Identifying Germination Cues for Seven Basalt Plains Grassland Species Prior to Their Use in a Field Sowing

2010·2.6 MB·English

Research Reports
Identifying germination cues for seven Basalt Plains
grassland species prior to their use in a field sowing
Paul Gibson-Roy', John Delpratb and GregMoore^
'GrassyGroundcoverResearchProjectpartneredbyGreeningAustraliaVictoriaandIheUniversityofMelbourne,
500YarraBoulevard,Richmond,Victoria3121.Email:[email protected]
^SchoolofLandandEnvironment,TheUniversityolMelbourne.500YarraBoulevard,Richmond,Victoria3121.
Email:[email protected];[email protected]
Abstract
GerminationcharacteristicsotsevenindigenousgrasslandspeciesfromtheVictorian(Western) BasaltPlains
(Austrodanthonia racemosa, Bulbine bulbosa, Chrysocephalum apiculatum, Leptorhynchossquamatus, Leuco-
chrysumalbicansssp. albicansvar. tricolor, Linum marginalc, Wahlenbcrgiaslricta) wereinvestigatedpriorto
their use in a seeding program. Germination tests at20'710''C and I2hr/12 hr light/darkshowed a rangeof
maximum germination responsesfrom 21% (iV.stricla) to83% (A. racemosa). Two trendswereobserved in
termsofspeedofgermination.Austrodanthonia racemosa, Chrysocephalumapiculatumandl.inum mart>inale
germinateelrapidly(tH)<7and14days)andBulbinebulbosa. Leptorhynchossquamatus,Leucochrysumalhicans
ssp.albicansvar.tricolorand Wahlenbergiastrictaexhibitedaslowergerminationresponse(twbetween20and
30 days). When seeds ofeach species were exposed to smokeproduct, cool stratification and smoke cool +
stratification,Linum rnarginalewastheonlyspeciestorespondwith significantlyhighergermination (smoke
application).Furthertestingofsmokeproductatrecommendedandhigherratesproducedarangeofspecies-
specific dose responses, both positive and negative. These findings confirmed considerable species-specific
variationsinresponses,anddifferences/similaritiesofresponsesbetweenoursandotherstudies.Therefore,to
mostaccuratelygaugeseed-lotcharacteristics,itisrecommendedthatspeciesareroutinelytestedpriortotheir
useingrasslandrestorationprograms.(TheVictorianNaturalist127(5)2010, 184-191).
Keywords: grasslandrestoration, seedgermination,seedtesting,smoke, direct-seeding
Introduction
The Basalt Plains grasslands of south-western tion and stability, including mosses, lichens,
Victoria are a sub-set ofthe larger Australian liverworts and algae (that form cryptogamic
south-eastern lowland temperate grasslands. crusts on soil surfaces), soil-inhabiting arbus-
They currently exist as small and fragmented cular mycorrhizal fungi, invertebrate species
remnants distributed over an area ofapproxi- and a host of vertebrates, reptiles, birds and
mately23000 km^ offlatand undulatinglands mammals.
(approximately 1% of their original range). Initialattemptstorestoreorreconstructthese
These grassy communities are listed as threat- grasslands were primarilyundertaken through
ened under the Victorian Flora and Fauna the re-introduction of container grown plant
Guarantee Act (1988) and the Commonwealth material (Hitchmough 1994; Morgan 1999).
Environment Protection and Biodiversity Con- However, direct seeding has increasingly be-
servation Act (1999). They also have been rec- comethefocusofinvestigationandimplemen-
ognised by the Federal Government’s Threat- tationasa restoration technique (Morgan el al.
ened SpeciesScientific Committeeas oneof15 1993;HuxtableandWlialley 1999;Gibson-Roy
nationalbiodiversity‘hotspots’. 2005; Gibson-Royetal. 2007b). There arecon-
Basalt Plains grasslands are a diverse flora straints with both methods on the availability
characterised by tussock grasses, primarily and knowledge relating to the quality ofseed
Kangaroo grass Themeda triandra. Wallaby from abroad range ofgrassland species (Hux-
grassAustrodanthoniasp. and SpeargrassAus- table and Whalley 1999; Mortlock 2000; Gib-
trostipa sp., with a widevariety ofnative forbs son-RoyandDelpratt2006).
