IntroductionPeach production is an important industry in various partsof the world, and considerable research effort has beentargeted at breeding and cultivation. However, ourknowledge of optimal techniques for the production ofinexpensive planting material suitable for high densityorchards is scarce.

Production costs and the short commercial life of peachcultivars, have directed attention to production systems thatproduce high yields early in the life of an orchard. Forexample, high density planting has advantages overtraditional systems because labour costs are reduced and thepotential for mechanisation of harvesting is improved.However, high density planting systems involve higher initialcosts in orchard establishment, because a larger numbers ofyoung trees are required (Chalmers et al. 1978; Erez 1976,1978). In vitro propagation has been successful with somerootstocks, but few cultivars have successfully completed therooting or acclimation stages. In contrast, 13 to 90% rootingof softwood cuttings of different cultivars has been reported(Arye and Zieslin 1974; Kosina 1989; Sharpe 1956).Successful rooting of semi-hardwood cuttings of somecultivars and rootstocks has also been reported (Arye andZieslin 1974; Coston et al. 1983; Couvillon and Erez 1980;

Marini 1983). Bartolini et al. (1979b) noted great variabilitybetween 3 peach cultivars when using hardwood cuttings.Propagation by root cuttings has had only limited use, but itcould be valuable in propagating cultivars with low rootingsuccess (i.e. hardwood or semi-hardwood cuttings) and inrescuing material after loss or damage of the aerial parts innon-grafted plants. Successful regeneration from rootcuttings has been achieved for aspen (Eliasson 1961;Johanson and Lundh 1988), for raspberry (Heuser 1977), forapple (Robinson and Schwabe 1977), for kiwi (Lawes andSim 1980) and for sandal (Uniyal et al. 1985). Thecommercial use of this technique for apple varieties grownon their own roots was investigated by Robinson andSchwabe (1977). They showed that if scion varieties aregrafted onto known rootstocks, the propagation of the latterfrom root-shoots may have advantages over the presentmethod of stool beds.

The aim of this study was to investigate the possibility ofpropagation peach trees using root cuttings. In addition,attempts were made to increase the percentage of sproutingon root cuttings by cold storage, hormone application andx-ray treatment. Separate experiments were also conductedto manipulate carbohydrate supply to the root cuttings by‘lung shoots’.

Australian Journal of Experimental Agriculture, 2006, 46, 1091–1095

0816-1089/06/08109110.1071/EA04147© CSIRO 2006

C. G. TsipouridisA,C and W. W. SchwabeB

APomology Institute, Naoussa, 59200, Greece.BWye College, University of London, Ashford, Kent TN25 5AH, UK.

CCorresponding author. Email: tsipouco@alfanet.gr

Abstract. This study showed that shoot cuttings collected from peach trees in February and November gave thehighest sprouting percentages. A comparison of 3 cultivars of Prunus persica L. Batch (ArmKing, Early Crest andMay Crest) showed that November sampling was optimal for all cultivars. Although the sprouting of root cuttingsgave much lower percentages, the peak values occurred at exactly the same times of year as those for root formation.The results also showed that the effectiveness of indole-butyric acid treatment to induce root formation on detachedroot-shoots was greater when the seasonal rooting level is low. However, this inverse correlation is not significantwhen all 12 monthly values are combined. The data for comparing the 2 rootstocks and their interaction with theconcentration of benzyl-adenine-purine applied showed that St Julien GF655/2 (Prunus insititia) had moreproductive root-shoots and better growth than Damas GF1869 (Prunus domestica × Prunus spinosa). There was nosignificant difference between different concentrations of benzyl-adenine-purine, but benzyl-adenine-purineaffected the morphology of the young root-shoots. Cold storage for 1 month had a beneficial effect on sprouting ofroot cuttings of the rootstock GF677 (Prunus persica × Prunus amygdalus) and treatments with bottom heatincreased sprouting over that achieved in the growth room. X-ray treated roots produced significantly fewer sprouts.

Additional keywords: cytokinin, root cuttings, x-ray.

Studies on the regeneration of peach cultivars and rootstocks fromroot cuttings in comparison with aerial cuttings

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C. G. Tsipouridis and W. W. Schwabe1092 Australian Journal of Experimental Agriculture

Materials and methodsShoot cuttingsShoot cuttings were taken from 5-year-old parent trees, originallyderived from hardwood cuttings, comprising the cultivars Early Crest,May Crest, ArmKing and the peach rootstock GF677. A total of150 shoot cuttings (each 20 cm long) was taken from all cultivars androotstock at monthly intervals from January to December. Anydiscoloured, blemished or diseased shoot cutting was discarded. Thebases of these cuttings (according to season either softwood, semi-hardwood or hardwood cuttings) were treated for 15 s with indole-butyric acid (IBA) in a 50% ethanol solution (quick dip) at 0, 1000 and2000 mg/L. After drying, the cut surfaces were treated with Captan(75%, 1:9 in talc). The cuttings were then inserted in sand on rootingbenches with bottom heat using thermostatically controlled heatingcables, which maintained a temperature of 18–20°C during the periodfrom l October to 30 May. Automatic misting was controlled by anartificial leaf sensor. Cuttings were sprayed with Benlate and thenRovral once a week.

