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dc.contributor.advisorBothma-Schmidt, A.
dc.contributor.advisorEngelbrecht, G. M.
dc.contributor.authorVan Zyl, L. C.
dc.date.accessioned2016-01-12T09:28:56Z
dc.date.available2016-01-12T09:28:56Z
dc.date.copyright2008-04
dc.date.issued2009-04
dc.date.submitted2009-04
dc.identifier.urihttp://hdl.handle.net/11660/2145
dc.description.abstractEnglish: One of the biggest constraints to the expansion of the walnut industry in South Africa, is the availability of good quality and cost effective plant material. Since walnuts are more difficult to propagate vegetatively than most fruit and nut species, controlled conditions are required to ensure grafting success. Hot callus grafting is a bench grafting procedure subjecting grafted trees to controlled, elevated temperature and humidity, and has been implemented successfully in several countries to increase grafting success of walnut. Until now, hot callus grafting has not been investigated as a possible walnut propagation method in South Africa. The present study assessed method of heat supply and time of grafting, as important factors determining grafting success of two walnut cultivars grafted onto Juglans regia rootstocks under hot callus conditions. Although neither method of heat supply provided definite superior grafting success, localized heating of graft unions in a heated trench, gave more consistent results than heating the entire grafted tree in a heated room. Both methods seemed promising, since acceptable grafting success was obtained in some instances with both the heated trench and room. Post-grafting shoot growth on the other hand, was significantly higher for the heated trench than for the room. Both methods did, however, result in trees of a suitable size for orchard establishment after only one growing season. Results further indicated that exposure to increased temperature for a period of 25 days is more than sufficient for callus development of walnut, and very little is gained by heating grafted trees for longer. Earlier grafting, before the onset of bud break of cultivar and/or rootstock, generally resulted in improved grafting success and drastically increased shoot growth during the first growing season, providing grafted trees of saleable size in a shorter time. There were no clear differences regarding callus formation, grafting success or survival between the two cultivars evaluated, ‘Chandler’ and ‘Serr’. As expected, more vigorous post-grafting growth was observed for ‘Serr’, since it is the more vigorous grower of the two. A separate hot callus grafting trial, using Paradox rootstocks, also indicated that the type of rootstock utilized in hot callus grafting may impact grafting success. More consistent results were obtained with all four cultivars grafted onto this hybrid rootstock, than with J. regia rootstocks in the preceding trial. For both J. regia and Paradox rootstocks, survival of trees through the first growing season was still unacceptably low, although results were comparable to that of other studies. Since results were available for a single season only, conclusions should be regarded as preliminary. Nevertheless, findings clearly illustrated the potential value of hot callus grafting as propagation method for walnut in South Africa and lay a foundation for the establishment of propagation guidelines using this approach.en_ZA
dc.description.abstractAfrikaans: Een van die grootste beperkinge tot die uitbreiding van die okkerneutindustrie in Suid-Afrika, is die beskikbaarheid van goeie kwaliteit en koste effektiewe plantmateriaal. Aangesien dit moeiliker is om okkerneute vegetatief te vermeerder as die meeste ander vrug- en neutspesies, word beheerde toestande benodig om suksesvolle enting te verseker. Warm kallus enting is ‘n tafelenting prosedure waar geënte boompies aan beheerde, verhoogde temperatuur en humiditeit onderwerp word. Dit is reeds suksesvol geïmplementeer in verskeie lande om die sukses van okkerneut enting te verhoog. Warm-kallus-enting is nog nie voorheen as ‘n moontlike vermeerderingsmetode vir okkerneute in Suid-Afrika ondersoek nie. In hierdie studie is die metode van verhitting en tyd van enting, as bepalende faktore wat die sukses van warm kallus enting van twee okkerneut kultivars op Juglans regia onderstamme beïnvloed, geëvalueer. Gelokaliseerde verhitting van die entlas in ‘n voortjie, het meer konsekwente resultate gelewer as verhitting van die hele geënte boom in ‘n kamer, alhoewel nie een van die metodes opvallend beter was as die ander nie. Beide metodes blyk egter belowend te wees, aangesien kommersieel-aanvaarbare ent sukses verkry is met beide die verhitte voortjie en - kamer onder sekere toestande. In teenstelling hiermee, was lootgroei na enting betekenisvol hoër vir gelokaliseerde verhitting in die voortjie as vir die kamer. Beide metodes het egter bome van aanvaarbare grootte vir boordvestiging na slegs een groeiseisoen opgelewer. Resultate het verder getoon dat ‘n verhittingsperiode van 25 dae meer as voldoende was vir kallusontwikkeling by okkerneute, en dat geen addisionele voordeel verkry is deur die geënte bome vir ‘n langer tydperk te verhit nie. Vroeër enting, voor die aanvang van bot van die kultivar en/of onderstam, het ‘n toename in ent sukses bewerkstellig en ook lootgroei in die eerste groeiseisoen drasties verhoog, om sodoende bome van aanvaarbare grootte in ‘n korter tydperk te lewer. Daar was geen duidelike verskille tussen die twee kultivars, ‘Chandler’ en ‘Serr’, wat geëvalueer is nie, behalwe vir lootgroei na enting. Soos verwag, het die sterker groeier, ‘Serr’, betekenisvol beter groei getoon as ‘Chandler’ in die eerste groeiseisoen. ‘n Verdere warm kallus eksperiment met Paradox onderstamme, het aangedui dat die tipe onderstam die sukses van enting moontlik kan beïnvloed. Meer konsekwente resultate is verkry met al vier die kultivars wat op hierdie onderstam geënt is, in vergelyking met J. regia onderstamme in die voorafgaande proef. Die oorlewing van geënte bome, op beide J. regia en Paradox onderstamme, was steeds onaanvaarbaar laag teen die einde van die eerste groeiseisoen, alhoewel die resultate vergelykbaar was met ander soortgelyke studies. Aangesien resultate van slegs een seisoen beskikbaar was, moet afleidings as voorlopig beskou word. Nogtans het bevindinge die potensiële waarde van warm-kallus-enting as ‘n vermeerderingsmetode vir okkerneute duidelik geïllustreer en ‘n grondslag is gelê vir die daarstelling van vermeerderingsriglyne deur hierdie benadering in Suid-Afrika.af
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectDissertation (M.Sc.Agric. (Horticulture))--University of the Free State, 2008en_ZA
dc.subjectWalnut -- Grafting -- South Africaen_ZA
dc.subjectWalnut -- Propagation -- South Africaen_ZA
dc.subjectCallus developmenten_ZA
dc.subjectParadox rootstocken_ZA
dc.subjectPost grafting growthen_ZA
dc.subjectGrafting timeen_ZA
dc.subjectHeated roomen_ZA
dc.subjectHeated trenchen_ZA
dc.subjectHot callus graftingen_ZA
dc.subjectPersian walnuten_ZA
dc.subjectPropagationen_ZA
dc.titleGrafting of walnut (Juglans regia L.) with hot callusing techniques under South African conditionsen_ZA
dc.typeDissertationen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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