Oecologia (1989) 78 : 559-564 Oecologia �9 Spfinger-Verlag 1989

Salinity studies with drought-resistant species of Sporobolus J .N . W o o d and D . F . G a f f

Botany Department, Monash University, Clayton 3168, Australia

Summary. Dry matter productivity under saline conditions was compared in 5 desiccation-tolerant "resurrection" grasses and one desiccation sensitive species, all in the genus Sporobolus. S. stapfianus was the most salt tolerant, requir- ing 215 mole NaC1 m -3 to reduce shoot dry matter incre- ments to 50% of increments in plants not treated with salt. (This was comparable to published values for the salt toler- ant grass Diplachnefusca.) S. lampranthus was salt sensitive, requiring 35 mol m -3 for 50% control yields. S. festivus, S. aff. fimbriatus, and the desiccation sensitive S. pyramida- lis was moderately tolerant (150 170 mol m-3). The moder- ate salt resistance of S. aff. fimbriatus was attributed mainly to exclusion of NaC1 by roots. Salt export through leaf surfaces was a minor factor. Half of the leaf mesophyll cells survived 50 min immersion in 200 tool NaC1 m -3. Plants of S. aff. fimbriatus and S. pyramidalis tolerated a broad range of soil pH. Plants of 4 desiccation tolerant Sporobolus species survived air-dryness following 3 weeks pretreatment with salinities up to 200 mol m-a.

Key words: Drought tolerance - pH tolerance - Poaceae - Resurrection grass - Salt tolerance - Sporobolus

Salinization of soil reduces the water potential of the soil and perturbs the water potential through the plant from roots to leaves, resulting in more negative potentials. The ability of shoots to survive low water potentials, then, is a factor contributing to the overall salt resistance of a plant, though clearly other attributes are also required, e.g. the ability of roots to exclude soil salt, the ability of shoots to export salt to the exterior, or the ability of cells to survive salt that reaches them. The present investigation examines the salt resistance of grass species in the genus Sporobolus. This genus is of particular interest since a few species are desiccation tolerant, i.e. their foliage survives air-drying (to water potentials of - 200 MPa and less), and they therefore have an abundance of one attribute required for salt resis- tance (Gaff and Ellis 1974; Gaff 1986). Also other species have been reported to possess salt glands (Liphschitz and Waisel 1974).

Mater ia l s and methods

Plants were grown in unheated glasshouses from the stock plants or caryopses originally collected from Africa. S. aff.

Offprint requests to: D.F. Gaff

firnbriatus (Gaff 239) and S. pellucidus Hochst. from Kenya, S. lampranthus Pilg., S. pyramidalis Beauv., S. festivus Hochst. and S. stapfianus Gandoger from southern Africa. All the species are desiccation tolerant "resurrection" grasses, except for S. pyramidaIis which has considerable drought resistance based on drought avoidance mechanisms (Gaff and Ellis 1974; Gaff 1986).

The Sporobolus spp. used here are sensitive to prolonged waterlogging and could not be cultivated in hydroponic systems. Plants consequently were transplanted into washed river sand, fine to medium-fine grade, in 150 mm black plastic pots, regularly flushed with 200 ml of appropriate treatment solutions to avoid excessive ion accumulation.

Plants were irrigated only with water for the first week, then irrigated weekly with half-strength Hoagland's solu- tion (Hoagland and Snyder 1933), for a minimum of two weeks before commencing salt treatments. Half-strength Hoagland's solution was incorporated in all salinized me- dia.

At the commencement of the trial, plants within each species were selected for similar size and age, then cut to a height of 3 cm.

Randomly selected pots were weighed during the week, so that transpiration and surface evaporation losses could be replaced by water. On the day before fresh salinized solution was applied each week, the previous salt solution was flushed out by two irrigations of 200 ml of water.

Salinity treatments was continued for six weeks (March 16th to April 27th, 1987). At the end of the trial foliage was again harvested to a height of 3 cm and oven- dried (65 to 70 ~ C, 48 h).