and both annual and perennial exotic species Whereavailable, seed resourcesmustbeused
(grassesandforbs) occupyingtheinter-tussock efficiently (whether for propagation or for di-
spaces. A variety ofother organisms from dif- rect seeding). To this end, restorationists re-
ferent trophic levels contribute to their func- quire information about seed-lot quality and
184 TheVictorian Naturalist
Research Reports
the germination characteristics of the species lar microscope (Olympus SZ x 20). Dissection
to be used (Gardiner and Midgley 1994; Del- confirmedthatvisualassessmentwasareliable
pratt 1996). Earlier formal studies examining predictoroffilledseed.
simulated environmental cues have revealed a Fortesting,sixreplicatesof25filledseeds (of
rangeofresponsesbyspeciesfromthisflorato each species) were sampled. Seeds wereplaced
diurnal light, stratification, smoke, fluctuating on white absorbent paper laid over towelling
temperatures, storage environments and stor- moistened with deionised water within lidded
mm mm
age periods (Willis and Groves 1991; Morgan rectangular plastictrays (210 x310 x
andhunt 1994;Dixonetal. 1995;Morgan 1998; 30 mm). One trayper species was placed into
Bell 1999; Clarkeetal. 2000; Gibson-Royetal. a germination cabinet set to alternating day/
2007a). In practice, grassland seed is seldom night temperatures of 20“C/10°C, with 12 hr
tested for qualitypriorto its use in restoration light (supplied byfourhighvoltagefluorescent
programs,potentiallylimitingthesuccessand/ tubes and four incandescent lights) and 12 hr
orinterpretationofoutcomes(Gibson-Royand dark during each 24 hr period. Each tray was
Delpratt2006). inspected at four-day intervals for 43 days. All
Theaimofthisstudywastotesttheresponse trays were rotated after each count to spread
ofseven grassland species to a range ofsimu- theeffectofanyvariationsinlightintensityand
lated germination cues for an indication of temperature within the cabinet. No fungicides
possible field responses. Seedtesting sought to were applied to the seeds during the germina-
establishthegerminationresponseofeachspe- tiontest.
cieswhenexposedto: Germination was recorded as the emergence
•projectedautumntemperatures; ofa radicle. Germinated seeds were removed
• cool-stratificationandautumn temperatures; aftereach inspection. Foreach species, the fol-
•plantderivedsmoke(atvariousrates). lowing germination characteristics were deter-
mined;
Methods • percentage germination after 20 days (G20)
Seven indigenous grassland species {Austro- and43days (G^
danthonia racemosa, Bulbine bulbosa, I.epto- • percentage incre3)a;se in germination from day
rhynchos squamatus, Chrysocephalum apicula- 20today43;
tum, Leucochrysum albicans ssp. albicans var. • timeelapsed(lag)betweenthestartofthetest
tricolor,Linummarginale, Wahlenbergiastricta) (imbibition) and the first germination. Spe-
representingarangeoffunctionalgroupsfrom cies were grouped into the following lag re-
theVictorian (Western) BasaltPlainsgrassland sponses: <7 days, 7-14 days, 15-28 days, >28
community(C3Grass,Geophyte,Hemicrypto-
days;
phyte, Chamaephyte) were selected fora seed- • time elapsed between imbibition and 50% of
ing project. Seed was sourced from roadside final germination (tso). Species were grouped
populations occurring on basaltic soils near intothefollowingtsoresponses: <7days, 7-14
Cressy in Victoria’s South West in spring and days, 15-28days,>28days.
summer. Seed from two species was sourced
from production crops grown at Burnley Col- GlasshouseExperiment1. Effectsofcoolstrati-
lege. After harvest, seed-lots were dried and ficationandsmokeonseedlingemergence
stored inpaperbagsatroomtemperature until A glasshouse experiment investigated the ef-
testing (and subsequent sowing in the follow- fectofcoolstratification and theapplication of
ingautumn). commercial smoke vermiculite (Grayson Re-
gen 2000*Seed Germinator)ontheemergence
Germination test of seedlings of each species. The experimen-
All seed lots were cleaned by removing unat- tal units were 340 mm x 320 mm black plas-
tached inert matter. Based on the appearance tic seedling trays. In each tray, the seeds ofall
of individual propagules, seed-lots were then species were sown in rows at 40 mm intervals
sampled forfilled and unfilled seeds. To deter- onto a pine bark propagation medium. Sown
mine if plumpness was a reliable indicator of seeds were covered with either medium grade
thepresenceofan embryo, sub-samples of100 vermiculite or a blend ofmedium grade ver-
seedsfromeach specieswererandomlychosen miculite and Grayson Regen 2000® Seed Ger-
for inspection and dissection under a binocu- minator smoke vermiculite (ofsimilar particle
Vol 127 (5) 2010 185
Research Reports
size). The position ofspecies within each tray ofseedlings was recorded weekly for 89 days.
