Copyright is owned by the Author of the thesis. Permission is given for a copy to be downloaded by an individual for the purpose of research and private study only. The thesis may not be reproduced elsewhere without the permission of the Author.
sor.rn FAC'J'ORS WHICH 1,iAY I1'FLUENCE
R001.' FORMATION IN CONIFER
CUTTil:GS
A Thesis Submitted in Partial Fulfilment of the Req_uirements for the Degree of
~aster of Horticultural Science at
r,'fassey University
CLAIRE ALICE BASHAM 1981
ACIUWWLEDGE~,:ENTS
·~~ ......
I wo~ld like to thank my SJpervisors Dr D. J.
Woolley and, during the initial stages of the study, Dr D.
s.
Tustin. In addition, thanks are extendedto: the New_Zealand Nursery Research Centre for the provision of stock plant material and use of their nursery facilities; Kessrs D. Anderson and A. Watson for technical advice; Ralta Ltd for the gift of an electric cable; Plant Physiology Division, D.S.I.R., for the use of erowth cabinet facilities.
ABSTRACT
Seasonal fluctuations in adventitious root formation capacity of cuttings of Juniperus virginiana L. 'Skyrocket'
("easy-to-root") and J. scopulorwn Sarg. 'Pathfinder' ("difficult-to-root"), as indicated by three parameters,
1 was determined over a nine month period from late summer (February) until spring (October). Rootability rose from a low or moderate level in late swnmer to an optimum in mid winter after an intervening period of low potential
and diminished again in spring. A less comprehensive
study of Cupressus sempervirens L. 'Swane' s Golden' (tteasy-to- root11) revealed that rootability was high in February and June but low in March. The most marked difference in the
pattern of seasonal chs.nges between the two juniper•
cultivars occurred in the percentage of cuttings rooted,
which increased dramatically in~. virginiana 'Skyrocket' in April and remained at high levels before declining sharply in October but remained low in cuttings of
~- scopulorum 'Pathfinder' until the optimum was attained suddenly in June and dimini.shed thereafter. Generally more gradual changes occurred in the other parameters.
Air temperature treat~ents of the ?tock plants and cuttings induced significant differences in level of rootjrtg ·achieved in cuttings taken in mid winter.
Material of J. virginiana 'Skyrocket' arid !I_. scopulorum 'Pathfinder' from stock plants which had received norm.al
winter chilling had a greater root regeneration potential than
that from pl':tnts maintained in a he&ted cln::rnhouse since at.1tur.rn. The converse was trt.1e fo1· cuttings of
;r_.
sco:>ulorum' Blue Haven' ( ''very diffi ct.11 t-to-root") and Q.. semoervirens 'Swane's Golden'. 1'he effect of cutting environment was rather more variable but material which had been exposed to the most favourable parent environment tended to root in greatest numbers in an unheated cor.1pared with a heated air environr.1ent. Responses of
;r_.
scooulorum 'Pathfinder' andg_. senrnervirens 'Swane' s 3-olden' t.111der control-led environment .growth cabinet cor1di tions confiri':'led. •J
these results. The attainment of a high rooting percentage in cuttings of~- Ecooulorum 'Pathfinder' in mid winter
appeared to be de 0endent to a large extent on exposure of tl1e stock pl2nts to l ow te~peratures. Results from the seasonal study ~enerally coincided with the com~only held opinion that phase·, of-growth ma;y be an important determinant of root formation potential in narrow-leaved evergreens. It was suggested that the p1•omotion of rootin[ in chilled material
of
;r_.
virkiniana ' Skyrocket' ond J. scooulor~~ 'Pathfinder'may have been associated with the stimulation of shoot activity brou[).t about by t}12t treati-:ient but there was no conclusive evidence to su,port -'-' Lfl l . ~ •
Analysis of endogenous cr owt11 PeL:ilst or content wa6 conducted in material fro~ ~ifferent c~ltivars, te~peraLt.1re
pro~oter seemed to be tiie l esst rc.loted to oiffer·ences in rootability. r:stimated J..E.4. e;:d total c,ytoki11in conter:t, appeared to be inversely related to root8bility i n several instances.