A pH growth trial was conducted on S. aff. fimbriatus and S. pyramidalis, the only species with sufficient plants available. Half-strength Hoagland's solutions were adjusted to required pH levels with either hydrochloric acid or sodi- um hydroxide (Vane model 203 electronic pH meter). The pH solutions were made up twice a week. Plants (9 repli- cates) were irrigated every two days with 20 ml of freshly prepared pH solution. The actual pit of the sand was tested periodically for each pH treatment.

The dry weights of harvested foliage were determined after 8 weeks (March 18th to May 13th, 1987) as described for the salinity growth trial.

Experiments on transpiration salt content, leaf salt ex- port and salt exclusion were run concurrently, over a four week period (July21st and August 18th, 1987), using S. aff. fimbriatus, under the procedures for irrigation and tran- spiration measurement described above. Total plant tran- spiration was assayed as weight loss from a sealed pot.

560

Viable leaf area was measured using a LiCor model LI-3000 portable area meter.

Harvested leaves were divided into juvenile and mature categories, for separate analysis. Juvenile leaves had yet to completely unroll and were partly enclosed in the sheath of the earlier leaf. The remainder of the foliage was classed as mature.

Plants of Sporobolus aff. fimbriatus were destructively analysed for their internal content of the major inorganic ions, chloride, sodium and potassium after i week and 4 weeks of salinity treatment.

Inorganic ions were extracted from 0.5 g finely ground dried material using a modified hot water method. Samples were heated with distilled-deionized water (25 ml), in a shaking-water bath (80 ~ C for 10 rain). Extraction was re- peated twice and the decanted supernatants bulked and fil- tered (Whatman's no. 1). Chloride was determined by the chromate titration method of Piper (1944). Sodium and potassium were determined by atomic absorption using a Varian Techtron, model AA-4 atomic absorption spectro- photometer. An airpropane flame with an oxidizing cone of 1.5 cm height was used, with a lamp current of 5 mA.

An equal volume of ionization suppressant solution was added to each sample solution and standard solution. This solution contained 10 g L -1 strontium (as SrC12-6H20) and 2 g L-1 caesium (as CsC1) to suppress interference, respectively, for calcium and magnesium, and for sodium and potassium. Salt exported onto the leaf surface was mea- sured by analysis of leaf washings (Liphschitz and Waisel 1974).

At the commencement of the experiment, the entire leaf surface was washed free of ions with distilled-deionized water. Separate plants were then given saline irrigation for either I week or 4 weeks, before the second leaf washing to collect surface ions. A modification of the technique of Boon and Allaway (1982) was used for the final leaf wash- ing. The washing solutions were analysed for chloride by chromate titration (Piper 1944) and for sodium and potassi- um by atomic absorption, as described.

Salt exclusion

Salt exclusion was extimated from the actual salt taken up by the plant, compared to the potential uptake, based on the quantity of water transpired and the salt concentra- tion applied to the roots. The calculations were corrected for the specific gravity of saline water at each concentration of NaC1. The maximum theoretical salt uptake was calcu- lated from the product of the total accumulative transpira- tion and the specific concentration of the applied solution, corrected for the specific gravity of the applied solution. The percentage salt exclusion was then calculated, by divid- ing the actual salt uptake by the theoretical maximum salt uptake.

The cellular salt tolerance was investigated for Sporobo- lus aff. fimbriatus, which had been irrigated only with half- strength Hoaglands solution.

Transverse sections were hand-cut from mature leaves approximately half-way along the leaf length. The sections were cut to a thickness of one layer of undamaged cells and were placed in saline half-strength Hoagland's solutions for 50 min. Cell survival was scored both before and after the salt treatment, based on vacuolar accumulation of neu-

tral red (0.03% solution at neutral pH, for I h and mounted in water).

In order to test the effects of internal salt on plant desic- cation tolerance, plants were irrigated with various concen- trations of NaC1 in half-strength Hoagland's solution for 3 weeks. Salt was then flushed from the sand by repeated excessive irrigations on 4 th Nov, after which plants were allowed to dehydrate to air-dryness (approx. I week). Plants were held air-dry for a further 3 weeks. Shoots were cut to 3 cm, watering was recommenced, and plants scored for growing shoots.

