Pg. 35-37 ITSG-Lietsjieteelprogram

Die plaaslike lietsjieteelprogram wat bestaan uit oop-, self- en kruisbestuiwing, het ‘n aanvang geneem gedurende die 1992/93 – seisoen en ongeveer 3 000 sade van verskillende bestuiwings is reeds in ‘n kwekery uitgeplant. Om die lang jeugfase van lietsjiesaailinge te verkort is daar begin om ringelering, ombuig van saailinge, groeireguleerders, snoeimetodes, droogtestres, bemesting en enting op die proef te stet. Hierdie manipulasie van saailinge word gedoen op 2 000 saailingbome wat geplant is in 1990/91. Verskeie kombinasies van belowende kultivars en seleksies is oorgewerk/geent vir gekontroleerde self- en kruisbestuiwings en verdere kombinasies is gedurende 1994 oorgewerk op volwasse bome op die ITSG se Friedenheim Proefplaas. Die genebron wat bestaan uit 13 kultivars en 10 seleksies, is uitgebrei met die toevoeging van die kultivars Sovey Tung, Haak Yip, Kwai May Pink, Salathiel en Wai Chee. Namate nuwe belowende kultivars beskikbaar word, sat dit ingevoer en by die genebron gevoeg word. Die ITSG beplan om jaarliks minstens 1 000 saailinge uit die teelprogram te vestig. Sodra die eerste van die saailinge in produksie kom, sal daar jaarliks minstens 1 000 saailinge beskikbaar wees vir evaluasie.

Die doel van hierdie projek is om lietsjiekultivars vir Suid-Afrikaanse toestande te teel/selekteer wat die beperkte kultivarreeks en keuse kan uitbrei om die kort produksieseisoen te rek. Produktiewe kultivars met ‘n goeie kleur, vruggehalte, houvermoe, bestandheid teen siektes en plae asook die beperking van alternatiewe drag, is verdere doelstellings wat nagestreef word.

Summary:

• The local litchi breeding program started in the 1992/93 season with over 3,000 seeds from various pollinations planted in the nursery.
• Techniques to reduce the long juvenile phase of litchi seedlings are being trialed, including girdling, bending seedlings, growth regulators, pruning, drought stress, fertilization, and grafting on 2,000 seedling trees planted in 1990/91.
• The gene pool at ITSG includes 13 cultivars and 10 selections, recently expanded with cultivars Sovey Tung, Haak Yip, Kwai May Pink, Salathiel, and Wai Chee; new promising cultivars are imported as available.
• Several promising cultivar and selection combinations have been top-worked and grafted onto existing rootstocks, with plans for more in 1994.
• The program aims to establish at least 1,000 seedlings annually for evaluation and production.
• The goal is to breed cultivars suitable for South African conditions, extending the limited cultivar range and harvesting season, with traits like good color, quality, shelf-life, pest and disease tolerance, and reduced alternate bearing.
• Litchis have been grown in South Africa for over a century, but mainly two cultivars dominate; the short harvest season is a limiting factor.
• There has been no dedicated breeding program in South Africa before; this program addresses that gap with controlled open, self, and cross-pollinations.
• The breeding program uses molecular genetics and biotechnological techniques such as iso-enzyme analysis and Random Amplified Polymorphic DNA (RAPDs) for parentage determination and genetic marker identification.
• The breeding program phases include initial seedling establishment, primary evaluation based on yield and fruit quality, followed by multi-site climatic evaluation, and semi-commercial evaluation in collaboration with growers.
• Over 2,000 open- and self-pollinated seeds from various cultivars and selections were planted recently, with controlled crosses already made, e.g., between Third Month Red and Mauritius selections.
• Tree top-working reduces problems with large tree size and facilitates controlled pollinations.
• The juvenile phase of litchi seedlings can last 5-10 years; the program is testing various techniques to shorten this.
• The program plans long-term development of improved cultivars adapted to local conditions rather than relying solely on imported cultivars.
• The South African Litchi Growers Association is acknowledged for financial support.