II ()
s. Art. J. 1l01. 1999. (,5(1): Il ll- 112
Short Comm unication
Seed production of four Namaqualand
pioneer plant species grown on saline soil
A.J. de Villiers', M.W. van Rooyen and G.K. Theron
Department of Botany, University of Pretoria, Pretoria, 0002
Republic of South Africa
Recein.!d (j July 1998: revised 2n Octoher J998
The mining of heavy minerals along the west coast of South Africa
will destroy all the standing vegetation , and will also lead to the
salinization of the soil as sea-water will eventually be used in the
min ing process. Loca l, salt tole rant species should be selected for
the revegetati on of the area, and it is essential that the selected
species should be able to reproduce to ensure growth of the papula tion. Surviva l and seed production of fou r pioneer plant species
(Gazania leiapoda, Dfmorphoth eca pluvialis, Senecio arenarius
and Tetragonia microptera) we re determined along a salinity gradient (0-3% NaCI). None of the four species su rvived at the modera te and high salinities. Seed production of the ephemera l
species was red uced at the low salinity, while that of the perennial
species did not differ significantly.
Keywords : Mining; Namaqualan d; pioneer plant species; salinity;
seed produ ction
*To whom correspondence should be addressed .
The high acc umulation of salts in soils which could be caused by
any of several factors (eg. sal ine irrigati on water, inadequate
leaching. poor dra inage, naturally sal ine so il s) may hi nder germinati on, seed ling and vegetative growth as we ll as the yiel d and
qua lity of plan ts (Memo el 01. 1996). T wo maj or effects have
been ident ified as the probable causes of the detrimental effect of
sali nity all plant growth: the ionic effect and the osmotic effect
(Lewis el 01. 1989; Banuls "101. 1991; Leidi e l 01. 199 1).
Eve n though sal ine e nv ironments are unfavourable for most
plan t spec ies, so me pl ants, namely the halophytes , seem to fl ourish under these conditions. These pl ants have adapted to living
under these harsh conditions by eith er avoid ing salt uptake
through osmoregu lati on; excreting the sa lts by means of sa lt
glands and bladders; or tolerating the hi gh salt concentration as
euhalophytes or s uccul ents (Larcher 1995). Interspecific di ffe rences in response to sa linity and differential responses resul ting
from inlernction of sal inity with other environmental facto rs
occur. Variables such as irrad iance <;lnd calci um content (Hyder
& Greenway 1965; Boge mans et 01. 1989), ecotypi c variation
within spec ics (Tiku & Snaydon 1971 ), soils (Venables &
Wi lki ns 1978; Watt 1983), nitroge n levels and tem perature
Table 1
salinities
(Kemp & Cunningham 198 1), species (Kingsbury & Epstein
1986), CO 2 co ncen trations (M unn s & Termaat 1986) and humidity (Salim 1989), can a ll affect pla nt res ponses to sa lini ty. Several investigation s showed that salt tolera nce can vary with the
phenological stage and tha t the effects of sa line stress change
with its duration (Gutierrez Boem el al. 1997).
Along the western coast of South Africa, the sandy soi ls are
ri ch in heavy mineral s. Not only w ill the mining acti v ities in the
area destroy the topography, vegetation. soi l chemica l and phys ical characteristics and alter the animal life, but th e process
whereby the heavy minerals are extracted wi ll eventua ll y involve
the use of sea-water and, therefore, the sa linity of the mined soil
wili be inc reased to leve ls where plal1ls wi ll find it diffi cult to
grow (Environmen ta l Eva luation Uni t 1990). A lth ough severa l
local speci es are able to tolerate high sa lin ities (De Villiers
1993), it does 110t mean that they will produce seeds under these
conditions. The aim of thi s study was to determine if selected
plant species growing on saline soil a re ab le to surv ive and reproduce by means of seeds, and thus cont ribute towards the growth
of the popu lat ion and the success ful revegetat ion of th e area.
Seeds of natural popula tions of Ga:allia leiopoda (DC) Rc)ss l.
(perennial ). Tetragol1ia microptera Fell zl (ep hemeral). Dimorphotheca pillvialis (L.) Mot:m:h (ephemera l) and Senecio arenarillS
Th unb. (ephemaal). wcre collected at Bralld-se-Baai (31 ° 18'S.
17°54'E), South Africa. Alt hough members of the Asteraccac have
achenes and Telragollia microplera produces a samara, the term
seed will be used throughout this paper. These species were chosen
because they arc abundant and native to the area and/or seem to be
acting as pioneer speci es in surrounding areas (De Villic:rs 1993).