Results and discussion

Growth response to salinity

All of the tested species grew at the upper 250 mol m-3 NaC1 limit of salinity tested, although growth was reduced to only 28~42% of the control yield in all species at 250 mol m-3 NaC1 (Figs. 1-6). According to the classification of Greenway and Munns (1980), S. stapfianus lies at the lower tolerance range for halophytes; S. pyramidalis and S. festi- vus would be classed as tolerant nonhalophytes, bordering on being halophytes; S. aff. fimbriatus, S. peIlucidus and S. lampranthus would be tolerant, intermediate and sensitive nonhalophytes, respectively. Except for S. stapfianus, an initial yield reduction of 10-25% in the Sporobolus spp. occurred at lower salt concentrations than in the pasture species listed in Table 1. On the other hand, the four most tolerant Sporobolus spp. (S. stapfianus, S. pyramidalis, S. festivus and S. aff. fimbriatus) reached 50% of control yields at similar salt concentrations to those for known salt-toler- ant pasture species (Table 1). S. stapfianus is among the most tolerant group of the twelve species compared in Ta- ble 1, although S. stapfianus was not collected from a saline environment. However, plants of S. stapfianus are relatively low-growing and their dry matter yields are not great. S. aff. fimbriatus and S. pyramidalis produce larger biomasses (Table 2). The potential of S. aff. fimbriatus, S. pyramidalis and S. pellucidus for cultivation as pasture grasses, under saline conditions, warrants further investigation.

Response to pH

The sand pH was found to drift slightly towards neutral pH, drifts up to 1.2 pH values were measured for the pH 2 and pH 10 treatments. Despite apparent optima at pH 7, there was no significant difference in yield between pH treatments for either S. aff. fimbriatus or S. pyramidalis (Fig. 7). Other Sporobolus spp. are known to be remarkably tolerant of alkali soil conditions (Rana et al. 1980). The ability to tolerate a wide pH range adds to the potential of S. aff. fimbriatus and S. pyramidalis for saline cultivation.

Transpiration

Salinity reduced transpiration per plant until after 4 weeks at 200mol m -3 NaC1 it was 25% of that for control (Fig. 8). During the final two-day interval of the 4 week trial, transpiration could be compared with leaf fresh weight and viable leaf area. Both of these were lowered by increas- ing salinity enough to account for differences in total tran- spiration per plant: transpiration rate per leaf fresh weight and per leaf area were similar for all three salt treatments (Table 3).

120

110

o 100 C o

90

8O

7o

~, 60

,~ 50 c3

40

20

30

20

10 �84 I0

1 0

140 -

130 -

120 -

110 -

o 100-

o

90- o

80-

.-~ 70- :>.,

60 - Ill

~- 50-

, ^

30

20-

561

130

140

130

120

110

: 100- o

g 90 -

80 -

-= 70- ._~

60 ._~ ~: 50

40 -

30-

' ' s ; ' ;o 2;0 ' 0 25 100 I 250

Salinity treatment (mo[ m - ] NaEl)

2 0

140 140

o

o

o

._~

._~ QJ

L

T I

I o

.~ 100 o =

90

80

70 "~,

60

. , 50 c3

4 0 -

30 -

20-

10-

0 I ; I I I L I

0 2 50 100 150 200 250

Salinity, treatment (mot m -3 NaC[)

130

140

130

120

II0

140

I ; I I I I I

0 2 50 100 150 200 250

Salinity treatment (mo[m -3 NaC[)

10-

0

130

120

110

100

9 0

80

70

6 0

50

4 0

30

20

10

0

/ 120

1

110

o 100

o = 90 'a

80

._~ 70

6O oJ 3 :.. 50

40

30

20

10

j , , 5 , , , , 6 0

0 2; 5; 1;0 150 2;0 250 0 2; 5; 100 1;0 200 250

Salinity treatment (molm -3 NaCU Salinffy treatment (molto -3 NaC[)

