A. K. Mitchell,Canad an ForestService, Pac f c ForestryCentre 506 West Burns de Road VictoriaBritish Co umba V8Z1M5

Propagationand Growthof Pacific Yew(Taxus brevifolia Nutt.) Cuttings

Abstract

Vegetativepropagation techniques for Pacillc ye$ (Id.r!J b/ew&/id Nurt.) are little lnown and could bc useful for the anage- nert of thii tong livea undersloryspecies whether for conscrvation,habilat restoration or ior theproduclion of Taxol@lpaclilaxel), a promising anti cancer agent. In this study. cutringslrom natural stendsof Pacific yew on Vlncouvcr ldand \lere uscd to te\t threecomp;nents ofa suciessful vegetativepropagation program; nurseryculture, rooling success,and shoot growlh and orien- tation oir;oted cultings. Cultural studiesshowed that Pacific ye\l cuttingscould be eftectivelypropagated but successratcs ma,v not ncet expectarionJderiled fiom studiesof other lar(r species.Rooting studjesshowed lhat cuttings iiom male an{l lemale pacific yew could be rooted equalllr successfully.No significant differencesucre found in rooting percenlagcsoi parent trecs froln 6 VancouverIsland populations. Clonal variatjon in rooting was signil-rcantwithin lhosc populations (87 5% maimum. 6.4q. minimum). Shoor g;owih of roored curtings increasedliom 3.4 cm in the first year after transplanling!o 15.7 cm in the secondyear. All fie cuttingshadbranchlike orienration-Resuhs showed that a Pacificyew consen'ationprogram for theVancouvcr lsland Region basedon vegetativepropagation of repfesenlativegenollpes is feasible lntroduction tratedon ornamentalvarieties (Eccher 1988).As a result,rooting successof cuttingsfrom natural (?a'I'rs having little Pacific yew br€viloli.r Nutt.), sland\ol Pacificye$ ma) not meele\pectations. past, is one speciesof commercial value in the Cultural studiesthat test rooting methodsestab- nursery which little is known about successful lished for other woody specieswould be an im- would propagationtechniques. Such information portant first step in the developmentof a man- of this longJived be uselul in the management agementprcgram based on vegetativepropagatton grows slowly and is scattercdin specieswhich (oni 1993). the understoryof Northwest forests (Busing et yew species(Bolsinger al. 1995). tn addition, recently Pacific yew has Pacific is a dioecious differencesin rooting receivedgreater attention due to the clinical suc- and Jaramillo 1990) and treesmay re- ce.. ofTaxolO{paclit:r-rel r.a promi.inganti-cucer capacitybetween male and female succes.in a regetrtire drug extractedfrom the bark.This hasraised con- ducethe probubilitSof (Japa- cern about the exploitation of natural standsby propagationprogram. In Taxusctrspidata from haryestingand the consequentloss of genetlcre- neseyew), a greaterpercentage of cuttings (Davidson sources(Scher and Schwarzschild 1989). Due to female tlees rooted than fiom male trees problems with the acquisition and germination and Olney 196,1).In somedioecious species, dif- of Pacific yew seed (Rudolf 1974), vegetative ferencesin physiologicaland morphdogical traits propagationcould be a feasible way to achieve have been found between males and females conservationand restorationgoals as well as to lDawsonand Ehlerrnger lgtr.lr lirootinp caprc- meet the demand fbr paclitaxel (Heinstein and ity i: oneof lho:'e1'xi1s. regetatire pr,'pngrtion Chang 199,1).Vegetative propagaiion has been of one sex or the other may be problematlc. successfullyused in a program of consewation Increasingparent tree age and low growthvigor of genetjc resourcesof some medicinal woody are olher factor\ known to reducerooling \uc- plantsin Nigeria(Oni 1993). cess(Meier-Dinkel andKleinschmidt 1990,Rob 1966) thg 5ucqq..,rf u Pacilicl ew r egetutire propa- eftsand Moeller 1978,Libby andConkle gation program dependson whether male and and cuttingsfrom someindividuals may not root female trees from a variety of geographicloca- at all, particularly if they are over 100 yearsold tions can be effectively propagated,grown and (Brix 1974). Pacific yew cuttings tiom natural outplanted.But little is known aboutrooting cut- standsmay be dillicult to root becauseparenttrees tings of Pacific yew (Mitchell 1992) and studies can often be over 195 years-old and tend to be of rooting in other lclis specieshave concen- slow-growing(Busing et 41.1995). Therefore. old