wasrandomlyallocated.Thesowingdensityfor Seedlingswerenotremovedafteremergence.
each species was dictated hy propagule mor- The following e.xperimental treatments were
phology and size. If seeds were easily cleaned imposed.
andcountedtoindividuals,25seedsweresown 1. Control:- nosmokeproduct.
ineach row. Ifprotectiveordispersalcoverings 2. Smoke concentration 1:- Grayson Regen
made it difficult to isolate individual seeds, a 2000® Germinator @ 600 ml, m- (manufac-
known masswassown ineachrowtoachievea turersrecommendedapplication rate).
target sowing ofapproximately 25 propagules. 3. Smoke concentration 2:- Grayson Regen
Treatmentswereappliedtotraysrandomlyand 2000* Seedstarter@ 18 ml.m- (equivalentto
each treatmentwasreplicatedfourtimes.Trays application ratein Treatment 2).
wereplaced onaglasshousebenchin fourran- 4. Smoke concentration 3:- Grayson Regen
domised blocks. All trays were watered twice 2000* Seedstarter at 180 mL m’ (ten times
daily during the study period. The number the smoke product concentration of Treat-
ofseedlings was recorded weekly for 89 days. ments 1 and 2).
Seedlingswerenotremovedafteremergence. The data for each study were tested for nor-
The following experimental treatments were mality using Ryan-Joiner and, where required,
imposed. logtransformedtosatisfyheterogeneityofvari-
1. Control:- sowntraylightlycoveredwith200 ance. Differences were compared using ANO-
mLofvermiculite. VAswith thestatistical softwareMinitab 15.1.
2. Cool stratification:- sown tray lightly cov-
ered with 200 mL of vermiculite, watered Results
andplacedinto acool room atapproximately Germination test
4°C for 14 days prior to transferto theglass- Germination occurred for all seven species.
house. However, there were differences between spe-
3. Smoke:- sown tray covered with a blend of cies in the speed ofgermination and in the fi-
140 mLofvermiculiteand60 mLofGrayson nal germination percentage (Fig. 1). At day 43
Regen 2000"’ Seed Germinator smoke ver- Austrodanlhonia racemosa and Chrysocepha-
lum apiculatum e.xhibitedthehighestgermina-
miculite.
4. Cool stratification + smoke:- sownseedpre- tion figures (>80%), while Wahlenbergiastricta
pared as per the smoke treatment; trays were recorded the lowe.st germination (21%). A.
placed into a cool room at approximately racemosa, C. apiculatum and Linum marginale
4°C for 14 days priorto transfer to theglass- germinatedquickly,reachingbetween40%and
house. 60% germination within 5 to 10 days ofimbi-
bition. Conversely, although liulbine bulbosa,
GlasshouseExperiment2. Effects ofdiffering Leptorhynchos squamatus and Leucochrysum
formulationsandratesofapplicationofsmoke albicans began to germinate within 10 days of
vermiculite imbibition, each reached less than 10% by day
This experiment investigated the effect ofdif- 15. Wahlenbergia stricta germinated from day
fering application rates of the commercial 16 but total germination reached only 21% by
smoke products Grayson Regen 2000® Seed day 43. Four species, B. bulbosa, Leptorhyn-
Germinator smoke vermiculite and Grayson chossquamatus, Leucochrysum albicansand W.