Root cuttingsFifty root cuttings of cultivars Early Crest, May Crest and the peachrootstock GF677 were taken at the same dates as the shoot cuttings.They were cut to 20 cm in length, with a mean diameter of 0.8–1.2 mm,washed and surface dried (paper towels) and their orientation marked.Any discoloured, blemished or diseased root cutting was discarded.Their proximal ends were given a 15 s dip in a 1000 mg/L solution ofbenzyl-adenine-purine (BAP) made up in a small amount of ethanol andthen diluted in distilled water. After drying, the cut ends were treatedwith Captan (75%, 1:9 in talc). The cuttings were then planted(proximal end up) in sand in a vertical position with 4 cm protrudingabove the surface. Temperature conditions and anti-fungal treatmentwere similar to those described above.

Roots of the rootstocks St Julien GF 655/2, Damas GF 1869, GF677and cultivars Early Crest and May Crest were obtained from5–6-year-old experimental trees that had been uprooted. The rootcuttings, 0.5–2.0 cm in diameter and 20 cm in length, were prepared asdescribed above, but they were then planted either horizontally inPerlite, l cm below the surface and watered, avoiding water-logging, orthey were planted vertically in sand as described. Visible bud swellingand their polar distribution along the length of the cutting were recordedafter specified periods followed by measurements of number and lengthof root-shoots (longer than 1 cm) Such shoots were then detached. Thiseliminated inhibitory effects due to apical dominance and a secondflush was allowed to develop on the same roots.

Other treatmentsIn a treatment designed to promote shoot proliferation, wet roots wereplaced in polythene bags and kept in a refrigerator at 2–4°C for1 month. Cuttings were then planted horizontally in wet Perlite inwooden boxes, which were transferred into a growth room at 25 ± 1°Cand 80% RH and placed next to the unchilled controls. Others wereinserted vertically in sand on the bottom heat bench (see above).

For the cytokinin treatment, root cuttings of the rootstock GF677were immersed for 6 h in 0, 40, 80, and 160 mg/L BAP, plantedhorizontally in Perlite and transferred to the growth room, which had a16 h photoperiod (daylight fluorescent lamps).

For the x-ray treatment, which was used as an anti-auxin measure,150 root cuttings of 1-year-old plants of GF677 were given a 15 s quickdip in a 1000 mg/L solution of BAP, treated with Captan (75%) at thecut ends and then exposed to x-ray radiation for 0, 5, and 20 s (at adosage of V = 80 kW, and I = 400 mA). They were then planted in sandto a depth of 16 cm, with 4 cm protruding above the surface.

Root-shoot cuttingsIn December 1990, hardwood cuttings were taken from shoots (root-shoots) developed on root cuttings of the rootstock GF677 (planted

vertically in sand 1 or 2 years previously). The bases of these shootswere either in the air or, in another batch, below the surface (a fewhaving developed 1 or 2 roots). These root-shoots were cut at 10 cmlength, their base and dipped for 15 s in IBA (2000 mg/L in a 50%solution of ethanol) and the bases treated with Captan (75%). Forcomparison, similar hardwood cuttings were taken from 5-year-oldparent trees. There were 5 replications of 10 cuttings for each treatment.Results were collected 30 days after planting.

Experimental design and analysisRandomised blocks or simple factorial designs were used in theanalysis of individual experiments. The limited supply of suitable rootmaterial restricted the number of replications in some experiments.

ResultsSeasonal effectsSummarising the data from all cultivars, there appears to be3 peaks of rooting over the calendar year. Shoot cuttingscollected in February and November gave the highest rootingpercentages, with the peach rootstock GF677 reaching 80%for the February set and over 90% in November (Fig. 1). Thethird peak was lower and occurred in mid-summer (June formost cultivars and August for GF677). The Novembersamplings were optimal for all cultivars (Fig. 1).

Although the sprouting of root cuttings gave overall muchlower sprouting percentages than the shoot cuttings (Fig. 2),the peak values occurred at exactly the same times of year asthose for root formation, which suggests that there may be acommon factor influencing the different processes.

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Fig. 1. Seasonal rhizogenesis in GF677, Early Crest, May Crest andArmKing shoot cuttings sampled at monthly intervals. Each plottedvalue is the mean of 50 cuttings.

