LIBRO-CONGRESO-CITRUS

S17O06
New promising citrus hybrids for the ornamental use
Recupero S., Russo G., and Reforgiato Recupero G.
CRA- Centro di Ricerca per l’Agrumicoltura e le Colture Mediterranee (CRA-ACM), Italy. giuseppe.reforgiato@entecra.it
In Italy for the production of ornamental citrus lemon (Citrus limon), ‘Oval’ kumquat (Fortunella margarita),
‘Calamondin’ (C. madurensis) and ‘Small leaf’ chinotto (C. myrtifolia) represent the most utilized species.
Considering that the market offer is increasing also in others competitor’s countries, there is the risk of a
surplus of production. So is very important for revitalizing the market the availability of new genotypes. In
2002 the CRA-ACM started a breeding program with the intent to produce new genotypes with favourable
and variable ornamental traits. Two new genotypes showing interesting ornamental characteristics recently
released are reported. The former is a hybrid obtained by cross of ‘Meyer’ lemon and a blood orange, showing
original striped fruits as an apparent form of orange-over-red periclinal chimera. In 2012 this genotype was
proposed for the Italian patent. The latter is a chance seedling of ‘Oval’ kumquat, showing small, rounded,
yellow and very fragrant fruits. Due to its late blooming fruits persist on the trees until the late summer, when
other genotypes are not able to maintain fruits on the tree.
S17O07
‘Meirav’ seedless, a new promising Israeli mandarin: effects of rootstocks and growth regulators
on yield and fruit quality
Kanonich Y.K., Holsman S.H., Oren Y.O., Kaplan I., Tagari E., Fainzack M., and Giladi B.
Ministry of Agriculture Extension Service, Israel. shukan@shaham.moag.gov.il
‘Meirav’ seedless mandarins naturally ripen from December till late January. The fruit are entirely seedless,
have an attractive orange/red color, and are very tasty and easy to peel. The variety was tested during 4
consecutive growth seasons for yield, fruit size and quality on 4 different rootstocks: ‘812’, sour orange, ‘C-35’
and ‘Volkameriana’ in two different climates in the desert and coastal areas. The rootstocks ‘812’ and sour
orange were most preferred regarding their effects on fruit quality. In the desert area, TSS and acid levels on
‘812’ and sour orange rootstocks were ~12.0% and ~0.85%, respectively, and the annual average yield was 39
ton/ha. ‘Volkameriana’ rootstock provided a higher average yield of 58 ton/ha, but fruit internal quality was
poor, and TSS and acid levels were just 10.9% and 0.7%, respectively. In the coastal area, ‘812’, sour orange
and ‘C-35’ rootstocks had more or less similar effects on yield (3.8-4.1 ton/ha), TSS (13.6-13.7%) and acidity
levels (0.94-1.08%). However, the ‘C-35’ rootstock caused severe scion-rootstock incompatibility observed
already after 7 years. Double sprays with Naphthalene acetic acid (NAA, 300 mg/L) combined with ‘Bonus-
NPK’ fertilizer (4%) on medium size fruitlets (16 and 20.5 mm in diameter), did not affect fruit thinning, but
significantly increased fruit size and consequently total yield. Overall, our data suggest that ‘812’ and sour
orange are the preferable rootstocks for ‘Meirav’ seedless mandarin due to their positive effects on yield and
fruit quality. NAA treatments further increased fruit size and yield.
S17O08
How many seeds are acceptable in commercial citrus varieties derived from irradiation?
Williams T.E.
University of California Riverside (UCR), Botany and Plant Sciences, United States. timwill@ucr.edu
Mutation breeding, specifically through the use of irradiation directed at reducing seed numbers in normally
high-seeded varieties, has resulted in the production and release of a number of new varieties from various
citrus breeding programs. The goal of these breeding efforts, quite obviously, has been to achieve zero seeds
under all conditions of cross pollination in the irradiated selection. But is this necessary for commercial
success in new varieties developed from irradiation, or can low seed counts, in the 1-3 mean seed/fruit range,
fulfill commercial expectations for specific varieties?. This presentation will explore current experiences with
commercially released varieties developed using irradiation, explore the importance of seed count in relation
to other specific fruit quality characteristics and suggest some useful breeder guidelines for future selections.
XII INTERNATIONAL CITRUS CONGRESS 2012 - 307
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