rr ADLE OF cc;:-rr:?~1'S
ACKNO~"JLEDGP~I~ r:T S ABSfRACT
1 • H~l'rtOLJCTIO!J
1 .1 Introduction to the Present Investi~ation 1 .2 Description of the Cultivars
2. REVIEW OF LI'I'ERA'l'Ullli
2 .1 Seasonal Fluctuations in Rooting Capacity
2. 2 Envir·onmental Factors In:fluencing Root Formation 2. 2 .1 Photoperiod
2.2.2 Light Intensity and Quality 2.2.3 ~emperature
2.2.4 ::oisture
2.3 Otter Factors 2elated to the Selection and Treatment of Llaterial
2. 3 .1 2.3.2
Juvenility
Other Cuttins CharEcteristics 'l'Le Presence of Buds and Leaves Additional Cutting Treatments
2.4
Growth Regulators, Cofactors .and Nutrients 2 .4 .1 ~uxins2 .4. 2 Gibberellins 2.~.3 Cytokinins 2. }~ • 4 AbsciEic .Acid 2.4.5 Eth,ylene
r , I I'"
~ • 4• L) Cofe.cto1·s 2.4.7 :;utrients
3. ::J..T"cRI.AL2 A;T' :'hr;iO:J:-'
3.1 So.1rce, Pre;,areti c,n B!i.'."~ rrt·::.·Lr,ent of Cutti11g
~-: a teri a 1
3 • 1 • 1 Seu son a 1 St u d,y
3 .1 • 2 Growth Cabinet Study 3 .1 . 3 ··id ·,-.,inter St udy
Page
1
2
4
9
1 2
15
20
22
23
25
26
27 29 30
33
~ ,.
_)O
40 41
3. 2 Endogeno;.1s Growth Reru.l stor· Analyses 3.2.1 Extraction and Initial Purificati on 3. 2.2 Paper Chromatography
Auxi ns and Acidic Inhibitors Butonol-Sol uble Cytokinins 3.2.3 Bioa.ssays
4 .
Illi SULT~.Avena Coleoptile ~ioassay Triticum Col eoptile 3ioassay Radish Cotyle1on Bioassay
4 .1 SeDsonnl 3tc1dy
Page
44
46 47 47 48 49
4.1.1 J . virginiana ' Skyrocket ' 51
4.1 .2 J. scooulorum ' Pathfinder ' 59
4 .1 • 3 Com_peri son of ~. virgini ana ' s:kyr-ocket' and
J . scopc1lorum 'Pathfinder' 61
4.1 .4 C. semoervirens ' Swane' s Golden' 62
4.1 .5 SubEeqc1ent Growth of 2ooted Cuttings 64
4.1.6 Swnr:Hn·y of SeEJsonal ·1'rends
4.2
Growth Cebinet St.1ay4. 2 .1 ;£. sco 8.1lorw11 'Pa t11finder'
4.2.2 ~- sempervirens 'Swane' s 3olden' 4 • 2 • 3 S WTL.1le-r y
4-3 ~id ~inter Study
4. 3 .1
4.3.2 4.3.3 4. 3 .l..j 4.3.5
J. virginiana 'Skyrocket'
;r_. sc ooulorurn ' Pathfinder '
.J. sco ::iulorum ' Blue n aven'
C. ee~pervirens ' Swane' s Golden'
Co'.il:Jc.rison of ?ara;r:et ers of :<ootin~ and 5.nd :3hoot G1·owtr1
4. 3 • 6 S U:f.ffif.I',Y
4.4 Growtll Reculato1· Analyses 4.L].1 J..uxin
4 • Lj I • c ,,._
4-~-3
Growth Ini·Jitit.ory J,.ct.ivity Cytokinin Activity
5. Disc;_;s::rc::
5.1 See.sonal 7luctuations i n r-:oot Fori:lation Potential
65 67 70 70
75
89 92 97
100 100
1 02 104 106 1 O[,
11 C
5.2 Air Temperature rreatment
5.3 Endogenous Growth Regulators
5 . 4
ConclusionAPP11IDICES
1 • Buffer Solutions St&.ndar·d Curves 2.
3.
4.
Analysis of Variance for the Seasonal Study
Analysis of Variance for the Growth Cabinet 3tudy
5. AnEilysis of Variance for the ~,'.id ·:.inter Study 6. Relationships between Parameters in J. virginiana
' Skyr·ocket'
7. Chro:natogram of Acidic Growtr-1 Reculators
B.