I I ; I I

0 25 5 100 150 200

Salinity treatment (molto -3 NaO)

Figs. 1-6. Effect of salinity on shoot dry weight production relative to dry weight production of control. Shoots were trimmed to 3 cm height initially, then harvested after 6 weeks treatment of soils with salinized Hoagland's solution (half strength). (Means __ standard errors). 'Between species', 'between salinities' and 'interaction' mean squares were significant (P=0.05). Fig. 1. Sporobolus festivus; Fig. 2. S. pyramidalis; Fig. 3. S. stapfi'anus; Fig. 4. S. aft. fimbriatus (Gaff 239); Fig. 5. S. pellucidus, Fig. 6. S. lampranthus

I

250

Salt content

The NaC1 content of leaves of S. aft. f imbriatus reached a maximum of 16.8% of the dry weight after 4 week with 200 mol m - 3 NaC1 treatment. Since leaf export fails to

remove much of the salt absorbed, continued accumulation of salt within the plant tissues was inevitable. In the first week, 60-80% of all salt absorbed remained the plant (Ta- bles 4 and 5). Over four weeks, salt retention was 90-94%. Long term removal in senesced leaves was not evaluated.

562

Table 1. Salinities giving yield reductions of 10%, 25% or 50% of control dry weight production

Species Mole NaC1 m-3 Salt tolerance e rating

10% 25% 50%

Sporobolus stapfianus 100 150 215 tolerant S. festivus 30 50 170 mod. tolerant S. pyramidalis 15 50 165 mod. tolerant S. aff. fimbriatus 20 30 150 mod. tolerant S. pellucidus 40 45 100 mod. sensitive S. lampranthus 5 15 35 sensitive Diplachne fusca" 60 120 220 tolerant Diplachne fuscab 70 110 200 tolerant S. virginicus c 100 150 200 tolerant Cyanodon dactylon d 130 160 180 tolerant Agropyron elongatum d 110 150 180 tolerant Hordeum vulgate d 80 110 140 mod. tolerant

" Sandhu et al. 1981 b Qureshi et al. 1982 ~ Breen et al. 1977 d Bernstein 1964 e on the system of Maas and Hoffmann 1977

Mos t of the salt was accumulated in the leaves. Lower NaC1 concentrat ions in roots p robab ly represent transient salt before its ascent in the t ranspira t ion stream. The content of both N a § and CI - rose linearly, as the applied salt con- centrat ion increased, but potass ium content was indepen- dent of external NaC1 concentrat ion and o f time.

Surface export

The contr ibut ion of leaf expor t to the overall salt resistance of S. aft. fimbriatus appeared to be small. Dur ing the first week of saline treatment, 20-40% of the NaC1 entering the p lant was exported onto the leaf surface, but over four weeks, leaf export accounted for only 6-10% of the salt absorbed (Table 5). Rates of foliar export of salt were low compared with other species: 0.1 to 0.3 gmol NaC1 cm -2 d a y - 1 at 200 mol m -3 NaC1 for S. aff. fimbriatus, com- pared with 1.5 ~tmol NaC1 cm -2 day -1 in 225 mol m -3 NaC1 for Avicennia marina, (Drennan and Pammenter 1982). No measurable traces of potass ium were found in any of the leaf washings. Salt glands and salt secretion under saline condit ions have been repor ted for S. arenarius, S. helvolus ; S. spicatus and S. virginicus (Liphschitz and Waisel 1974; Ramat i et al. 1976; Sen et al. 1982; Zahran 1982; Breen et al. 1977; King 1981; Zahran 1982). Under non-saline growth condit ions the salt glands could easily be mis taken for t r ichomes (Liphschitz and Waisel 1974).

