seems Hordeum jl1hatl1m and Spergularia marina in that recovery germination of T. rnaritima is Type 2 (recovery equal to original controls), and temperature dependent. Binet (1961b) deter Salicornia europaea and Suaeda calceolijormis mined that seeds of T. nwritirna from a French in Type 3 (salt stimulated, recovery greater coastal population had a stratification and light than controls). Our data from the 500 mol m-3 requirement, and when immersed in seawater NaCI treatment indicate that T. maritima at 3°C lor 60-80 d, they were capable of ger recovery germination could be classified in minating subsequently in freshwater upon 'lypc 1 (10-20°C) or Type 2 (15-25'C), depend transfer to 25°C in the light or dark. Seeds ing on the temperature regime used in the from the Utah population did not require recovery germination experiment. Seeds ex stratification and were not dormant. \\Toodell posed to 5-15'C in all salinity treatments had (1985) inclnded T maritima in the group of low recovery germination percentages. coastal species whose subsequent germination Triglochin maritima seeds had maximum is stimulated by exposure to high salinity, al germination at a 5-25°C temperature regime though the germination percentages he re at all NaCI concentrations tested. Few seeds corded were low. Our results indicate the germinated at the 5-15°C in non-saline con recovery germination response of T. l1Ulritil1Ul trols. Inability to germinate at Imv day tem seeds in distilled water after 20 d exposure to perature in the laboratory indicates that a 1999] GEHr>.HKATION OF TRlCLOCHIN MARITIMA 149 100 -,------,------ 80 80 ~-. -. .. . . is 40 • •• '"...... " ...... c 20 • • • • • E ...... Cl.. a 100 - -r-, I I 5-25°C a 2 4 6 6 10 12 14 16 18 20 60 • •• 60 • • • •• • ...... Omolm' __ 100 mol m-' g 40 ,...... , ...- 2OOmolm' ...... to ... -'P- 300 mol ..,-' .--..c ...... - 400 mol rn~ E ...... SoOO mol m" Cl.. ~~~~ I ·-~I~- o 2 4 6 8 10 12 14 16 18 20 Days Fig. 3. Perccnt rC(,'{lVery germination in fioeshwater of ungerminated Triglo<:hin maritima seeds initially exposed 10 0, 100,200, ,300, 400, ond 500 mol m-:l NaCI at temperature rep;imes of5-25°C, ,lO-20°C, and L,-2.,OC. threshold of nigher day temperatures is neces germination and recovery of seeds of r mar sary to stimulate germination under field con itima from hypersaline conditions. Seeds were ditions, A combination of reduced salinity and not dormant but did have speciHc temperature high daytime temperatures stimulates genni requirements for maximum gennination. nation and determines the sites along salinity gradients where germination and establish ACKNOWLEOCMENTS ment of 1: maritima can occur. Because soil .\ BEWLI:;Y. J.D., AND M. BLACK. 1982. Physiology and bio KHAN, M.A., N. SANKHLA, D.J. WEBER, AND E.D. chemistry ofseeds. Springer-Verlag, Berlin. 375 pp. McARTHUR. 1987. Seed germination characteristics B1Ntrr, P. 1959. Dormances primaire et secondaire des ofChrysothamnw nauseosw ssp. oiridult£s (Astereae, semenees de Trigloc1JJn maritimum L.: action du froid Asteraceae). Great Basin Naturalist 47:220-226. et de la lumiere. Bulletin de 1a Societe Linneenne UJTsCHEJIT, W. 1970. Keimung. li'anspi.ration. Wasser· und de Norrnanrue (Caeo), ge series, 10:131-142. loneaufnhame bei Glycopbyten nnd Halophyten. _--:,," 1960. Rapports entre reau de mer et la germina Oecologia Plaotarum 5Jl87--300. tion des semences de Trigltxhin marUimum L. Bul MACKE, A., AND l.A.. UNCAR. 1971. The effect of sali.nity letin de la Societe Unneenne de Normandie (Caeo), on germination and early growtb of puccinellia nut lOe series, 1:117-132. talUana. Canadian Journal ofBotany 49:515-520. . 1961a. Action d'une brusque modification de NAIDOO, G., AND K. NAlCKER. 