56 NorthwestScience, Vol. 71, No. l, 1997 O 1997 b) rlc Nonhse\t SotntiUc Asrociaton All nghls F\erv€d age and low vigor may combine to reduceroot- tions or latitudeswould be dill'icult to propagate ing successin cuttiogsofPacific yew from natu- and grow successfully. ral stands.This would tend to compromisethe feasibility of a conservationprogram. Materialsand Methods Thereare also indications that rootjng may vary The following methodswere used for both cul- amongparent fees from different geographiclo- tural androoting studies.Branches were collected cations (Ticknor 1969). However, the extent to ftom the mid to lower crown of mature(bearing which environmentalfactors affect tree vigor and pollenor seed)Pacific yew (.TaxusbrevifoliaNutt.) thus rooting is not well understood(Abedini and found in natumlstands on VancouverIsland. They Marlats 1988,Libby and Conkle 1966).Pacific were baggedin plastic and returnedto the labo- vew is \i'idely scatteredin its distribution (Bolsinger mtory where they were stored at 2'C. All cut andJaramillo 1990, Taylor and Taylor 1981).It tings were made within l0 days of collection. is fbund at elevationsup to 800 m and over the Cuttings were set in a mixture of equal parts of entire length and breadth of Vancouver Island sand,peatandperlite and placed in outdoorpropa (Krajina et al. 1982), an area of great climatic gationboxes (Brix 1974)withbottom heat(20"C) andecological diversity (Green and Klinka 1994). to roor.During rooring. hiph humid iry was main- Therefore,propagation ofPacific yew from stress- tained and the medium was wateredregularly. ful (e.g.dry or cold) sitesmay be problematicas a result of poor shootgrowth vigor of the parent CulturalStudies trees. Four basiccultural experimentswere conducted. Good shootgrowth and updght shootgrowth Becauseofa scarcityof suitablematerial tbr cut- orientation of outplantedrooted cuttings will be tings, eachused dillerent parenttrees (=ortet). In important ifthey areto suryive in naturalstands, any given experiment,parent trees were from the parlicularly en siteswherc competingvegetation samegeographic location. Equal numbersofcut- is a problerntbr seedlingestablishment. Such sites tings ({amet) were setin eachtreatment are common in the Pacific Northwest (Helring in each experiment.Rooting was assessed after 5 months and Etheridge 1976) and on Vancouver Island by counting the number of with (Koppcnaaland Mitchell 1992).Poor shoot growth cuttings at least percant is charactedsticof Pacific yew in natural stands one root and expressingrooting as a of the total number (Busing et al. 1995) and outplantingmay not be ofcuttings in that ffeatment.No (1) successtulif rooted cuttings also grow slowly. statisticaltests were conductedon the data. Branch-like fbrm is ftequently found in cuttings Rooting was comparedbetween cuttings treated rooted trom woody plants, panicularly ifthe parent with a basalapplication ofStimroot 3 (PlantProd treesare old (Meier-Dinkeland Kleinschmidt 1990, ucts,Bramalea, Ontario), that contained0.87r lBA (indolebutyric Copes1987, Rolund 1979, Black 1972).Because acid) and untreatedcuttings (two parent Pacitic yew parent treesin natural standscan be trees,48 cuttings from each tree in each over 195-years-old(Busing et al. 1995),branch- reatment). (2) Rooting of short (3 to 5 cm) and like fbrm of rooted cuttings could be problem- Iong (25 to 40 cm) cuttings were comparedto atic forplantationestablishment. ln addition,poor determinethe eff-ectsof cutting size (two parent shootgrowth and branch-likeform may lengthen trees,40 cuttings in eachreatment). (3) Effects the time neededto producePacific yew cuttings oftree:rgeuere inrestigatedb1 comparingroot- suitable for outplanting or hedging and reduce ing of rcproductively immature (four trees) and the feasibilitlol a vegetrtireproprgrtion prr. mature(lbur trees)Pacific yew (,18cuttings from gram (Thorpe and Hany 1990). eachtlee in eachtreatment). and (4) Speciesvaia- tion in rooting was comparedbetween cuttings In this study. three elementsof a successtul from Pacificyew andEnglishyew (Ta,rirsbaccara programof Pacilicyeu proprgationwere inres- L.) (two parentffees ofeach species,48 cuttings tigated:(1) Culturalstudies, (2) Rootingstudies from eachparent tree). and (3) Shoetgrowth andorientation studies. The objectiveswere to establishbasic cultural proce- RootingStudies dures for propagatingPacific yew and use them to determinewhether cuttings from either male To assessvariation in rooting betweenmale and or female treesor from different aspects,eleva- female tuees,three sites were selectedon which