Chromatogram of ~ytokinin ActivityLITERATURE CITED
Page
1 20 1 27 130
LIST OF FI3:JRES
Figure Page
1. Seasonal fluctuations in mean number of
i•
' Skyrocket' andi•
'Pathfinder' cuttings rooted 54 2a. Seasonal fluctuations in the mean nlli~ber of rootsper· cut ting of
i •
'Skyrocket' and ~' 'Pathfinder' 55 2b. SeasonEt.l f luc tua t ion~. in ;11een nu:Tiber of roots perrooted c~tting of~- ' Skyrocket' and
i•
'Pathfinder'56
3a. Seasonal fluctuations in the mean total root length per cutting o:f J. ' Skyrocket' and i• 'Pathfinder' 57 3b. Seasonal fluctuations in the mean total root length
per rooted cutting and mean root length of
i·
' Skyrocket' andI·
'Pathfinder~(a-c). Varie.tion in a) mean nwnber of cuttings rooted, b) wean number of roots per cutting and c) mean
total root length per cutting of C. ' Swanes Golden'
58
with month of excision. 63
5(a,b) . Growth cabinet stc1dy. Variation in mean nwnber of a)!I. 'Pathfinder' and b) ~. 'Swanes Golden'
cuttings rooted with air temperature treatment.
6(a,b). Growth cabinet study. Variation in mean nmnber of roots per cuttine: of a) J. 'Pati,.finder' and
71
b) C. ' Swanes Golden' with a1r te:nperature treatmeI1t 72 7(a, b) . Growth cabinet stud::,-. '.Tar-is.tion in :nean total
root leneth per cuttine and ,.ear. r oot length of a)
i•
' ?athfinder' aud t) C. ' c:wane-s 3olden' with air· te.-nr,erature treet,lient- ' )
o,a-d • Variation in mean nc1mber of a) ~- ' Skyrocket', b) ~' 'Pathfinder', c) !I• ' Blue Haven' and
d) C. ' Swanes Gol~en' cuttings rooted with air te~perature treat~efit
73
79
?igure Page
9(a-d). Variation in mean nwnber of roots per cuttins of a) iI,. 'Skyrocket~ , . b_) J. 'Pathfinder' ,
c) J. ' Blue Haven' and d) C. 'Swanes Golden' with air temperature treetment
1O(a-d). Variation in mean total root length per
cutting and mean root length of a) il.• 'Skyrocket' , b) J . 'Pathfinder', c) il.· 'Blue Haven' and
d) C. 'Swanes Golden' with air te~perature treatment
11 (a-c). Variation in mean nwnber of cuttings of a) J. ' Skyrocket', b) ~- 'Pathfinder' and
c) J . ' Blue J-laven' showinc active shoot growth with air teu:;ier·aturE- tr·t=·at:nent
12 (a-c). Variation in mean shoot ~rowth per c~tting of a)~- ' Skyrocket', b) ~- 'Pathfinder' and
81
83
85
c) J. ' Elue Haven' v,i tli air tenperature trertt::nent 87 13. Levels of an IAA-like growth 0romoter detected in
c~ttinc tissue from different so~rces 103
14. Levels of an ADA-like growth inhibitor detected in
cutting tiss;ie from different sources 105 15. Level s of total cytokini n ectivity detected in
107
LJ2.1' OF 'T'ADLES
Table Page
1 (a-c). Variation in a) mean number of cuttings rooted b) mean number of roots per cutting and
c) mean total root length per cutting of
J. ' Skyrocket' and J . 'Pathfinder' wi tli month of excision
2(a,b). Variation in shoot activity of~- 'Skyrocket'
and
-
J. 'Pathfinder' cuttin~ .::-s at liftin~ cr asindicated by a) mean n,nber of cuttings showing new shoot gro~th and b) mean shoot crowth per c~1ttirie: v,ith month of excision
3(a-c). Variation in a) mean number of cuttings rooted b) mean number of rooLs per cutting end
c; menn total T·oot lenzth ~er cc1ttin[ of G. ' cwanes Golden' with :non th of excision
4. Variation in mett11 hei3J1t above ~oil level of rooted cuttinGS with month of excision
S(a-c). Growti1 cabinet study. Var·iation in rooting of J. '?atl1fi11der' cuttir:[:E ,vi tJ1 air temperatur·e trE-P. t:,;ent
6(a-c) . ~ro~th cabinet study. Variation in rooting of
tr•f:.' t= t.T:eL t
7 / . 1. a-c 1' . ~:id wi.'1te:r> st.1dy. 'lariatior1 in e) mean nurr;ber of cL1ttings rooted, :-•; mean nur.lber of roots per
cuttin[ and c) ~ean tot~l root len2th per cutting
52
59
64
63
of '-' . ' 3;;::yr·ocket' vii th air te,Ti_pe-r·aure ti·eetment. 76
fable
0(a,b). ~.'.id winter study. Vuriation in a) mean n:imber of cuttings showi~g new shoot growth and
b) mean shoot 5rowU1 per cuttin£ of J. ' Skyrocket' with air temper8ture treatment.