Australian Journal of Experimental Agriculture 1093

The effectiveness of IBA treatment in inducing rootformation on detached root-shoots is much greater when theseasonal rooting level is low, e.g. rooting is increased by2.8 times relative to the control by 1000 mg/L treatment inJanuary. However, this inverse correlation is not significantwhen all 12 monthly values are combined (y = 12.4 – 76x, r= 0.266, P>0.05). The data for comparing the 2 rootstocksand their interaction with the concentration of BAP appliedare shown in Table 1. In all 3 comparisons St Julien GF655/2is more productive at the generation of root-shoots and theirgrowth than Damas GF1869. There was no significantdifference between different concentrations of BAP, but BAPaffected the morphology of the young root-shoots.

No root-shoots were obtained from the peach rootstockGF677 and the cultivars Early Crest and May Crest. A furtherexperiment with these cultivars and similar treatments atmonthly intervals until 4 May again failed to give anypositive effects.

Cold storageThe effect of cold storage for 1 month on the sprouting ofroot cuttings of the rootstock GF677 was beneficial

(Table 2). Treatment with bottom heat also increasedsprouting above that achieved in the growth room.

X-ray treatmentThis treatment was used to reduce residual internal auxin inthe root cutting and, thus, permit more sprouting. However,x-ray-treated roots produced significantly fewer sprouts thanuntreated roots.

DiscussionKnowledge about vegetative propagation in peach trees hasbecome important because of the greatly increased quantitiesof planting material required for early cropping and denselyplanted but short-lived orchards. The present studies wereconfined to methods of producing rooted cuttings largelyfrom roots in comparison with aerial shoot cuttings.Although it is noted that cutting quality and behaviour is alsoaffected by numerous factors such as soil conditions and thestate of the mother plant (Hoad 1978), these aspects have notbeen studied. However, it has now been established thatpeach cultivars and rootstocks can easily be regeneratedfrom root cuttings, in particular cv. Early Crest and the peachrootstocks St Julien GF305, Damas GF 1869 and GF677.The feasibility of using adventitious shoots produced onroots is already known, e.g. for apple, sandal and aspen

Regeneration of peach stocks and root cuttings

Table 1. Shoot production, length of root-shoots and sprouting of root cuttings after 60 days in growth room

Values are the average of 24 cuttings. Values followed by different letters are significantly different (P = 0.05)

Rootstocks BAP application rate (mg/L) Mean l.s.d. (P = 0.05)0 40 80 160 Cultivar BAP Cultivar × BAP

Shoot production (per 20-cm root cutting)St Julien GF655/2 4.80ab 5.40a 2.80ab 2.80ab 4.00a 1.1 1.9 3.7Damas GF1869 1.80b 2.50ab 3.10ab 2.30ab 2.40bMean 3.30a 3.95a 2.95a 2.55a

Length of root-shoots (cm)St Julien GF655/2 7.70a 8.20a 8.20a 7.60a 7.90a 2.2 3.4 7.6Damas GF1869 3.20a 2.40a 2.60a 4.00a 3.10aMean 5.50a 5.30a 5.40a 5.80a

Sprouting of root cuttings (%)St Julien GF655/2 58.30a 58.30a 45.80ab 54.20ab 54.20a 8.9 12.6 26.4Damas GF1869 29.20b 41.70ab 33.30ab 37.50ab 35.40bMean 43.80a 50.00a 39.60a 45.90a

Table 2. Effect of cold storage and orientation of GF677 root cuttings, treated with 1000 mg/L BAP

on sprouting (no. of sprouts)

Values are means of 40 cuttings. Values followed by different lettersare significantly different (P = 0.05)

Treatments OrientationHorizontal Vertical

Control A (fresh-bottom heat) 17b 11a1 month chilling and bottom heat 28a 16aControl B (fresh-growth room) 0d 0b1 month chilling and growth room 8c 4bl.s.d. (P = 0.05) 7.80

Table 3. Effect of an entire shoot allowed to grow on the cutting(with or without buds) on new shoot production of root cuttings,

for the second year of their establishment

Values are not significantly (P = 0.05) different

Treatments No. of sprouts

Control (root cuttings without shoot) 0Root cuttings with 1 shoot 0Root cuttings with 1 shoot but without buds 4l.s.d. (P = 0.05) 4.52

C. G. Tsipouridis and W. W. Schwabe1094 Australian Journal of Experimental Agriculture

(Eliasson 1961; Johanson and Lundh 1988; Robinson andSchwabe 1977; Uniyal et al. 1985). The advantage ofnumbers of shoots not being restricted to performed budinitials and the prolonged period of productivity of roots areclearly beneficial.