Seeds were sown in I dm 3 pots. contain ing fine sand (0 .5- 1. 1 111m
part icl e size). and irrigated daily wl lh tap walt!r. under free-draining
conditions. for a period of l\vo wet!ks. Thcrcafter. the plrll1ts were
th inned out to one plant pcr pot and irrigated daily under tl'ce drainin g co nditions. with 250 em] so lution having a sod ium chloride
(NaC l) concentration of dlhc r 1%. 2% or 3%. Distillt:d waler was
uscd as a control. The chemica ls of ha lf strength Arn Oll and Hoagland's nutrien t so lution (I kwi tt 1952) wcn~ added to all di lutions.
Salts. that might hav!.! acculllu lated in the soi l. were leached from the
soi l by giving cach pot 500 cm' distilled water t\vice a week. before
the sal ine solution was applied. A random izcd blockkss design was
used. Ont: plnn t was grown in each pOI and tcn repli cates of each
treatment (contro l: 1% NaC I, 2% NaCI and 3% Nael) were used for
each of the four species. Intlorescences/tlO\vers and matun:: seeds
\vere harvested an d counted before dispersal. Results were analysed
statistically as a blockless design using the one-way analysis ofvari'lIlce and LSD (Least Signilicant Diffe rence) mu ltiph! range test of
the Statgraphics 5.04 computer program. to test for signilic<1 nt di fferencl!s at a 95% co nfidence: h:vcl.
None of the four spec ies su rvived at sali nities higher than 1%
Nael (Table I J. A \though most of the plants of the four species
survived at the 1% NaCI treatment, th e e phemera l species
showed signs of chl oros is. T he mortality rate o f the four species
Survival percentages of four poineer species grown at different soil
' rrcatmen l
Control
l%NaC I
2% NaCI
3% NaG
Cn:Gllia leiopoda (pcrcnninl)
100
100
0
0
Senecio QI'enar/Us (ephemeral)
90
60
0
0
Te/r(lgonia microplera (ephemeral)
100
80
0
0
Dimorpholheca pJuviali~' (ephemeral)
90
70
0
0
Species
S. Atr. J. Bot. 1999, 65( I)
III
c 40
ro
a.
~
'"~
c
a
30
a
Q)
tl
'"o~
<;::
c
20
o
b
~
Q)
-E1O
a
a
:::J
c
c
ro
Q)
~
0
Control
G. leiopoda
S. arenarius
I_ Achenes absent 0
D. pluvialis
Achenes present
1
Figure I lh: mean number of inflorescences produced per plant, of Gazania feiopoda, Swecio arellarillS and Dimorp/lOilleca pll1vialis
grO\vn on saline so il. Bars with the same leiter are not signiJicantiy different at the P < 0.05 level.
increased as th e sa linity increased . The plants of the 3% NaCI
treatment died first (after three weeks), followed by the plants of
the 2% NaCI treatment (after nine weeks). De Villiers e( al.
(1997) found several perennial species of this area to be moderately salt tolerant. Although Gazania /eiopoda is a perennial species, it did not survi ve at the moderate and high salin ities as
ex pected.
In the case of Gazania /eiopoda (perennial), the mean number
of inflorescences produced per plant did not differ significantly
between the 1% NaCI and the control treatment (Figure I). The
mean number of seed bearing inflorescences were significantly
lower than those not beari ng seeds, for both the con trol and 1%
NaCI treatment. Al thou gh the mean number of seed bearing
inflorescences decreased when this species was grown on saline
soil, the total number of inflorescences produced did not differ.
The mean number of inflorescences produced per plant
decreased s ignifi cantly with increasing salinity, for both Senecio
arenarius and Dimorpholheca plaviaiis (Figure 1). In th e control
treatment, both these ephemeral species produced a significantly
greater numb er of seed bearing inflorescences than non-seed
bearing inflorescences. In the 1% NaCI treatm ent, the number of
seed bearing inflorescences were less than th e inflorescences not
bearing seeds, but thi s was onl y sign ificant in the case of Dimorpholheca plavialis. Therefore, the ephemeral species not only
produce less inflorescences when grown on saline soil, but the
inflorescences that are produced bear less or no seeds.
The mean number of seeds produced per plant are given in
Table 2. Alth ough not s ignificantl y, Gazania leiopoda produced
a greater number of seeds per plant in the 1% NaC I treatment
than in the control treatment, mainly because of the greater
number of seeds produced per inflorescence. A low salinity,
therefore, seems to enhance the number of seeds produced by
this species. Fra ncois and Kleiman (1990) reported that Crambe
abyssinica showed a 6.5% red uction of seed y ield for each unit
increase in soi l sa linity above 2.0 dS 111'1 , but no significant
reduction of seed yield below this concentration. The mean
number of seeds produced per plant decreased wi th increasing
salini ty for all three ephemeral species (Table 2). In the cases of
Dimorphotheca plovialis and Senecio arenarills, this decrease is
due to a red uction in both the number of inflorescences produced
per plant and the number of seeds produced per infl orescence,
with increasing salinity. A decrease in yield with increas ing
sa linity has bee n reported for many species (Abd ul-Halim el oJ.
