New Chinese rootstocks for Australia: Aug 2017

Dr Tahir Khurshid has been leading the final stages of a NSW DPI rootstock project that spanned 20 years.  These new rootstocks will provide Australian citrus growers with more rootstock options to suit specific environments and improve orchard productivity.

The work was a collaborative effort between NSW DPI, CSIRO and research partners in China and involved co-funding partnerships with Horticulture Innovation Australia and The Australian Centre for International Agricultural Research (ACIAR).Primary ­Industries Minister Niall Blair and NSW DPI citrus researcher Dr Tahir Khurshid inspecting fruit of a new Chinese citrus rootstock

The rootstock varieties were sourced from a native citrus arboretum in China in the 1990’s. The rootstocks were screened in the laboratory and greenhouse to assess their resistance to Phytophthora collar rot and Citrus tristeza virus, bud union compatibility to common Australian scion varieties and salt tolerance.  The rootstocks were planted in field trials at NSW DPI Dareton and for the past 20 years Dr Khurshid and his team have been assessing the performance of these rootsocks with Navelina, Imperial mandarin, Lane Late navel, Eureka lemon and Valencia scions.

Two mandarin and four trifoliata type rootstocks performed better than current Australian rootstocks or exhibited special characteristics (Table 1). Further assessment of the selected six rootstocks will be expanded to twenty grower properties in different citrus growing regions throughout Australia. Rootstock seed can be purchased from Auscitrus (03) 5027 4411.

Table 1. Chinese rootstocks characteristics as compared to Tri22

Name

Zao Yang

Tanghe

Ghana

Donghai

Anjiang hongju

Caoshi xiangju

Type

Poncirus trifoliata

Poncirus trifoliata

Poncirus trifoliata

Poncirus trifoliata

Citrus erythrosa (mandarin)

Citrus erythrosa (mandarin)

Compati-bility

No incompatibility with Eureka to-date

Excellent with all scions tested

Excellent with all scions tested

Variable

Variable

Variable

Vigour

Similar

Less than, might be suitable for high density planting

Similar

Less than, might be suitable for high density planting

More than, might be suitable for medium to low density planting

More than, might be suitable for medium to low density planting

Yields

Higher for Navelina  and Valencia

Above for all scions tested

Above for all scions tested

Higher on Valencia

Higher for Valencia

Higher

Fruit quality

Higher for Valencia and similar for Navelina

Slightly larger fruit size for Navelina and Lane Late

Similar internal quality to all scions tested. Smaller fruit size for Navelina and bigger for Lane Late and Imperial Mandarin

Smaller fruit for Valencia and Navelina. Sweetness is better than Tanghe for Navelina

Internal quality acceptable for Valencia and higher for imperial mandarin

Internal quality acceptable for Valencia

Disease

Highly resistant to CTV, Phytophthora collar and root rot

Highly resistant to CTV, Phytophthora collar and root rot

Highly resistant to CTV, Phytophthora collar and root rot

Highly resistant to CTV, Phytophthora collar and root rot

Resistant to CTV and is moderately resistant to Phytophthora

Moderately resistant to Phytophthora root rot

Special

Excludes sodium and flowers later

Excludes sodium

Excludes sodium and accumulates chloride

 

Excludes sodium and chloride, suited to shallow and sandy soils

Excludes sodium and chloride. deep-rooted suited for deep sandy soils

Suggested scions

Valencia and Lane Late navel

Valencia and Lane Late navel

Navel oranges and Imperial mandarin

Valencia and Navelina

Lane Late and Imperial mandarin

Valencia