As was expected, there are marked differences betweencultivars and rootstock of peach, e.g. St Julien GF655/2rooted easily although another rootstock Damas GF1869 wasless able to do so. However, it is clear from the experimentsdesigned to optimise conditions for adventitious shootformation, that there is still considerable scope to obtain ahigh degree of proliferation over a prolonged period on suchroots. A period of chilling proved to be an effective methodof increasing shoot production (Table 2). The plantingmethod of the root cuttings indicated that vertical plantingwas less successful than horizontal planting below thesurface of the substrate (Table 2). Again, the physicalconditions were clearly of importance, with bottom heatbeing beneficial (Table 2). The mechanism and causes ofsome of these effects will require further exploration. Inanalogy to results in apple (Robinson and Schwabe 1977), itseems very likely that internal carbohydrate levels, as well asauxin contents, could play a significant role in peach.Bartolini et al. (2000) reported that there was a goodcorrelation between rooting success and carbohydratecontents. Chilling may have led to hydrolysis ofpolysaccharides, increasing available hexose levels. The factthat there were marked seasonal differences in shootingpercentage would point in this direction. Bartolini et al.(1979a) reported effects of sampling date of tree rooting ofcuttings of peach cultivars with cold requirements. It wasalso worth noting that there seemed to be a similarity ofseasonal changes in root cuttings and aerial material (Figs 1and 2). Another aspect of the use of root cuttings asproducers of root-shoots, is the capacity for producing suchadventitious shoots and the survival of the root cutting itself.Robinson and Schwabe (1977) reported that these roots(30 cm long) could produce up to 10 or more root-shoots andproliferation could be greatly enhanced by treating the rootwith immersion in a cytokinin solution. In peach, such atreatment did not promote significant proliferation, althoughperhaps other cytokinins could have been tested.

The death of some root cuttings could be related toexhaustion of their carbohydrate content (Hartmann andKester 1975) and further investigation should be conductedin this area. If 1 leafy root-shoot was left on the root cuttingits survival was insured, but apical dominance exerted bysuch a shoot would then prevent further proliferation.However, if such a ‘lung-shoot’ was itself decapitated and itslateral buds removed, the root could be kept alive and wasable to produce more adventitious shoots. However, eventualleaf fall ended the system, i.e. renewal of ‘lung shoots’wouldbe needed. Possibly the system could be continued if 1 of thesprouted shoots, the second year was decapitated and itsbuds were removed. This was also true for peach (Table 3).

The subsequent rooting of the detached root-shoots(using the conventional auxin treatments) proved to berelatively easy compared with the rooting of aerial shoots, ashad also been reported for apple. However, the differences inthe type of shoots produced above the substrate (i.e. in thelight) and the almost 100% rooting of root-shoots whosebases had been below the substrate before detachmentindicated an important effect (Table 4).

It may, therefore, be concluded that production of peachplants or rootstock material from root cuttings is a feasibleand relatively rapid and convenient method of raisingplanting material. Equally, it may be feasible to obtain root-shoots by cutting old trees in orchards to ground level andusing the shoots produced on their roots as a ‘stool bed’ fornew hardwood cuttings with perhaps 30–50 cuttings per tree,or again, orchards may be ‘renewed’ by grafting on suchroot-shoots.

AcknowledgmentsWe would like to express our thanks to the staff of PomologyInstitute, Naoussa for their assistance with conducting theexperiments.

ReferencesArye YO, Zieslin N (1974) Mist propagation of peach and almond ×

peach hybrids. Scientia Horticulturae 3, 369–382. Bartolini G, Bellini E, Messeri C (1979a) Influence of sampling date of

the rooting of cuttings of peach cultivars with different coldrequirements. Rivista della Ortoflorofrutticoltura Italiana 6,343–355.

Bartolini G, Bellini GE, Messeri C (1979b) Indagini sulle cause divariabilita della CA-PACITA rizogena nelle talee di alcune cultivardi pesco. Rivista della Ortoflorofrutticoltura Italiana 6, 423–434.

Bartolini G, Pestelli P, Tazzari L, Toponi MA (2000) Parameters thatinfluence rooting and survival of peach cuttings. Journal ofAmerican Pomological Society 54, 183–188.

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Table 4. Rooting of detached root-shoot hardwood cuttings,treated with 2000 mg/L IBA

Values are means of 40 cuttings. Values followed by different lettersare significantly different (P = 0.05)

Origin of hardwood cuttings Cuttings with roots (%)

Root-shoot (with their bases in substrate) 96aControl (from trees) 26bRoot-shoot (from aerial bases) 34bl.s.d. (P = 0.05) 14.50

Australian Journal of Experimental Agriculture 1095

Eliasson L (1961) The influence of growth substances on the formationof shoots from aspen roots. Physiologia Plantarum 14, 150–156.

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Received 29 July 2004, accepted 15 March 2005

Regeneration of peach stocks and root cuttings

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