1992. Seed germination in --p-ression osmotique et de pH sur 1a germination des the coastal halophytes Triglochin buJhosa and Triglo semences de Triglochin mnritimum L Bulletin de 1a chin striata. Aquatic Botany 42:217-229. Societe Linneenne de Normandie (Caeo), lOe series, NooR, M., AND KHAN, M.A. 1995. Factors affecting germi 2,116-123. nation of summer and winter seeds of Halopymm ___.. 1961b. Acquisition de l'aptitude a germer en mucronatum under salt stress. Pages 51-58 in M.A. milieu sale par les semences de Triglochin mariti· Khan and I.A. Ungar, editors, Biology ofsalt tolerant mum L. Bulletin de la Societe Linoeenne de Nor plaots. Department of Botaoy, University of Karachi, mandie (Caen), JOe series, 2:124-128. PakisIan. _-::c' 1965. Action de divers rythmes tbermiques jour PARHAM, M.R. 1970. A comparative study ofmineral outri naliers sur la germination de semences de Triglochin tion of selected halophytes and glycophytes. Doc matitimum L. Bulletin de 1a Societe Linneenne de toral thesis, University ofEast Anglia. Nonnandie (Caen), tOe series, 6:99--102. PlGOTI, C.D. 1969. Influence of mineral nutrition on the _-::c' 1968. Donnances et aptitude a germer en milieu zonation offlowering plants in coastal marshes. Pages sale chez les halophytes. Bulletin de la Societe de 25-35 in LH. Rorison. editor, Ecological aspects of France Physiologic Vegetale 14:125-132. mineral nutrition jn plants. Symposia ofBritish Eco BOL£N, E.G. 1964. Plant ecology ofspring-fed salt marshes logical Society, 9. Blackwell Scientific Publications, ofwestern Utah. Ecological Monographs 34:143-166. Oxforo. DAw. A.J., AND C.R BISfIOP. 1991. Biological flora of the SENECA, E.D., AND A.W. CooPER. 1971. Germinatioo and British Isles No. 172. Journal ofEcology 79:531-555. seedling response to temperature, daylength, and GUlTERMAN, Y. 1986. In1Juem..'es of environmental factors salinity by Ammophila breviligulata from Michigan on germination and plant establishment in the Negev and North Carolina. Botanical Gazette 132:203-215. highlands of Israel. Pages 441--443 in P.J. Joss, P.W. SHELTLER, S.G., AND L.E. SKOG. 1978. A provisional check Lynch, and O.B. Williams, editors, Rangelands: a list of flora of North America (revised). Missouri resource unclel' siege. Australian Academy of Sci Botanical Carden. 199 pp. ence, Canberra. SPSS INC. 1994. SPSS: SPSS 6.1 for windows update. KEIFFER. C.w., AND LA. UNGAR. 1995. Germination re SPSS Inc., USA. 30 pp. sponses of halophyte seeds exposed to prolonged UNGAR. lA. 1962. Influence of salinity on seed germina hypersaline conditions. Pages 43-50 in M.A. Khan tion in succulent halophytes. Ecology 43:763-764. nod LA. UngaJ; editors. Biology of salt tolerant _--:::' ]974. Population dynamics of inland halophytic plants. Department of Botany. Universi.ty of Karachi, communities. Bulletin de la Societe Botanique de Pakistan. France 121:287-292. KHAN, M.A. 1991. Studies on germination ofCressa cretica. --oc' 1978. Halophyte seed germination. Botanical Pakistan Journal ofWeed Science Research 4:89-98. Review 44:233-263. KHAN, M.A., AN)) Y. RIZV[. 1994. Effect of salinity, temper _-.,•. 1991. Ecophy,jology ofvascula' halophytes. eRe ature, and growth regulators on the germination and Press, Boca Raton. FL. 209 pp. early seedling growth ofAtriplex grifJi:ihii var. stock _,.... 1995. Seed gennioalion and seed-ban.k ecology of sii. Canadian Journal ofBotany 72:475-479. halophytes. Pages 529-544 in J. Kigel and G. Gahh, KHAN, M.A., AND LA UNCAR. 1984. The effect of salinity editors, Seed development and germination. Marcel llnd temperdtw'e on the germination ofpolymoJ'pbic Dekker, New York. seeds and growth of Atrlplex triangularis Willd. WOODELL, S.R.J. 1985. Salinity and seed germination pat American Journal ofBotany 71:481-489. terns in coastal plants. Vegetatio 61:223-229. KHAN, M.A., AND D.J. WEBER. 1986. Factors influencing seed germination in Salicornia pacifica Val". uta-Mnsis. Received 10 February 1998 American Journal ofBotany 73:1163-1167. Accepted 14 ],dy 1998