Pr,rprgationand Growth of PacificYe$ 57 therewere large ftees of both sexes.Branches from a shadedgreenhouse. They wereted onceweekly one of the sites in the montane (800 m) on with 100ppm20-20-20 (Plant Products, Bramalea, Vancouverlsland were collected in October1993. Ontado) and wateredas required. Height growth Cuttingswere setin earlyNovember and assessed was measuredin Octoberof 1994and 1995.Com- for rooting 6 months later. Experimentaldesign parisonswere basedon nestedanalysis of vari- consistedof tbur replicatesof 150 cuttings (600 ance (Zar 1984) and usedTree(sex) as the error cuttings total) from eachof three male and three term. Plannedconffasts (Mize and Schultz 1985) fcnale treer.Branche. from lhe olhertwo \ile. were madebetween male and female trees(SAS on southernVancouver Island were collected in Institute,V6.0, Cary,NC). Meanswere separated January 1994.Cuttings were set in early Febru using Tukey's StudentizedRange test (HSD; ary 1994and assessedtbr rooting 6 monthslater. p<0.05). Experirnentaldesign consisted of four replicates Shootgrowth orientationwas assessedin Oc- of 20 cuttings (80 cuttings total) tiom each of tober 1995on the sametwo-year-old cuttings as three male and three female treesfrom each lo- were measuredfor height growth. A protractor cation (6 trees).Rooting percentages(percent ot was used to measurethe shoot growth onenta- the total number of cuttings in a replicatewith at tion (90o= vertical). Male and temaletrees were least one root) were transformed (Arcsin) for compared(Table 4) using nestedanalysis of vari- normality (Zar 1984).Comparisons were based ance(Zar 1984)with Tree(sex)as the error term on nestedanalysis ofvariance (Zar 1984)and used (SAS Institute,V6.0, Cary, NC). Meanswere sepa- Tree(sex)as the enor term.Planned contrasts (Mize ratedusingTukey's Studentized Range test (HSD; and Schultz 1985)were madebetween male and p<0.05). femaletrees (SAS Institute,V6.0. Cary, NC). Meanswere separatedusing Tukey's Studentized Resultsand Discussion Rangetest (HSD; p<0.05). To assessgeographic variation in rooting of CulturalStudies six Pacific yew, branches were collected from Rooting hormone (IBA) increasedrooting suc- to rep- naturalstands on VancouverIsland chosen cessfrom 30.60l,to 50.0clr(Table 1). Similar re- (west andwarm resentwet anddry andeast), cool sults have beenfound using IBA with a number (low (nofih and south),and coastaland montane of other yew cultivars (Eccher 1988, Van Hoff setin late andhigh elevation)sites. Cuttings were 1978,Von Komya 1976,Wells 1961).The posi- later. Experi- November and assessed6 months tive rooting responseof Pacific yew cuttings to of l2 mental design consistedof four replicates IBA treatmentindicated that hormonetreatment parcnttree cuttings (48 cuttingstotal) ftom each was important for a successfulpropagation pro- (percent at eachlocation. Rooting percentages of gmm. lt may even be essentialto succassfully the total number ofcuttings in a replicatewith at least one root) were transformed (Arcsin) for TABLE L Summdry ofrooting percentages(1 s.e.)in cul- normality (Zar 1981). Comparisonswere based tural studies.Hormone treamentwas 0.87.18A. and did not on analysisof variance(Zar 1981) in which ltr Juveniletrees were lessthan I m tall skuclures,Mature treeslrcrc within have reproduclive cationswcre blockedand trees were nested more than 5 cm in diametcr and beaing pollen bkrcks.Tree(sex*block) wasused as the enortem. or seed. Plannedcontrasts (Mize and Schultz 1985)were madebetween nofth andsouth, east and west, and E\periment Trealment % Rooted low andhigh clevationsites (SAS Institute,V6.0, + IBA s0.0(6.1) Cary, NC). Means were separatedusing Tukey's H0lmone - IBA 30.6(9.8) StudentizedRange test (HSD; p<0.05). 3-5cm 55.7(6.5) ShootGrowth and Orientation Studies 25 40 cm 50.6(6.8)

