LIBRO-CONGRESO-CITRUS

a continuous flow-through system (20°C for 3 d). The CO 2 treatment resulted in significantly higher incidence
compared to the rest. Following on from these results, postharvest ethephon (2-chloroethyl phosphoric
acid) (200 mg/L and 400mg/L) and AVG (aminoethoxy-vinylglycine) (400 mg/L and 800 mg/L) applications to
fruit resulted in a significant reduction in PS. In the subsequent season, the same treatments were applied
in an orchard one week before harvest and a similar reduction in PS was recorded. Ethylene production
from these fruit after harvest was measured and showed a transient spike in fruit from the Ethephon and
AVG treatments. The results collected over several seasons could indicate a protective action of ethylene in
reducing rind sensitivity to PS. It is hypothesised that if the internal ethylene synthesis is increased prior to
harvest in sensitive fruit, i.e. immature fruit, a reduction in PS can occur.
S09O11
Tahiti lime post-harvest evaluation and non-destructive assessment of essential oils by NIR
spectroscopy
Diaz-Candelas C.C. 1 , Morales-Payán J.P. 1 , and Romañach R. 2
1 Universidad de Puerto Rico, Recinto Universitario de Mayaguez (UPR-Mayaguez), Crops and Agroenvironmental Sciences, Puerto
Rico; and 2 Universidad de Puerto Rico, Recinto Universitario de Mayaguez (UPR-Mayaguez), Chemistry, Puerto Rico.
cecilia.diaz1@upr.edu
Near Infrared spectroscopy (NIRS) has been used as a non-destructive, real time analysis method to evaluate
the terpene content in the essential oils in citrus fruits. The C-H stretch bands confirmed the presence of
terpenes in Tahiti lime flavedos analyzed directly without solvent extractions. This method was utilized to
evaluate whether biorregulators affect the content of terpenes in the flavedo. A Tahiti lime orchard located at
Lajas, Puerto Rico was submitted to seven independent treatments of biorregulators to evaluate their effect
in fruit abscission, post-harvest life and terpene content. The solutions consisted of aminoethoxyvinylglycine
(AVG), a sea weed emulsion with a 0.01% kinetin content (Kn), a shark emulsion (H), a fertilizer containing
tocopherol and brassinolide (T Br), GA3, GA4&7, and a mixed solution of these GA’s. NIR spectrums were
taken within three days of harvest. Post-harvest quality trait changes were observed during eight weeks
to fruits stored at 10 ºC and 85% RH. The GA3 treatment yielded smaller fruits that took longer to change
their green color. AVG treatments yielded fruits with higher juice content followed by GA4&7 and the mixed
GA’s. AVG and Kn treated trees had less abscission and yielded the most fruits for six weeks after which Kn
continued this low abscission rate. With NIRS it was possible to differentiate between flavedo, albedo and pulp
and to correlate intense peaks of the flavedo spectra with three terpenes. Results strongly suggest a directly
proportional relation between terpene content and fruit maturity. A calibration model is in development.
S09O12
Postharvest blue light treatments affect citrus fruit susceptibility to disease by altering oxylipin
biosynthesis
Alférez F. 1 , Liao H.L. 2 , and Burns J.K. 2
1 Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Laboratorio de Fisiología Y Biotecnología Postcosecha, Spain; 2 Citrus
Research and Education Center-University of Florida (CREC-UF), Horticultural Sciences, USA. alferez@iata.csic.es
The effect of blue light on infection by different postharvest pathogens was investigated in tangerines and
sweet oranges during postharvest. Exposure of fruit to 410-540 nm blue light at a fluency of 40 μmol m-2s-1
reduced symptom development of Blue Mold (Penicillium italicum), Green Mold (P. digitatum), and Stem End
Rot (Diaporthe citri) postharvest decays. However, blue light also reduced in vitro fungal growth of P. italicum
and D. citri and activity of fungal polygalacturonase. Blue light treatment induced phospholipase A2 (PLA2)
gene expression in ‘Fallglo’ tangerines. Inhibition of PLA2 activity allowed infection, whereas inhibition of
phospholipase D (PLD) expression by 580-670 nm red light was correlated with infection. These data suggested
induction by blue light of the oxylipin pathway. Gas chromatography-mass spectrometry analysis of flavedo
oil showed that blue light induced accumulation of the C8 oxylipin octanal. Application of octanal suppressed
growth of P. italicum, P. digitatum, and D. citri in vitro. Treatment of fruit with octanal suppressed symptom
development caused by Penicillium and D. citri. The effect of blue light on citrus decay could be due to its impact
on fungal growth and development, and the induction of fruit response via oxylipin synthesis in the peel.
XII INTERNATIONAL CITRUS CONGRESS 2012 - 137
S09