Regen 2000®Seedstartersmokevermiculiteon stricta showedsignificant (>100%) increases in
theemergenceofseedlingsofeachspecies. germinationbetweendays20and43. However,
The seed forthisexperimentwasprepared in of these species only Leucochrysum albicans
the manner described for the Glasshouse Ex- achieved final germination greater than 50%
periment 1. Each experimental unit was a 100 (Table 1).
mm
X 100 blackplasticpropagation tray. Seeds
weresown ontoapinebarkpropagation medi- Glasshouse experiment 1. Effects ofstratifica-
umattheratesdescribedinGlasshouseExperi- tionandsmoke
ment 1. Experimental units were randomly al- Atlrleastpmeecnitess.geOrnmliynaLtienduumndmearrgthienaelxepeerxihmiebnittaeld
locatedwithinthreereplicateblocksonabench
significantly increased emergence in response
in an unheatedglasshouse. Allcontainers were
watered automaticallytwice daily. The number toanytreatment. Forthatspecies,thestratifica-
186 TheVictorianNaturalist
Research Reports
nFiagt.in1g.tMeemapenrgaeturrmein(a2t0i"o/n10(“C+)/-anSEd)liogfhtse(v1e2nhrg/rlaisgshlta1n2dhsrp/edcaireks)o.vAerr=43Audsatyrsoudnadntehrocnaibainreatcecmoonsdai;tiBobns=oBfulalbtienre-
bulbosa; Ca = Chrysocephatum apkulalunv, l.s = Leptorhyncossquamatus-. La = Leucochrysum albicans spp.
albicansvar. tricolor;Lm=Linummarginale;Ws= Wahlenbergiastricta.
tion (11*’), smoke -i- stratification (15‘’) andthe cochrysum albicans and Linum marginale (p <
smoke treatment (23‘) gave enhanced emer- 0.05). There was no significant effect on seed-
gence(p<0.05)overthecontroltreatment(5“). lingnumbersofLeptorhynchossquamatus. The
However, the smoke and the stratification -f number of seedlings of Bulbine bulbosa in-
smoke treatments resulted in the highest ger- creased significantly in trays treated with this
mination. higherrateofGraysonRegen2000®Seedstarter
(p <0.05).
Glasshouse Experiment 2. Effects ofdiffering
formulationsandratesofapplicationofsmoke Discussion
vermiculite The restoration of threatened grassland com-
Exceptfor Wahlenbergiastricta,seedlingsofall munitieswill require access to, andknowledge
speciesemergedduringthis experiment (Table of,ascarceseedresource.Thesevenspeciesex-
2). For emerging species, results were similar amined in this study are representatives from
in treatments common to this experiment and thisflorallydiversecommunityandeachislike-
GlasshouseExperiment 1.Therewasalsoclose ly to be included in restoration programs. The
agreement between the results for treatments testsconductedinthisstudyrevealedarangeof
that compared the two formulations ofsmoke species-specific responses to temperature and
vermiculite when theywere appliedat the rate smoke cues that may guide plant propagators
recommendedbythemanufacturer.Aswasthe and restorationisls undertaking propagation
case in Glasshouse Experiment 1, only Linum andseedingprograms.
marginale responded positively to the smoke
products at recommended rate (Regen 2000® Germinationcabinettesting
Germinator - 600 mL m^ and Regen 2000® All seven species were germinable under a
mL simulated autumn/spring 20'’/10‘’C tempera-
Seedstarter- 18 m‘^).
ture regime. Species-specific responses were
Theapplicationofsmokeproductat 10times
the recommended rate (Grayson Regen 2000® highlighted through differences in speed of
Seedstarter- 180 mLm significantlyreduced germinationandthefinalgerminationpercent-
the number of seedlings of Austrodanthonia age. Theseobservations areconsistentwith the
findings ofMcIntyre (1990), Morgan and Lunt
racemosa, Chrysocephalum apiculatum, Leu-
(1994), Morgan (1998), and Gibson-Roy et
Vol 127 (5) 2010 187
Research Reports
daTaanybdsl;leiGg12hn.t-G4(e31r=2mih%rnailtnicigrhoetna/1sr2eeshipnrogdneasrrekms)i.onfaGs2t0eivo=ennmfgerraoamnssd%laaygnde2r0smpiteoncaidetasiyoan4t3da;aftLyeAr43G20u(nddadayyessr;)aG-l4t3dear=nyasmteeilnaganpts%eemdpgbeereratmtiwuneraeetni(io2mn0b°ia/fbt1ie0tr°iC4o)3n
andfirstgermination;tso(days) =dayselapsedbetweenimbibitionand50%offinalgermination.