ln March of 1994, rooted cuttings from 3 male Age Juvenile 70.8(6.2) (n=101) and 3 femaletrees (n=80) fiom a single Mature 48.6(8.3) VancouverIsland location (Ircn River) weretrans- Spe(ies Pacific yew ,r5.8(5.3) (PSB615,A.45cc) in equal plantedinto sq/roblocks English yew 95.,{(.1.2) partsofpeat, sandand vermiculite and placedin

58 Mitchell root cuttingsfrom somepiuent trees (Loach 1988), tive propagationofEnglish yew (Mitchell1992) as was found in Douglas-fir (Brix 1974). Long may not work as well when they are applied to woody cuttings(37 to 42 cm) rooted successfully rooting Pacific yew cuttings.Nursery ptograms (50.6ola)and at compamblepercentages to short for paclitaxelproduction may also be more suc- (3 to 5 cm) cuttings (55.7016).Successful propa cessful if yew speciesand cultivars other than gation of long cuttings has also been found in Pacific yew are used.Many nursery trials have hardwoodshrubs (Wainwright and Hawkes1988) beendone to improverooting percentages ofother and in Tar,ls (Bell 1975,Wells 1961).Therefore, woody species(Loach 1988)and great gains have long cuttings may be usedto acceleratea propa- been made through such trials (Mendel 1992). gation and outplanting program by producing large Similarexperiments will be neededon Pacificyew treessuitable for outplantingin one lessyear than cuttingsifrooting is to meetexpectations derived if shoficuttings were used (Bell 1975). This would tiom previous studiesof TarrJ. also be of benefit in the establishmentof hedges for paclitaxel production in nurseries. RootingStud es Cuttingsfrom juvenile trees rooted 70.870 while There were no significant differencesin rooting those from sexually mature trees rooted 48.67. percentagesbetween mde andfemale Pacific yew (Table l). This has been found fbr a number of treesfrom the three sitesselected to test for sex- othertree species (Meier-Dinkel and Kleinschmidt specificeffects (Table 2).lnconfast, cuttingsliom 1990,Morgensten et al. 1984,Brix 1974).Rooting female Japaneseyew (Trrrirscuspidata) rooted cuttings from juvenile trees may theretbrc pro- with higher successrates than those from male vide a more efficient way to producelarge num- tlees but differenceswere confoundedby clonal bers oftrees for outplantingthan ifcuttings from effects (Davidson and Olney 1964). Significant maturetrees were used (Thorpe and Harry 1990). rlonal\arialion uas llso.een in thi.erperiment In addition, field performancemay be better in androoting percentagesofindividual parenttrees rooted cuttings from juvenile than mature tees ranged from ahigh of 49.lVo to a low of [.37o (Ritchie1991). The useofjuvenile parenttrees (Table2). Sinceboth maleand female trees rooted would therefore improve the feasibility of both with equalsuccess, vegetative propagation could restorationand paclitaxelproduction programs. provide a viable mears for the conservationof English yew cuttings rooted with higher suc Pacific yew from natural stands. cessIates (95.4olo) than cuttings from Pacific yew Rooting percentageswere not significantly (45.87c)(TableI ). Interspecificdifferences have dill'erentover the six VancouverIsland sites se previouslybeen found in rooting of variousTawt lected to test for effects of geographiclocation speciesand cultivars (Von Komya 1976, Wells (Table3). Rooting percentagesvaried among the l96l). Therefbre,published procedures for vegeta- sites from a low of 30.87oto a high of 66.0%.

TABLE 2 Rooting percentagesof cuttingslrom male (M) and female (F) Pacilic yews from rhreeVancouvcr lsland sites.iRow Means (t nanddrd error, se) followed by the sameletter are no! significantly diffcrent (Tukey's SludentizedRange; HSD, p < 0.05). Maximum and minimum rooting percentageswerc selectedfrom meansof6 parenttrees at eachsitc.

