LIBRO-CONGRESO-CITRUS

furanocoumarins. However, a particular hybrid between ‘Chandler’ pummelo X ‘Orah’ mandarin, named
‘Aliza’, had low furanocoumarin content. At the same time, the observed level of naringin, which provides
typical grapefruit bitter flavor, in ‘Aliza’ fruit was the same as that detected in ‘Marsh’ grapefruit.
S02O11
Genotypic variation of rind colour in citrus tangor ‘Kiyomi’ progenies
Combrink N.K. 1 , Bijzet Z. 1 , Sippel A.D. 1 , Booyse M. 2 , and Labuschagne M.T. 3
1 Agricultural Research Council - Insitute for tropical and Subtripical Crops (ARC-ITSC), Plant Improvement, South Africa; 2 Agricultural
Research Council - Biometry (ARC-Biometry), Biometry, South Africa; and 3 University of the Free State (UFS), Plant Breeding, South
Africa. combrinkn@arc.agric.za
Rind colour is the most important characteristic contributing to a fruit’s appearance and therefore the
improvement of rind colour has been a longstanding aim of citrus breeding programmes. However, due to the
lack of information on the inheritance of rind colour in citrus, the breeder faces a difficult task when planning
crosses for breeding new cultivars. By quantifying the variation in a population the breeder can study the
relationships between the hybrids and parents and gain an understanding of how certain characteristics are
inherited. Therefore a study was undertaken to investigate the variation in rind colour, as chroma coordinates
L*, a* and b*, in six mandarin families, where female parent ‘Kiyomi’ tangor (Citrus unshiu x Citrus sinensis)
was crossed with male parents ‘Dancy’, ‘Hansen’, ‘Rishon’, ‘Roma’, ‘Shani’ and ‘Sunburst’ mandarins (Citrus
reticulata). A significant level of variation was found between both the parents and the families for all the
colour coordinates. A greater variation was found within the families than between the families, indicating a
high level of genetic variation within the families, while the within tree variation was lower than the within
family variation. All the families showed an improvement in the population for rind colour over the female
parent ‘Kiyomi’ for L* and b*, while all the families except for the ‘Kiyomi’ x ‘Dancy’ family showed an
improvement for a*. The ‘Kiyomi’ x ‘Dancy’ and ‘Kiyomi’ x ‘Roma’ families were found to have a population
with a lighter, more yellow-orange rind colour, while the ‘Kiyomi’ x ‘Hansen’, ‘Kiyomi’ x ‘Rishon’, ‘Kiyomi’
x ‘Shani’ and ‘Kiyomi’ x ‘Sunburst’ families had a population with a deeper, more orange-red rind colour.
The intraclass correlation coefficient relevant to selection within the families was fairly low, indicating the
variation was only partly genetic and the environment contributed to the phenotypic variation. Therefore a
mean performance of multiple year’s data should be used for effective selection.
S02O12
Rootstock effects on mandarin fruit traits under control and salinity conditions
Raga V. 1 , Bernet G.P. 1 , Carbonell E.A. 2 , and Asíns M.J. 1
1 Instituto Valenciano de Investigaciones Agrarias (I.V.I.A.), Centro de Protección Vegetal y Biotecnología, Spain; and 2 Instituto
Valenciano de Investigaciones Agrarias (I.V.I.A.), Biometría, Spain. raga_ver@gva.es
The objective of this study is to explore rootstock genetic effects on salt tolerance in terms of fruit yield.
A seedling population from hybrids between Citrus volkameriana (V) and Poncirus trifoliata (P), and its
grandparents (V and P) were grafted with ‘Hashimoto’ mandarin. Trees were maintained in a screenhouse and
salt treatment (25 mM NaCl) was applied from June to September for 5 years (2004-2008) to 32 genotypes
and 18 controls. Rootstocks were genotyped for 5 salt tolerance candidate genes. Alleles of 96 and 73 markers
segregating at the V and P genomes, respectively, in the VxP nucellar seedlings were studied for marker-trait
associations. Significant effects for rootstock genotype (G) and treatment (E) were found for most traits.
Salinity decreased yield and juice volume, but improved total soluble solids and rind thickness. Year effects
were highly significant in most cases. GxE interaction was found for fruit weight, total fruit weight, leaf water
content and leaf [Na]. Trait heritabilities of rootstock effects ranged from low to very low and no fruit yield
trait had consistent, significant correlations through years with any non-fruit trait. Two salt tolerant candidates
were associated with fruit yield traits, but only under control conditions. Segregations at 8 and 9 loci on the V
and P genomes, respectively, were highly associated with fruit yield under the salinity treatment. Therefore,
phenotypic selection assisted by markers linked to these QTL is more efficient than just phenotypic selection
to obtain rootstocks that confer salt tolerance to the grafted mandarin.
XII INTERNATIONAL CITRUS CONGRESS 2012 - 41
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