Genus/Spedes Gao G43 G20-43 LAG tso
(%) (%) (%) (days) (days)
Austrodanthoniaracemosa 69 83 20 <7 <7
Bulbinebulbosa 23 49 113 7-14 15-28
Chrysocephalumapkulatum 64 82 28 <7 7-14
Leptorhynchossquamatus 12 40 233 7-14 15-28
Leucochrysumalbicans 16 75 369 <7 15-28
Linummarginale 51 53 4 <7 <7
Wahlenbergiastricta 3 21 600 7-14 15-28
Table2,Meanseedlingnumbers(Standard Deviation)atthecompletionoftheGlasshouseStudy2imposing
2di0f0f0e®[email protected]=lG=rnaoysaopnplRiceagteinon2o0f00s®moSkeeedvsetramritceurl(i®te1;8smmLokmehI =smGorkaeys2o(nhiRgehg)e=n
GraysonRegen 2000®Seedstrater@ 180mLm Differentlettersindicatesignificantdifferenceswithin rows
followingOne-WayANOVA(p<0.05).ns=notsignificant.
Genus/Species Control Smoke 1 Smoke2 Smoke2(high)
Austrodanthoniaracemosa 37'(1.5) 38 (4.6) 36'’(1.8) 10“(3.0)
Bulbinebulbosa 5“(1.5) 10'’(0.3) 7»(2.5) 15'’(1.5)
Chrysocephalumapkulatum 40I"(13.5) 62'’(14.6) 54'’(7.1) 21“(7.5)
Leptorhynchossquamatus 20“(9.0) 18“(3.5) 14-“(1.0) 11 “(2.5)
Leucochrysumalbicans 23'(0.8) 18'’’(0.5) 16”(2.5) 11“(2.5)
Linummarginale 8'>(0.2) 18’(0.7) 16’(1.1) 1 “(0.5)
Wahlenbergiastricta 0 0 0 0
al. (2007a). It is unlikely that any single set of rapidlyuntildayseven (40%),afterwhichlittle
temperature and/or light regimes will provide furthergermination occurred (53%at day 43).
optimalgermination conditionsforabroadse- Thisisacommonlyobservedpatterninrecent-
lection ofgrassland species. This is an impor- ly-harvestedseedofthisspecies (JohnDelpratt
tant issue for field sowings ofcomplex species unpub. data). Conversely, there were few ger-
mixes. Itis unrealistic toexpectrapid and syn- minants of Leucochrysum albicans up to day
chronous emergence of all species under any 15 (10%), after which germination increased
combinationoffieldconditions. rapidly, reaching 75% by day 43. However, we
In general, the species exhibited two patterns areawarethatthelag(andtso)periodforLeuco-
intermsofthespeed atwhich germinationoc- chrysum albicans reduces to a few days follow-
curred.Onegroup {Austrodanthoniaracemosa, inglongerperiods ofdrystorage (> 3 months)
Chrysocephalum apkulatum, Leucochrysum (Gihson-Royand Delpratt,unpub.data).
albicans, Linum marginale) began to germi- Comparisonofourresultswith thoseofsimi-
nate rapidly (lag < 7 days). The second group lar studies indicates that testing of the same
{Bulbinebulbosa,Leptorhynchossquamatusand species can result in both similarities and dif-
Wahlenbergiastricta) wereslowertogerminate ferences in germination responses. For exam-
(lag 7-14 days). These responses are consistent ple, final percentage germination for Austro-
with results reported by Morgan (1998), who danthonia racemosa was (G43) 83%. This is
foundthatC.apkulatumandLeucochrysumal- similartoGibson-Royetal. (2007a) (Gas95%).
bicanshadlagtimes of< 7 days, Leptorhynchos C. apkulatum (G4382%)wassimilartoMorgan
squamatusalagof7-14daysandthatB. bulbosa (1998) (Gsfi87%),andWillis<indGroves(1991)
exhibitedalagof14-28days. (G 94%). Conversely, Leptorhynchos squama-
6o
Interestingly, a short lag period did not al- tus (G43 40%) exhibited a higher germination
waysresultinahighfinalgerminationpercent- percentage than reported by Morgan (1998)
age. Forexample,Linum marginalegerminated (G56 20%) and Gibson-Roy et al. (2007a) (Gas
188 TheVictorianNaturalist
Research Reports
16%), as did W. stricta (G4321%)compared to had been exposed to cool stratification. In the
WillisandGroves(1991)reportof0%germina- case of L. albicans, Willis and Groves (1991)
tionafter60days.Ourfindingof49% (G43)ger- found it had the effect ofincreasing germina-
minationforB. bulbosawaslowerthanMorgan tion. Our findings suggest that cool stratifica-
(1998) (G5674%),buthigherthanthatreported tion priortopropagation orseedingwouldnot
byGibson-Roy et al. (2007a) (Gi# 14%). These enhancegerminationoremergenceofthesesix
differences in germination responses between grassland species.
