of China Australia Food Security Cooperation Initiative (CAFSCI)

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Evaluation of East Asian citrus germplasm as scions and rootstock

Overview of Project

The specific objectives of the project were: to collect and exchange citrus rootstocks, clones, public access hybrids and species native to each country (Vietnam, China and Australia); to cooperate in the evaluation of citrus rootstock material including germplasm characterisation, assessment of tolerance to pathogenic and environmental stresses, and assessment of horticultural potential; to collect and exchange citrus scion germplasm of economic significance to each country; to assess, improve and maintain the health status of citrus scion germplasm; to investigate the feasibility for citrus seed introduction and the reduction of the juvenile period to provide fruiting wood (in comparison to the time taken for budwood introductions to be available for trial); to establish source trees of important new citrus scion cultivars in each country.

Key Outcomes of Project

The project successfully fostered the exchange of citrus rootstock and scion germplasm between Australia, China and Vietnam for the benefit of citrus improvement programs in each country and promoted the further collection and conservation of native germplasm in China and Vietnam. The subsequent screening of accessions for horticultural performance, salt tolerance and disease tolerance identified important sources of variation in key attributes relevant to current rootstock improvement programs.

Training programs have been highly effective in broadening the scope of citrus improvement programs in both China and Vietnam and in promoting the wider use of rootstocks to improve orchard productivity

Virus-free budwood of 20 public-access varieties was supplied to Vietnam from Australia along with seed of commercially important citrus rootstocks. Seeds of 13 citrus species and hybrids were supplied to China from germplasm collections in Australia together with budwood of public-access navel orange clones. In all, a total of 47 new accessions have been introduced into China. Forty-four new scion and rootstock accessions were introduced as seed into Australia from Vietnam and 35 accessions from China, including seeds from crosses made in China to investigate salt tolerance in Poncirus trifoliata. Along with the rootstock material introduced during the first project this represents a unique germplasm resource which will be of considerable long-term benefit to citrus improvement programs in Australia and internationally throughout the region.

Screening experiments conducted in Australia for Phytophthora, CTV, salt tolerance and early indications of graft incompatibility demonstrated wide variability among accessions. New salt accumulating and excluding germplasm was identified. Zaoyang zhi, a P. trifoliata accession from China has shown no indication of yellow-ring incompatibility (a major problem in commercial lemons) with Eureka lemon in early screening trials, and has great promise as an alternative replant rootstock for Eureka lemons.

Nine replicated preliminary field screening trials have been successfully established in Australia to assess horticultural performance and disease and salt tolerance of rootstock accessions under field conditions. Trials of Valencia orange, Navelina, Lane Late navel, Imperial mandarin, Eureka lemon and Fino lemon scion cultivars are revealing differences among accessions in effects on initial yield and yield efficiency relative to tree size. The field screening trials are being conducted as part of the National Citrus Rootstock Screening Program with funding support from Horticulture Australia.

The marketing period for citrus in China has traditionally been quite short but the introduction of new citrus varieties has served to extend the supply period and boost the industry. Among the introduced cultivars Lane Late navel has been extensively propagated and 100,000 trees planted in south China. "

Project Dates

01 Jul 1997 - 30 Jun 2007


Southern Fruit Research Institute - Vietnam
Research Institute of Fruit and Vegetables - Vietnam
Chinese Academy of Agricultural Sciences - China
CSIRO Plant Industry - Australia


Dr Ken Bevington



03 5019 8431