9(e-c). 1.~ id winter stldy. Var•i u ti on in a) mean number of c..itti11£S rooted, b) mean nwnber of roots per c..itting and c) ~ean total r·oot lencth per cutting
Page
77
of J . ' Pathfinde~' with air te~Jerature treatment 90 1O(a,b). 1/id winter study. Variation in~) mean number
of cuttings showing ne½ shoot srowth and b) mean shoot erowth per cutting of
J . 'Pathfinder' witll air te,::perature treat:i,ent 91 11 (a-c) . :.:id wi nter Etl1dy. Variation in a) mean number
of cuttinss rooted, b) mean nun1ber of roots per cutting ehd c) mean total root length per cuttin;
of J. 'Blue Heven' with air temperature tre&t~ent 93 12(a.,b). ::id winter stuoy. Variation in a) mean number
of cuttings showing ner.- shoot growth and b) mean shoot growth per cutting of~- ' Blue
Haven' with air te~perature treat~ent 94
13 (a-c). :.:i d IVint er st,1c1y. \-Eri ati on in & ) ;.1ean nwr,ber of cuttin[S rooted, b) Liean number of rooLs per cuttin[ and c) iTiean totc.l root l enctl1 pe1· c--1ttinc of' (; . ' ~:wene-s ·Jolde11' ,·,i U1 air· tt::Tipereture
tr·eet:::ent
LIS r OF PLA1'E S
Plate Page
1. A propagation tray used for the provision of basal heat to cuttings in the growth cabinets 42
2. Photographic representation of the mean nwnber of J_.
sc oo u, lo rwn
'Pathfinder' cuttings rooted aft er 10 weeks after exci .sion in April, June andAugust. 60
3. A saTiple sbowin[; the ran[:e of root for:nation
obtained over all temperature treatments 10 weeks_ after- excisio_n- of
;r.
virginiana ' Skyrocket'6u~tings in mid winter .
4. A sample sl10wL'1g the range of root formation
obtained over all te;nperature trestme11ts 10 weeks after excision of ;; • scoo ~101.·um 1 3L.le F even '
cutti~gs i.:1 mid winter.
5. A sa:1ple fhowinz: ti1e ran.e;e of root formati on
obtained over all Lemper ature treatments 10 weeks after excision of J . scopul orum 'Pathfinder'
C i.l t tin~ S .
6. A. sample sho·t:ing the range of r·oot for-ma tion
obt2ined over ell t.r..:>.-:-:;,eI.·e.t..;.re ~;·t'r,"-:..,,c11ts 10 v.reeks
3fter excision of r: . sccnervi1'ent3 ' Sv.anes Golden' cutti~ss in mi j Ki~~er .
