LIBRO-CONGRESO-CITRUS

S06O06
Endogenous factors affecting fruit color development in navel sweet oranges
Gambetta G. 1 , Gravina A. 1 , Fasiolo C. 1 , Martínez-Fuentes A. 2 , Reig C. 2 , Mesejo C. 2 , Bentancur O. 3 , and Agustí M. 2
1 Facultad de Agronomía. Universidad de la República (UDELAR), Producción Vegetal, Uruguay; 2 Universidad Politécnica de Valencia
(UPV), Instituto Agroforestal Mediterráneo, España; and 3 Facultad de Agronomía. Universidad de la República (UDELAR), Biometría,
Estadística y Computación, Uruguay. cfasiolo@gmail.com
Fruit colour change is positively associated to endogenous abscisic acid (ABA), soluble carbohydrates (CHOs),
and negatively related to nitrogenous (N) application, but its endogenous evolution is not clear at all. The
objective of this work was to study the effect of two growth regulators on fruit colour evolution and on
the time course of endogenous ABA, CHOs and N concentration in the flavedo of ‘Navelina’, ‘Washington’
navel and ‘Navelate’ sweet oranges. Foliar sprays of GA3 (20 mg L -1 ) or norflurazone, an ABA inhibitor (NFZ,
1 mM), were applied prior to colour break, to adult plants, during two years. In the three cultivars, GA3
delayed colour break and its final intensity, while NFZ did not affect it. In control fruits, CHOs concentration
increased during colour development and N (total and proteinaceous fraction) concentration diminished.
In all experiments, GA3 reduced flavedo CHOs concentration; however, results on N concentration were
inconsistent. In ‘Navelina’ oranges, GA3 reduced ABA concentration in the flavedo along with colour delay.
However, in the other two cultivars, flavedo ABA concentration of GA3-treated trees was slightly but not
significantly lower than control fruit. NFZ did not affect ABA, CHOs or N concentration in the flavedo according
to colour evolution. Possible roles of these endogenous substances on colour development are discussed.
S06P01
Effect of continuously high temperature throughout a growth period on flowering, physiological
fruit drop and fruit quality in satsuma mandarin
Sato K.S., Fukamachi H., and Ikoma Y.
Institute of Fruit Tree Science, National Agriculture and Food Research Organization (NARO), Citrus Research Division, Japan.
satokei@affrc.go.jp
In Japan, some reports suggest that annual mean temperature in future (2081-2100) will be 2-3 °C higher
than that in recent times (1981-2000). However, in satsuma mandarin the influence of continuous high
temperature throughout a growth period was not well understood though the influence of high temperature
during short terms (i.e., physiological fruit drop, ripening) has been well studied. Thus, we investigated the
effect of continuous high temperature from pre-sprouting to fruit maturation on flowering, physiological fruit
drop and fruit quality in satsuma mandarin.
Temperature treatment for satsuma mandarin was conducted with a temperature gradient greenhouse
(TGG) in which two temperature zones were established. One zone was maintained at ambient temperature
(control). The other zone was maintained at 2°C above ambient temperature (plus 2°C treatment).
Flowering in plus 2°C treatment occurred earlier than that in control. There was little difference between
plus 2°C treatment and control in fruit set rate after physiological fruit drop although physiological fruit drop
occurred earlier in plus 2°C treatment than in control. At optimum harvesting time, color development in plus
2°C treatment was similar to that in control. However, peel puffing was enhanced in plus 2°C treatment. There
was little difference in sugar and acid content between plus 2°C treatment and control. These findings suggested
that the continuous temperature rise of 2 °C might have a bad influence on peel puffing in satsuma madanrin.
S06P02
Evaluations of potential fruit abscission and characteristics of seeded and seedless fruit
abscission in several citrus species during physiological fruit drop
Kitajima A. 1 , Li X. 2 , Habu T. 1 , Kataoka K. 1 , Nakazaki T. 1 , and Yonemori K. 1
1 Experimental Farm, Graduate School of Agriculture, Kyoto University (EFGAKU), Experimental Farm, Japan; and 2 Graduate School of
Agriculture, Kyoto University (GAKU), Plant Production Control Lab., Japan. kitajima@kais.kyoto-u.ac.jp
We developed an evaluation method for the potential fruit abscission and investigated the characteristics of
seeded and seedless fruit abscission during secondary fruit drop in several citrus species.
XII INTERNATIONAL CITRUS CONGRESS 2012 - 97
S06