6/r Rooted (se) 7. Rooled (se) 7. Rooted Ma\imum Minimum

RR M l5.8(6.3) a F 38.3(4.8) a 46.3 1.3 RP M l7.s(3.9) a F r9.6(s.7) a 36.3 1.3 IR M 34.5(s.4) a F 19.8(3.3) a ,19.l 6.9

PlannedContrasts

Male vs Female (RR & RP) 0.3921 1.51 0.2536 Male vs Female (IR): o.2216 0.61 0.,1801 rAbbrevialions:RR,Royal Roads; RP, Rocky poinr; IR, IronRiver rlron Riveris tesiedscparaFly because it is geographicallydifferent from lhe oihertwovictoria area sites and because cuttinss weresct 3 monthsearliet |haD rhe orhers.

Propagationand Growth of Pacific Yew 59 TABLE 3. Rooting percentagesofPacific yew cuttingsfrom six VancouverIsland sites.Numberofpdrent trees(N) lion1!\hich maximunr (Max) and minimum (Min) rooting percentageswere selected.Mcans (t standarderror. se) followcd b]_ rhe same letter afe noi significantly dilierenl (Tukcr-'sStudentized Range: HSD. p < 0.05).

Elev. 7. Rootcd (sc)

Harmac (HA) .19"08' 50m 3 66.0(8.5)a 87.5 31.2 Haslam Creek (HC) 49"{13 50m 3 59.0(7.6)a 87.5 san JuaDCreek (sJ) ,18.40', 600m 9 59.7(3..1)a 75.0 25.0 Rooney Lake (RL) 50"21 350n 1 42.1(8.',7)d 60.4 25.0 Jordan River (JR) 48"32' 150m 3 3,1.9(7.5)a 65.0 1.1.6 Tsitika (TS) 50"1.1' ,100m 6 30.8(3.6)a 43.8 11.2.

PlannedContr.rsts df MS

North vs South (cool vr $arm) 0.5940 2.',l6 0.1t22 rHigh vs Low (montanevs coan) 0.0096 0.04 0.8,118 rEastvs Wesi (dry vs rvet) 0.1829 0.85 0.3611

'RL,TS vs JR.HC.HAIrSJ vs JR.HC,HA;TSJ.JR vs HA,HC,TS

Piannedcontrasts between wet and dry sites,cool ond year,height growth increasedover four-fold and warm sites. and coastal and montane sites to an averageof l5.7 cm (Table 4). No signifi showed that there was no significant effect of cant diffgrencesin growth were found between geographiclocation or eievation on rooting de- rootedcuttings from male and fenale treesin ei- spite potential climatic affects on shoot growth ther the fi$t or secondyear after rooting. Clonal and vigour ofparent trees.In Eucalyptus,differ- variation in growth was significant,particularly entecotypes also had rooting percentages that were in the secondyear after rooting when the best not significantly different (Abedini and Marlats clonegrew 31 .2 cm andthe poorest grew 9.7 cm. 1988). Individual Pacific yew parent trees had This is in contrastto Pacificyews in naturalstands rooting percentagesas low as 6.47oand as high where shoot growth tendsto be poor (Busing et as 87.57o.This could be the result ofparent trees al. 1995).There are also indicationsthat rooted beingdill'erent ages. lncreasing age of parenttrees has been found to decreaserooting successand increaseclonal variability (Meier-Dinkel and TABLE ,1. Hcight growth (cm) of rootedcuttings from male Kleinschmidt1990, Thorye and Hary 1990,Black and fcmalc tlees from Iron River in the first 1972)perhrp. throughit' efleclson treerigour (199,{) and second (1995) yean after rooting. (Roberts and Moeller 1978). High vadation in Column means(1s-e.) followed by the samelet- (Tukey rooting among cloneshas also beenobserved in ter are not significantly different s StudentizedRanget HSD, p < 0.05). L(rrix laricina (Morgenstemet al. 1984) and in Douglas-fir (Brix 1974).As a result, large num- Parent Heightgro$th (cm) bers of cuttingsliom parenttrees across a broad Sex Tree 1994 1995 range of sites may be required for a successful (0.2) (0.1)a conseryationprogram, as suggestedby Wheeler Male I 1.1 a 9./ (0.5) (2.6) et al.( 1995).This may limit thenumber ofrooted 4.5 b 31.2 b 3.4(0.4) b I L8 (0.9)a cuttingsthat canbe producedin areasonabletime (Thorye and Harry 1990). 2 2.5(0.3) a 1,1.8(1.4) a 4.3(0.4) b 10.2(1.,r) a (0.6) 16.7(1.4) ShootGrowth and Orientation Studles 1 4.1 b a Male (Average) 3.2(0.4) A 17.5(l.6) A Pacific yew cuttings grew an averageof 3.4 cm Female (Average) 3.6(0.5) A 13.9 .,r)A in the first year after propagation,but in the sec