99
99
Abbreviations
Mid Winter Study
Parent ~aterial ~reatmen~- ',i'P = "warmparent"
·,yep = 11 warm+cold parent 11
CP = 11 cold ;iar·en t 11
CCP
=
"cold+cold parent"Cutting T1·e&t:;-ients
~7H = "war;n propagation house"
CH n
=
"cold propsgetion h o,1se"Gro~th Cabinet St~~Y
PareDt ~ateriel Treat~ents
i'✓P = "war-:r. parent"
CP = "colcJ pa1·ent11
Cuttinr; Tre2t;nents .vn = "warm propaggtion
house''
CH= "cold propag&tion ho!.1.se"
-, parent plsnt held in a heated e;l asshouse ( 1 8 °c) from au tu.mn
= as for fi? plus two weeks winter chilling prior to excision
= parent pl&nt exposed to normal winter chilling
= as for CP pl us two weeks cool-
st .rage (5°c) of cuttin£ m3.terial
= cJttings propagated in a heated
( -0 ) 1
; l asshouse 10 C over basa heat
= cuttinfs propagated in an ~nheated glasshouse (approx. 13°c) over basal heat
= parent plE.tJJtE' ;nai ntained in £
1:c,r.:: environme11t (2cf'c)
= p2.l'ent plonts naintained in n cold environment ( 1 o0c)
= c·uttings prope~ated in R we.rm
environment (18°c) over basal heat
= cuttings propas&ted in a cold enviPonment ( 1 2°c ). over basal h.ea t
,,
CHAP1'ER 1
I:NTRODUC'l'ION
1 .1 Introduction to the Present Investigation
A vegetative means of propagating certain plants is frequently desirable or necessary and for this purpose
1 •
the use of stem cuttings is normally the preferred and certainly the most extensively applied method. · The
utilization of this .importaht means of propagation is often seriously hampered however by a low ability of cuttings of many species to form adventitious roots or by large
variations in this ability.
Most species exhibit a degree of seasonal variation in their capacity to root from cuttings and root initiation potential of conifers is often greatly influenced by factors associated with season or state of growth. Adventitious root formation is a complex phenonmenon involving-inter- actions of many environmental and endogenous factors not yet clearly understood although such an understanding could be of great assistance in overcoming some of the
difficulties encountered in practice. Research .conducted at the New Zealand Nursery Research Centre, Pa~merston North, indicated that air temperature at both the stock plant and cutting stages may significantly a~fect rooting of certain conifer species. The present study was therefore under-
taken to investigate:
i) seasonal fluctuations in root formation ability,
ii) the effects of air temperature at the parent material and cutting stages on rooting of the cuttings,
iii) levels of certain endogenous growth regulators in relation to capacity to form roots
in easy- and difficult-to-root conifers and to determine possible relationships between these.
1 .2 Description of the Cultivars
Four cultivars were used in the study: Juniperus virginiana L. 'Skyrocket' syn
I•
scopulorum Sarg.2.
'Skyrocket' ("easy-to-root"); I· scopulorum Sarg. 'Pathfinder' syn J. virginiana L. 'Pathfinder' ("difficult-to-root");
J. scopulorum Sarg. 'Blue Haven' syn 'Blue Heaven' ( "very difficult-to-root"); Cupressus sempervirens L. 'Swane's Golden' ("easy-to-root").
The junipers form a very large and important genus from which which a great many cultivars are derived.
J. virginiana (eastern red cedar or pencil cedar) and J. scopulorum (Rocky Mountain juniper) are native to eastern and western North America respectively. Ident-
ification of these genetically diverse species is difficult and many hybrids occur between these and other species. The two species are closely allied and some authors believe
that
I•
scopulorum may be only a subspecies of~- virginiana. Although both have given rise to many highly valued ornamental cultivars, these hardy species
'
3.
are of commercial value in other respects. J. virginie.na for instance is used in its country of origin for timber, essential oils and windbreaks, and ultimately· forms a large tree. (Bailey, 1928; Haverbeke and Read, 1976).
~- virginiana 'Skyrocket' is of a very narrow, columnar growth habit, with grey-green foliage and :has a rather fast rate of growth in comparison with most junipers.
J. scopulorwn 'Pathfinder' and J. scopulorwn 'Blue Haven' have blue-grey foliage and are of upright, ·pyramidal growth habit. All have predominantly scale-like leaves although foliage of juvenile, more open appearance is commonly found scattered throughout the plant. A height of approximately 2 - 2.5 mis reached after ten years. Propagation is
normally from cuttings except in J. scopuloum 'Blue Haven' which is reported to be grafted in most instances
(Harrison, 1975; Bloom, 1972; Proudley, 1977).
The cypresses are valued ornamentals in mild climates and C. sempervirens (Italian cypress), as the common name
indicates, originates from southern Europe.
c.
sempervirens 'Swane's Golden' is a slow growing yellow-gold form.ofnarrow, columnar growth habit and is normally propagated by cuttings_(Harrison, ·1975; Proudley, 1977).
