Tree training and managing complexity and yield in fig (Ficus carica L.)

Thesis (MscAgric (Horticulture))--University of Stellenbosch, 2010.

ENGLISH ABSTRACT: Commercial fig production with popular European cultivars, Bourjasotte Noire, Col de Damme Noire and Noire de Caromb, is new to the Western Cape. Little research on fig production has been conducted in South Africa and producers are struggling to implement effective commercial practices. In order to establish practices that will maximise yield of quality fruit, the most productive one-year-old shoot lengths were identified in a phenological study. All shoot length categories evaluated in ‘Bourjasotte Noire’ (10 – 15 cm, 25 – 40 cm, 50 – 65 cm, 75+ cm) yielded fruit and will probably yield well the following season. In ‘Col de Damme Noire’, shoots longer than 60 cm seem to be suited to reproduction, yet they might produce a poor yield the following season. Shoots 10 – 20 cm long in ‘Noire de Caromb’ are productive relative to their length, while shoots 30 – 50 cm and 60 – 80 cm long are also fairly productive. Shoots longer than 100 cm produced suitable shoot lengths for yield the following season. Two experiments were conducted on ‘Bourjasotte Noire’ and ‘Col de Damme Noire’ to establish the type (Experiment 1, different intensity heading cuts) and timing (Experiment 2) of pruning cuts required to stimulate the growth of shoots of the same length as the shoots selected to be optimal for yield in the phenology study, and to reduce the expression of distal branching. In ‘Bourjasotte Noire’, removing one third of the total length of one-year-old shoots on 21 July by heading stimulated the development of more growth and longer current season shoots compared to other treatments, while reducing yield slightly. Heading back to three nodes in ‘Col de Damme Noire’ stimulated the growth of current season shoots of the optimal length established in the phenology study, while heading cuts on 30 June produced the longest average current season shoot length in ‘Col de Damme Noire’. To further address the effects of distal branching (acrotony), an experiment was conducted to establish whether rest breaking agents (RBA’s) in combination with tip-pruning can increase tree complexity by improving bud break, and whether increased complexity would increase yield in all three cultivars. A second experiment was conducted to evaluate the effects of timing RBA applications on bud break and harvest scheduling. Lift® increased the number of buds breaking in ‘Bourjasotte Noire’, while in ‘Noire de Caromb’ Dormex® and oil increased bud break. Tip-pruning increased the average shoot length in ‘Bourjasotte Noire’ and ‘Col de Damme Noire’, while causing a reduction in the amount of new growth in ‘Noire de Caromb’. Lift® applied 3 August and Dormex® applied 30 June shortened the number of days to 50% bud break in ‘Bourjasotte Noire’ and ‘Col de Damme Noire’. Both Lift® and Dormex® applied on 30 June decreased the number of days to 50% bud break and 50% harvest of the breba crop in ‘Noire de Caromb’. These treatments increased the number of fruit in both the breba and main crop of ‘Noire de Caromb’, but reduced fruit size. In conclusion, different approaches with regards to pruning needs to be followed for each cultivar to establish or maintain the optimal shoots for reproduction, while RBA’s can be used to force earlier, increased- bud break and harvest of breba fruit.

AFRIKAANSE OPSOMMING: Kommersiele verbouing van drie Europese vykultivars, Bourjasotte Noire, Col de Damme Noire en Noire de Caromb is nuut tot die Wes-Kaap. Baie min navorsing oor die verbouing van vye is al in Suid-Afrika gedoen, met die gevolg dat produsente sukkel om effektiewe kommersiële verbouingspraktyke te implementeer. ‘n Fenologiese studie van die drie kultivars is uitgevoer om vas te stel wat die mees produktiewe een-jaar-oue lootlengte is, met die doel om die opbrengs van kwaliteit vrugte te maksimeer. Al vier kategorieë wat ge-evalueer is in ‘Bourjasotte Noire’ (10 – 15 cm, 25 – 40 cm, 50 – 65 cm, 75+ cm) is gevind om geskik te wees vir huidige en volgende seisoen opbrengs. Lote langer as 60 cm is geskik vir opbrengs in ‘Col de Damme Noire’ in die huidige seisoen, maar mag in die volgende seisoen swak presteer a.g.v. die gebrekkige lengte van nuwe lote wat daarop ontwikkel. In ‘Noire de Caromb’ is gevind dat lote 10 – 20 cm lank baie produktief is relatief tot hul lengte en dat lote 20 – 50 cm en 60 – 80 cm lank ook relatief produktief is. Lote langer as 100 cm was minder produktief, maar het nuwe lote gelewer wat geskik is vir opbrengs die volgende seisoen. Twee snoei eskperimente is uitgevoer op ‘Bourjasotte Noire’ en ‘Col de Damme Noire’ om vas te stel wat die mees geskikte tipe snoeisnit (Eksperiment 1, verskillende dieptes van topsnitte) en tydstip om te snoei (Eksperiment 2) is met die doel om lote te produseer soortgelyk in lengte aan die wat in die fenologie studie uitgewys is as die produktiefste, en om moontlik die voorkoms van “kaalnekke” te verminder. In ‘Bourjasotte Noire’ is gevind dat die wegsnoei van ‘n derde van die loot op 21 Julie aanleiding gee tot meer groei, langer een-jaar-oue lote en ‘n effense afname in opbrengs. Geskikte lote langer as 60 cm kan in ‘Col de Damme Noire’ verkry word deur lote te top sodat net drie nodes oorbly. Die uitvoer van topsnitte op 30 Junie het langer gemiddelde lootlengtes tot gevolg gehad. Om die probleem van “kaalnekke” (apikale dominansie) verder aan te spreek, is ‘n eksperiment uitgevoer om vas te stel of rusbreekmiddels gekombineerd met tip-snoei gebruik kan word om kompleksiteit te vermeerder deur knopbreek te verhoog, en indien wel, of dit sal aanleiding gee tot verhoogde opbrengs in al drie kultivars. ‘n Tweede eksperiment met verskillende toedieningstye van rusbreekmiddels is uitgevoer om vas te stel of oeste geskeduleer kan word. Lift® het knopbreek verhoog in ‘Bourjasotte Noire’, terwyl Dormex® en olie knopbreek verhoog het in ‘Noire de Caromb’. Tip-snoei het die gemiddelde lootlengtes verhoog in ‘Bourjasotte Noire’ en ‘Col de Damme Noire’, terwyl dit groei verminder het in ‘Noire de Caromb’. Lift® toediening op 3 Augustus en Dormex® toediening op 30 Junie het die aanvang van 50% knopbreek vervroeg in ‘Boujasotte Noire’ en ‘Col de Damme Noire’. Beide Lift® en Dormex® toediening op 30 Junie het die bereiking van 50% knopbreek- en 50% oes vervroeg in ‘Noire de Caromb’. Hierdie behandeling het ook die aantal vrugte van die breba- en hoofoes vermeerder, maar vruggrootte verminder. Verskillende snoeibenaderings behoort dus gevolg te word om vir elke kultivar die regte lootlengtes te genereer of te onderhou, terwyl rusbreekmiddels gebruik kan word om knopbreek te vervroeg en verhoog, en om die breba oes te vervroeg.

Masters