60 Mitchell TABLE 5. Shool growth orientation (\,er!ical=90")ol two- Footng Studies vear old Pacilic yew rooted cuttings.Mcans l \ e , fnll.\ed h) lhc ,d-e t<|lef]-re nor ,ie- Cuttings from male and female treesrooted equally nilicantly different (Tukey's S!udcnlizedRanger weli andcuttings from all parenttees ftom 6 sites HSD. p < 0.05). on VancouverIsland were successfullyrooted. This is an essentialelement ofa yegetativepropa- Sirc Sex Age Parent No. of Ofientation gationprogram aimed atgenetic conservation and Trees Cutlings habitatrestoration. Significant clonal variationin M.rle 2 101 55.8'(2..1)a rootrng percentagesindicated that some parent trcesmay be Female 2 80 s2.4"(l.s) a diflicult to rcot andimplied thar large numbersof cuttingsfiom eachtree would be r\bbrc\ialion:lR; Iron River neededfor a r iableregerrrive propagrlion pro gram. ShootGrowth and Orientation Studies cuftingsmay not grow aswell asseedlings (futchie and Long 1986).Planting trials will be neededto Rootedcuttings grew well in the nurserybut two testwhether good growth ratesin the nurserywill yearswere requiredto producetrees tall enough be canied to the field. All the rootedcuttings had to plant.All the cloneshad branchJite shootgrowth branch-like form (Table 5). No significant dif- orientationand this may be problematicfor sur- ferenceswere tbund betweencuttings from male vival and growth during the outplantingphase of and female treesand the averageangle of shoot a Pacitic yew conservationprogmm. Field trials growth was 5,1.1' from horizontal. Branchlike of Pacific yew rooted cuttings are neededto test form is not uncommon in cuttings rooted liom whether the good growth rates achievedin the woody plants, particularly if the parent hees are nurserywill continue ard whether branchlike form old (Meier-Dinkeland Kleinschmidt 1990,Copes rs penlstent. 1987,Black 1972).This condition would tend to The successof vegetative propagation and compromisethe survival of cuttings planted on subsequentgood growth ratesof rooted cuttings sites where competing vegetationis a problem lrom Pacilic1eu indicatedthar genetic re\ource\ fbr seedlingestablishment. Such sitesoccur fre- of natural standscould be conservedusing that quently in the VancouverIsland Region (Koppenaal approach.Studies are now under way to deter- and Mitchell 1992).An upright form may be re- mine the toleranceof Pacificyew to exposureand gainedin time (Thorpe and Harry 1990,Rolund droughtand to measurethe succassofoutplantings 1979) and it may be possible to promote it by on disturbedsites. Those studies will providefur- stakingthe trees. ther indicationsof whether a Pacitic yew man- agementprogram basedon vegetativepropaga Summaryand Conclusions tion is viable. Culturalstudies Acknowledgements Pacific yew can be propagatedusing published The author thanksT. Bown, K. Hogg, R. Hagel, techniquesfor other Zlra.r speciesbut expecta- R. Rowswell and G. Roke (Pacific ForestryCen- tions of rooting succassmay not be met. Further trc) and D. Pigott (Yellow Point Propagation)for experimentsare neededto increaserooting per- theirvaluable contributions. This studywas funded centagesof Pacific yew so that sufficient num- in part by the ForestryCanada Science and Tech- bersofrooted cuttingscan be producedtbr a suc- nologiesOpportunities Fund and the GreenPlan cessfulconservation program. National ForestGenetic Resources Centre.

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Received21 Februan l996 Accepted2l September1996

ProDasationand Growth of Pacific Yew 63