1988 ; Francois e/ af. 1988; Francois el al. 1989; Jones e/ al.
1989; Francois & Kleiman 1990; Ashraf & Tufai l 1995 ; Ashraf
& O'Leary 1996; Mamo ef 01, 1996; Gutierrez Soem ef al.
1997). Abdul-Hal im el a/. ( 1988) found that at a low soil salinity
level « 8.0 dS n1" I) , and maintaining the available soi l water
above a specified percentage du rin g the growt h period, wou ld
effect a small reduction on wheat yield.
Although most ephemeral species survive when grown on soi l
with low sa linities, these spec ies yie ld almost no seeds, As seeds
are ephemeral species' on ly means ofreproduction, th ese species
will have to be revegetated from seed sources outside the mined
area, or from replaced topsoil. Fortunately, populations of repre sentative ephemeral species occur olltside the mined area, and
Table 2 Seed production (seeds/plant) of four pioneer
species grown at different soil salinities. For each species, values followed by the same letter do not differ significantly at P < 0.05
Treatment
Specit::s
Control
1% Nae!
GazQllia leiopoda
9.1a
t5.0'
Senecio arenarius
R07.8'
12.411
Fetragoflia lI1icroprcra
96.9'
2 1.9'
Dimorphotheca p{l/viali.f
77.2a
0.0'
S. Afr . .I. Bot. 1999. 65( I): 112-114
112
the seeds of Ill ost of these species are wind dispersed. If the
sa linity or the min ed soi l can be kept at a low conce ntrat ion, per·
ennial species will be able to survive and in some cases seed pro·
duct ion may even be enhanced. Stud ies compar ing the viabili ty,
longevity a nd gerl11 inabil ity of seeds, produced by pl ants grown
on so ils with diffe re nt sal ini ties, are now essential. Future studies
should also include emergence, seedling survival, plant growth ,
yield, etc. of plants derived from seeds produced at different soi l
salinities.
The authors would like to express their appreciati on to Miss Hester Steyn fo r her assistance during the experimen t, Anglo American Corporation and the Foundation for Research Development
for financial support , and the University of Pretoria fo r financial
support and fac ilities.
R.K..
salinity effects on growth. leaf anatomy and photosynthes is of Dis~
fichlis spicata (L) Greenc. American JOllmal of Botany 68: 507-6 16.
KINGS BURY. R.W . & EPST EIN. E. 1986. Salt sens iti vity in wheat.
Plant Physiology 80: 651-654.
LA RCHE R, W. 1995. Physiological plant ecology: ccophysiology and
stress physiology o ffunctional groups. Springer-Verlag, Berlin.
LEIDI, E.O .. NOGALES. R. & LIPS. S. H. 1991. Effect of sal inity on
cotton plants grown un der nit rate or [lmmonium nutrition at ditlerem
calcium levels. Field Crops Research 26: 35-44.
LEWIS, O.A.M .. LEIDL E.O. & LIPS, S. H. 1989. Eflect
nitrogcn
source on growth response to salinity stress in make and wheat. New
Phylologist I I I: 155- 160.
MAMO, T., RICHTER. C. & HEILlGTAG, B. 1996. Salinity efiects on
the growth and ion contents or some chickpea (Cieer arierinum L.)
and lentil (Lens clilinaris Medic.) varieties. JOllmal of Agronomy and
Crop Science 176: 235-247.
MUNNS, R. & TERMAAT. A. 1986. Whole-plant responses to salinity.
AuSlraJiall Journal of Plant Physiology 13: 143- 160.
SA LI M, M. 1989. Etleets of salin ity and rel at ive humidity all growth
and ionic relations of plants. New PhylO/ogist 113: 13- 20 .
TlKU . 8.L. & SNAYD ON , R.W. 197 1. Sa lini ty tolerance in the grass
species Agrostis stolonifera L.. Plnnt and Soil 35: 42 1-43 1.
VENABLES, A.V. & W ILKINS. D.A. 1978. Salt tolerance in pastu re
grasses. New Phylologist 80: 613-622.
WATT, T.A. 1983 . The effects or salt wa ter and soi l lype upon the germination, establishment and vege tative growth of HoiclIs lanatlls L.
and LoJiuflt perenne L. New Phylologisl 94: 275- 291.
or
Acknowledgements
References
ADDUL-HA LI M.
KEMP. P.R. & CUNN ING HAM. G.L. 198 1. Light. temperature mld
SA LIH.
H.M.,
AHMED.
A.A.