n=

c

> o

.c 4--

~6

. o

no L

-m

aJ

Sporob. aff. fimbriafus

4

o

20

16

12

8

Sporobotus pyramidatis

pH

Fig. 7. The effect of soil pH on shoot regrowth ratios, i.e. final shoot harvest dry weight relative to initial shoot harvest dry weight. Means_+ standard errors for Sporobolus aff. fimbriatus (Gaff 239) and S. pyramidalis. ' Between treatments' means squares were not significant (P= 0.05) in either species

Salt exclusion

Of the theoretical potent ial uptake of NaC1, only 4.9 9.5% actually entered the plant, with 0.3-3.8% being exported by the leaves and 4.5 6.0% being retained within the plant tissue (Table5) . The 90.5-95.1% unaccounted for was taken as an est imate of root exclusion o f salt. The est imated percentage salt exclusion did not vary appreciably with con- centrat ion of saline treatment, nor greatly with the time of treatment. The most impor tan t salt resistance mechanism in S. aff. fimbriatus, then, appears to be exclusion of salt at the root. Significant exclusion of salt by roots is common in the Poaceae (Hannon and Barber 1972). While absolute quantit ies of salt entering the plant increased with salinity, the percentage salt exclusion was more or less constant for external concentrat ions from 100 to 200 mol m - 3 NaC1.

Table 2. Effect of salinity on shoot regrowth ratios, i.e. final shoot dry weight relative to dry weight of shoots removed from the same plants at the commencement of six weeks salt treatment. (Means • standard errors)

[NaC1] mol m-3 Sporobolus festivus S. aft. fimbriatus S. lampranthus S. pellucidus S. pyramidalis S. stapfianus

0 2.7• 4.1• 5.3• 2.8• 9.5• 1.0• 25 2.6• 2.5• 2.7• 3.4• 6.4• 1.2• 50 2.0• 3.0• 2.6• 1.8• 8.8• 0.8•

100 2.0• 2.4• 2.1• 1.4• 6.1• t .0• 150 1.5• 2.0• 2.4• 1.2• 5.1• 0.8• 200 1.2• 2.1• 1.9• l . l • 3.8• 0.6• 250 1.0• 1.7• 1.5• 1.1• 3.7• 0.4•

160

140

= 120-

100

~_ 80

g 6O %

�9 a_ 40 m

g t -

20

NaC[ mo[m -3

0

100

20O

563

Fig. 8. Effect of soil salinity on transpiration per plant of Sporobo- lus aft. fimbriatus (Gaff 239). (Means • standard errors)

Table 5. Pattern of salt distribution in Sporobolus aff. fimbriatus plants in saline soils. NaC1 is a percentage of potential uptake with the transpiration water (if NaC1 entered roots at the concen- tration present around roots). Means • standard errors

NaC1 NaC1 NaC1 ex- Total Excluded Conc. retained ported from NaC1 taken by roots

in plant leaf surface up by plant tool m -3 (=a) (=b) ( c=a+b) (100-c)

1 Week salinity treatment

100 5.96_+0.01 1.82_+0.05 7.78_+0.06 92.22• 200 5 .45_+0.20 3.28_+0.50 8.73• 91.27•

4 Weeks salinity treatment

100 5.02+0.51 0.52_+0.10 5.54+0.61 94.46_+0.61 200 5 .43_+0.34 0.36-+0.02 5.79_+0.36 94.21_+0.36

; 2'0 2', ' 4 8 12 1 26 100

Days saline 90

80

Table 3. Transpiration rate of S. aft. fimbriatus in soils of different 70 salinities, (a) transpiration per leaf fresh weight, and (b) transpira- tion per leaf area. Data are from a two-day extension of the experi- .~ 60 meat for Figure 8. 'Between salinities' mean squares were not sig- nificant (P=0.05) for transpiration on either a fresh weight or = 50 a leaf area basis. (Means • standard errors)

40

NaC1 in medium (a) (b) 30 (mol m- 3) g g- 1 leaf FW d 1 g cm- 2 leaf area

20 0 3.30 • 0.28 0.080_+ 0.006

100 2.91 _+0.16 0.063_+0.010 10 200 2.63 • 0.18 0.080 _+ 0.042

Table 4. Contents of chloride, sodium and potassium in leaves and roots of S. aft. fimbriatus plants after 1 week of irrigation with salinized Hoagland medium (half-strength). Means _+ standard er- rors

NaC1 concn. C1 Na K tool m-s % dwt. % dwt. % dwt.