tests and studies can result from differences InGlasshouseExperiment2,wetestedtheef-
in maternal conditions, seed collection tech- fects ofsmoke products at recommended and
niques, cleaning and storage techniques, cabi- higher rates. As was expected, we observed a
net environments and observation periods. significant enhancement of germination over
Thisconfirmsthatthetestingofseed-lotsprior the control treatment for L. marginale using
to their use in restorationprogramswill give a recommended rates of Grayson Regen 2000®
moreaccurateindication ofgerminabilitythan Germinator (600 mL m^) and Grayson Regen
willhistoricalinformation forthatspecies. 2000® Seedstarter (18 mL m^) treatments.
This confirmed the finding ofGlasshouse Ex-
Glasshouseexperiments
Coolstratificationandsmoke pmeirniamteinotn o1fatnhdisfsupretchieersicndaincabteessttihamtultahteedgebry-
Dixon etal. (1995) reported that the germina- the application of either of these commercial
tion ofmanyWestern Australian speciescould formulations (at recommended rates). Inter-
bepromotedbytheapplicationofplant-derived estingly, Wahlenbergia stricta failed to emerge
smoke. Since then, a number ofother studies under any treatment. The reason is not clear
havereportedvaryingresponsestosmokecues as seeds from the same seed-lot germinated/
across a broad range ofAustralian forest and emerged (albeit at low rates) in the other two
understoreyspecies (Roche etal. 1997; Tieu et experiments and in subsequent field experi-
al. 1999; Clarke et al. 2000; Lloyd et al. 2000; ments (Gibson-Roy 2000). It is possible that
Merritt et al. 2006; Thomas et al. 2007). Such the dormancy status ofseed from this species
studies indicate that while a number of spe- had increased by the time ofthis experiment,
cies showapositive responseto smoke deriva- suggesting that this species may experience
tives, many others exhibit no, or only a small, dormancycycling(BaskinandBaskin 1998).
response to smoke or smoke derivatives under Consistent with Glasshouse Experiment 1,
laboratory or glasshouse conditions (Clarke et other than Linum marginale, our species did
al. 2000; Merrittetal.2007). not respond significantly to smoke at the rec-
In Glasshouse Experiment 1, the emergence ommended application rates (both Grayson
ofLinum marginalewassignificantlyenhanced Regen 2000® Germinator and Grayson Regen
above that ofthe control treatment (20%), us- 2000® Seedstarter). However, when compared
ing smoke vermiculite, cool stratification and to the control treatment, emergence ofLeuco-
a combination ofsmoke vermiculite and cool chrysumalbicanstendedtoreducewithincreas-
stratification. However, the smoke treatment ingconcentrationsofsmokeproduct,becoming
on its own resulted in significantly higher increasingly significant with increasing rates
emergence (92%) than smoke + stratification of Grayson Regen 2000® Seedstarter. Drewes
(60%) and the stratification (44%). This infor- et al. (1995) reported that exposure to smoke
mation, coupled with the lack ofevidence for product (smoke water) at high concentrations
anyseriousinhibitionoftheotherspecies,sug- was inhibitory to lettuce germination. Obser-
gests that the application of smoke might be vations from our study also suggest that there
consideredwhenpropagatingthisspecies. is a potential to both inhibit and promote the
Forthe other species, neithersmoke applica- emergence ofplant species using higher rates
tion, cool stratification, nor a combination of ofsmokeproducts. Forexample,thereduction
both, resultedinenhanced seedlingemergence in emergence of Austrodanthonia racemosa,
above that ofa control treatment. Again, these Chrysocephalum apiculatum, Leucochrysum
responses are not always consistent with find- albicansandLinum marginale,andthepromo-
ingsfromearliertesting. Forexample,Clarkeet tionofBulbinebulbosaatthe 180mLm*^appli-
al. (2000) reportedloweremergenceofBulbine cation rate (Grayson Regen 2000® Seedstarter)
bulbosa and Leucochrysum albicans after seed
Vol 127 (5) 2010 189
Research Reports
clearly demonstrate a concentration response ingredient will continue to limit the interpre-
to plant-derived smoke. This observation is of tation of results of experiments using generic
relevance to propagators and restorationists, plant-derivedsmoke.