&
ABDU L-RAHEM . A.M. 1988. Growth and deve lopmen t of max ipak
whem as a nccted by soi l sal inity and moisture levels. Plallt and Soil
112: 255-259.
ASHRAI', M. & O ' LEARY , J.W. 1996. Responses of some newly
ucvclopl!d salt- to leran t genotypes of spring wheat to salt stress: 1.
Yie ld components and ion distribution. Journal of ,Agronomy and
Crop Science 176: 91- 101.
AS HRAF, M. & TUFAIL, M . 1995. Variation in salinity tolerance in
sunn ower (lfelinl1fhus onnllllS L. ). JOllmal of Agronomy and Crop
Sciellce 174: 36 1-362.
DANULS, J .. LEGAZ. F. & PRIMO-MILLO, E. 1991. Salinity-calcium
interactions on grO\\1h and ionic concen tration of Citrus plants. Plant
and Soil 133: 39-46.
BOGEMANS. J.. NE IRINCKX. L. & STASSART, J.M. 1989. [[feet of
deicing NnCI and CaCl 2 on spruce [Picea abies (L. ) sp. ). Plant and
Sail 120: 203- 2 11.
DE V ILLI ERS. AJ . 1993 . Ecophysiologica l studies on several
Namaqu aland pioneer species, with special rderence to the revegetati on of sa line mined soil. MSc. -disscrtation. University o f Pretoria,
Prelori".
DE VILLIERS, AJ., VAN ROOYEN , M.W., THERON, G.K. &
CLAASSENS. A.S. 1997. Tolerance of six Namaqualand pioneer
species to sJline soi l conditions. South African Joumal of Plant alld
Soil 14; 38-42.
ENV IR ONMENTAL EVALUAT ION UNIT 1990. Anglo American
Corpor~ ti on: West coast heavy mineral sands proj ect Unpub lished
rcport. University orCape Town, Cape Town.
FRANCOIS. L.E.. DONO VAN, TJ., LORENZ , K. & MAAS , E.V.
1989. Su iinilY effects on rye grain yield. quality, vegetat ive growth,
and emergence. Agronomy Joumal 81: 707- 712.
FRANCOIS.
L.E.,
DONOVAN. TJ.,
MAAS ,
E.V.
&
RUf3ENTHALER. G.L. 1988. Effect of salinity on grai n yield and
qual ity. vegetative gro\\1h. and germ ination of triti calc. Agronomy
JOllnwl 80: 642-647 .
FRANCO IS. L.E. & KLEIMAN, R. 1990. Salinity etTects on vegetati ve
growth. seed yield. and fatty acid composition o f cram be. Agronomy
JOlll1la/82: 1110- 111 4.
GUTIERREZ DOEM. F. H., LAVA DO, R.S. & PORCELLI, C.A. 1997.
Effects of waterloggin g followed by a sal inity peak on rilpeseed
(Brass/clf nupus L.). JOllmal of Agronomy and Crop Science 178:
135- 140.
HEWITr. E.J. 1952. Sand and wafer culture methods used in the study
of plant 1H1tritioJl. Farnham Royal. Bucks. Commonwealth Agricultural Bmeau.
HYD ER, S.l. & GREEN WA Y, H. 1965. Efte cls orCa:!" on plant sensitivity to high NaCI concentrations. Plant and Soil 23: 258-260.
JONES . R. W. Jr.. PIKE. L.M. & YOURMAN, L.F. 1989. Salinity intluences cucumber growth and yield. Journal of the American Society for
Horticultural Science 114: 547-55 1.
Technical communication
Progress with the trial phase for registration of new plant names
G.F. Smith' and G. Germishuizen*
' Research and Scientific Services Directorate, Nationa l Botanical
Institule, Private Bag XtOl , Pretoria, 0001 Republic of South
Africa
'Scientific Publications and Research Support Services, National
Botanical Institute, Private Bag X101 , Pretoria, 0001 Repub lic of
South Africa
Received I October 1998; revised II November 1998
In a spirit of co-operation and to publicise th is proposed innovation
in plant nomenclature widely in southern Africa , th is note has been
submitted simultaneously to the following botanical journals'. Bothalia, South African Journal of Botany, Forum Botanicum and SABONET News. A trial phase for the registration of new plant names
in South Africa , co-ordinated by the International As sociation of
Plant Taxonomy in Berlin, is introduced . Registration can be
effected by publishing a new name in an accredited journal or
series or by submitting it to the national Registration Office established for th is purpose.
Keywords : new plant names, reg istration , South Africa.
"To whom correspondence should be addressed.
Introduction
A number of far-reaching proposals aimed at the refinement and
simplification of the International Code of Botanical Nomencla-
ture were di scussed in some detail at the Nomenclature Section
of th e XVth International Botan ical Congress (!BC) held in
August 1993 in Yokohama, Japan. T hree of the main issues were