Juvenile Leaves

0 0.16_+0.11 0 . 4 7 _ + 0 . 0 1 0.15_+0.01 100 2.06 _+ 0.10 1.09 _+ 0.06 0.14 • 0.01 200 3.14_+0.10 1 . 5 5 _ + 0 . 0 8 0.15_+0.01

Mature Leaves

0 0.58 + 0.01 0.46_+ 0.05 0.14_+ 0.01 100 1.98 _+ 0.05 0.98_+ 0.06 0.t4_+ 0.00 200 3.12_+0.08 1 . 4 4 _ + 0 . 0 0 0.14__.0.00

Roots

0 0.18 _+ 0.01 2.29 _+ 0.00 0.06 -t- 0.02 100 0.50 + 0.00 0.44 + 0.07 0.02 _+ 0.01 200 0.83 • 0.07 0.70 + 0.05 0.04 • 0.00

Cellular tolerance

The leaf tissue of S. aft. f imbriatus demonstrated reasonable cellular tolerance of NaC1 during an immersion period of 50 min. The percentage of cells surviving declined linearly

z I I l i

25 50 100 150 I

200 250

Salinify freafmenf {mo[m -3 NaG)

Fig. 9. Salt tolerance of leaf cells from Sporobolus aff. fimbriatus plants grown on Hoagland nutrient solution (half strength). Per- centages of cells surviving were counted after 50 minutes immersion in saline solutions. (Means_+ standard errors)

with increasing NaC1 concentrat ion (Fig. 9), reaching 50% survival at 200 to 250 mol m - 3 NaC1, which coincides with the concentrat ion around the roots for 50% reduction in dry matter increment compared to controls (Fig. 4). This concurrence would not be surprising if the root cells respon- sible for salt-exclusion had similar cell tolerance of salt to that of the leaf cells. This suggestion was not tested, as normal cell viability tests proved inappropriate for Sporobo- lus roots. Saline immersion times used for tolerance studies range from 30 minutes to 72 h (Taylor and West 1980), with the salt concentrat ion for 50% cell death decreasing with time. Species with high cell tolerance of salt generally have good overall salinity resistance as well (Monk and Wiebe 1961).

Salt effect on desiccation tolerance

Salt retained in plants (salinized for 3 weeks) did not com- promise the ability of desiccation tolerant Sporobolus plants to survive air-dryness after pre-treatments of up to 200 tool m -2 external NaC1. However, the proport ion of shoots

564

Table 6. Effect of pretreatment with soil salt on desiccation toler- ance. Plants were pretreated with salt for three weeks before they were allowed to dehydrate to air dryness. The salt was eluted from the soil before drying commenced. Values are mean numbers (___ standard errors) of live shoots as percentages of all shoots (includ- ing shoots which were senescent or dead before drying). Relative water contents (RWC) are given for leaves when air-dry

Saline soil pretreatment (mole NaC1 m-3)

0 25 50 100 150 200 250

Sporobolus lampranthus (8% RWC)

54_+8 50_+4 55+8 59_+3 50• 43+11 47+_5

Sporobolus aff. fimbriatus (6% RWC)

67+10 63___11 63_+8 44_+11 41+17 ~ 46___14 33+14 ~

Sporobolus pellucidus (11% RWC)

84___2 70+11 75_+8 48+14 62_+13 76+_7 24_+11 b

Sporobolus stapfianus (10% RWC)

70_+6 70_+7 57_+5 54_+18 20_+5 28_+11 a 6_+6 c

abe one, two, or three plants respectively, out of four, died

sprouting on rehydration usually decreased at salt concen- trations above this, except in S. lampranthus (Table 6).