and suggests when using commercial smoke
products that care should betaken to establish Implicationsforgrasslandrestoration
themostefficaciousrates. The three experiments reported in this study
The t)'pe ofsmoke formulation used in this investigatedthegerminationandemergencere-
study (smoke vermiculite) will be of interest sponsesofsevengrasslandspeciesexposedtoa
to nurserypropagators (Grayson Regen 2000® selectionoftemperatureandsmokecues.These
Germinator) and restorationists (Grayson Re- species were then to be included in a seed mix
gen 2000® Seedstarter) where it can be dem- for a subsequent seeding program. It remains
onstrated that particular species respond to unclear whether investigations ofthis type al-
smoke. Bothcommercialformulationsarerela- low for accurate predictions ofseed behaviour
tivelysimpleto handleand applyand their use under field conditions. However, the range of
in both the nurseryand thefield mayenhance responsestogerminationcues,bothwithinand
seedlingemergence.Aminorreservationabout betweenspecies,meanthatsitepreparationand
theuseofRegen2000 Germinatorfornursery post-sowing planning for the field sowing of
seedling propagation is that its recommended complexseed mixesmust anticipateprotracted
rate ofapplication does not provide sufficient and asynchronous emergence. Therefore, the
cover on a seedling tray to produce the other resultsprovidedabasisfordecisionsaboutseed
benefits ofvermiculite sought by the propaga- mixcomposition, species-specific sowing rates
tor. For this reason, the volume ofvermiculite and sowing treatments (e.g. sowing season,
applied in these experiments was increased whethertoapplyasmoketreatment).
with untreatedvermiculite ofa similarparticle Ourfindings add to a growingbodyofinfor-
size. mation that is improving the efficiency with
Also, under field conditions the potential for which limited seed resources are used. They
plant-derived smoketo stimulate thegermina- confirmconsiderablespecies-specificvariations
tion ofweed species must be considered. In a in responses, and differences/similarities ofre-
study of smoke effects on soil seed bank ger- sponsesbetween our results and other studies.
mination from eucalypt forest in the Hunter To better guide nursery and field seeding de-
Valley ofNew South Wales, Read et al. (2000) cisions, we strongly recommend that nursery
found that germination enhancement was not propagators and field practitioners should test
limited to native species. They reported that seed-lotcharacteristicspriortotheinitiationof
while a number of native species responded agrasslandrestorationprogram.
positively to plant derived smoke, four weed Acknowledgements
species (oneannualandthreeperennials) were ThankstoPeterMay,JohnMorganandtotheanony-
alsostimulated. mous reviewer who each made helpful suggestions
Karrikinolide (the butenolide 3-methyl- on versions ofthe manuscript. Paul Gibson-Roy is
2Hfuro|2,3-clpyran-2-one, KARi) has been project head of the Grassy Groundcover Research
Project partnered by Greening Australia Victoria
identified as a germination-active chemical andTheUniversityofMelbourne. John Delprattand
present in smoke (Flematti et al. 2004; Chiwo- Greg MoorearemembersoftheSchool ofLandand
cha etal. 2009). Identification ofthis molecule Environment at the University of Melbourne, 'fhis
hasallowedvariousresearchgroupstoconduct research arosefrom the need to progress the use of
more precise germination experiments using directseedingintherestorationofthreatenedherba-
knownconcentrationsofthischemical(Merritt ceousplantcommunities.
et al. 2006). However, the commercialisation Reference.s
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Onehundredyearsago
—
THEUTRICULARIAS. RvonHuetzelburg,inFlora,c.(1909)p. 145,givestheresultsofastudyofvari-
ousspeciesofVtriculariaandcomestotheconclusionthattheyaretrulyinsectivorous,beingabletodigest
theinsectswhichtheycatchowingtothesecretionofanenzymeandanacid.Thehairswhichentrapthe
insectssecretesugarandmucus,buthavenodigestiveaction.Thebladdersareallofsimilarstructure,and
theflapclosessotightly,owingtothemucuspresent,thatnoinsectscanpossiblygetout.
From Tlte VictorianNaturalistXXVU,p.30,June, 1910
Vol 127 (5) 2010 191