Conclusion

The desiccation tolerant species S. aff. fimbriatus, S. pellucidus, and S. stapfianus, together with the drought resistant S. pyramidalis have sufficient salt resistance to warrant field investigation as pas- ture species in saline areas. In the species most fully studied, S. aff.fimbriatus, salt resistance stems mainly from 90-95% exclusion of salt by roots.

References

Bernstein L (1964) Salt tolerance in plants. U.S. Department of Agriculture Agricultural Information Bulletin 283

Boon PI, Allaway WG (1982) Assessment of leaf-washing tech- niques for measuring salt secretion in Avicennia marina (Forsk.) Vierh. Aust J Plant Physiol 9:725-734

Breen CM, Everson C, Rogers K (1977) Ecological studies on Sporobolus virginicus (L.) Kunth with particular reference to salinity and inundation. Hydrobiologia 54:135-140

Drennan P, Pammenter NW (1982) Physiology of salt excretion

in the mangrove Avieennia marina (Forsk.) Vierh. New Phytol 91 : 597-606

Gaff DF (1986) Desiccation-tolerant 'resurrection' grasses from Kenya and West Africa. Oecologia 70:118-120

Gaff DF, Ellis RP (1974) South African grasses with foliage that revives after dehydration. Bothalia 11 : 305-308

Greenway H, Munns R (1980) Mechanisms of salt tolerance in nonhalophytes. Ann Rev P1 Physiol 31:149-190

Hannon NJ, Barber HN (1972) The mechanism of salt tolerance in naturally selected population of grasses. Search 3 : 259-260

Hoagland DR, Snyder WC (1933) Nutrition of strawberry plant under controlled conditions: (a) effects of deficiencies of boron and certain other elements: (b) susceptibility to injury from sodium salts. Proc Am Soc Hort Sci 30:288-294

King RJ (1981) Mangroves and saltmarsh plants. In: Clayton MN, King RJ (eds) Marine botany: an Australian perspective. Long- man Cheshire, Melbourne, pp 308-328

Liphschitz N, Waisel Y (1974) Existence of salt glands in various genera of the gramineae. New Phytol 73:507-513

Maas EV, Hoffman M (1977) Crop salt tolerance current assess- ment. Am Soc Civil Eng Proc J Irrig Drain Div 103:115-134

Monk RW, Wiebe HH (1961) Salt tolerance and protoplasmic salt hardiness of various woody and herbaceous ornamental plants. Plant Physiol 36:478-482

Piper C (1944) Soil and plant analysis. Interscience Publishers, New York

Qureshi RH, Salim M, Abdullah M, Pitman MG (1982) Diplaehne fusca: an Australian salt-tolerant grass used in Pakistani agri- culture. J Aust Inst Agric Sci 48:195-199

Ramati A, Liphschitz N, Waisel Y (1976) Ion localization and salt secretion in Sporobolus arenarius (Gou.) Duv.-Jouv. New Phytol 76: 289-294

Rana RS, Singh KN, Parkash V, Ahuja PS (1980) Growing forage in barren alkali soils. Seeds and Farms VI; 37

Sandhu GR, Aslam Z, Salim M, Sattar A, Qureshi RH, Ahmad N, Wyn Jones RG (1981) The effect of salinity on the yield and composition of Diplachne fusca (Kallar grass). Plant Cell Environ 4:177-181

Sen DN, Rajpurohit KS, Wissing FW (1982) Survey and adaptive biology of halophytes in western Rajasthan, India. In: Sen DN, Rajpurohit KS (eds) Contributions to the ecology of halo- phytes. Dr. W. Jung Publishers, The Hague, pp 61-78

Taylor JA, West DW (1980) The use of Evan's blue stain to test the survival of plant cells after exposure to high salt and high osmotic pressure. J Exp Bot 31:571-576

Zahran MA (1982) Ecology of halophytic vegetation of Egypt. In: Sen DN, Rajpurohit KS (eds) Contributions to the ecology of halophytes. Dr W. Junk Publishers, The Hague, pp 3-20

Received May 18, 1988