LIBRO-CONGRESO-CITRUS

strongly decreased with the application of 30 mM NaCl. The potassium and calcium applications did not
lead to increase photosynthesis rates. Neither the Ca nor the K treatment reduced the high Cl levels found
in leaves, and leaf Na was only reduced by the CaR treatment. The calcium levels in leaves following the CaR
treatment were higher than in C plants, whereas the CaL, KR and KL treatments led to lower Ca levels than
in C plants. This was also the case with membrane stability, which increased with CaR but not with the foliar
application of Ca or either of the K treatments. Cellular damage produced by salinity decreased with KL and
both Ca treatments. These results suggest that, in general, the adverse effects of salinity on the nutritional
and physiological response of C. macrophylla are not alleviated by the foliar treatments of Ca and K applied
in this experiment.
S10P06
Effect of mulching and drip irrigation on Satsuma mandarin fruit quality in a volcanic ash soil
Han S.G., Kim Y.H., Moon Y.E., and Kang S.B.
Citrus Research Station, National Institute of Horticultural & Herbal Science, Rural Development administration, Korea.
skhan@korea.kr
The study aimed at improving water management in Satsuma mandarin (Citrus unshiu Cv. Okitsu Wase)
cultivated with macro-porous film (MPF) mulching system in an open field environment under high
precipitation regime. In those humid conditions, fruit often struggle to reach the desired total soluble
solids (TSS). The MPF mulching systems was treated to repel water when it rains and water vapor releases
from the soil. The mulching system was set up every early June before the onset of the rainy season
and lasted up to the harvest period (November) from 2009 to 2011. Some observations indicated that
TSS concentration increases from September to November, with the highest increasing rate observed in
October. On the other hand, fruit titratable acidity (TA) decreased largely in September and October, with
hardly decrease after November. Results show that fruit from trees cultivated under dry soil conditions
had higher TSS and TA. In order to identify the optimal water supply after mulching, Satsuma mandarins
were subjected to different watering treatments i) 0 (no irrigation), ii) irrigation application of 1.500 m 3 /
ha, and iii) watering at 2.400 m 3 /ha. Irrigation started when fruit reached TSS 8.0 °Brix, and lasted until
harvest. The control (no irrigation treatment) showed the highest TSS and also TA with 1.0% higher than
the high quality standard (HQS; TSS≥12°Brix, TA≤1.0%). The 2.400 m 3 /ha treatment lead to fruit with TSS
values lower than the HQS of 12.0 °Brix. The 1.500 m 3 /ha treatment showed higher TSS than 12.0 °Brix and
TA lower than 1.0%. In summary, the high quality Satsuma mandarin could be produced by drip-irrigation
with water supply at 1.500 m 3 /ha.
S10P07
Tree-to-tree variation in plant-based measurements as indicators of orange water status
Motisi A. 1 , Continella A. 2 , Massenti R. 1 , and Romolo F. 1
1 University of Palermo (DEMETRA), Italy; and 2 University of Catania (DISPA), Department of Agriculture and Food Science, Italy.
acontine@unict.it
A study was conducted in order to determine the sensitivity of measured indicators of the plant water
status in a citrus orchard. In ten adult orange [Citrus sinensis] trees, grafted on sour orange (C. aurantium)
rootstocks and drip irrigated every second day, sap flow by Granier TDP probes, leaf and xylem water
potential, gas exchange and leaf and canopy thermal imaging were hourly monitored all over the day.
The evaluations were performed during two separate clear-sky days with different environmental
conditions, respectively in the summer and autumn seasons. Variations of environmental components
(reference evapotranspiration, solar radiation, vapour pressure deficit and temperature) were recorded.
Each measurement technique resulted effective to perceive continuous plant water status at the proper
scale (tree and orchard level). In particular, transpiration rate, water deficit stress indicators, stomatal
conductance and closure were related to diurnal changes in ET0 and net radiation. Tree-to-tree variations
in the diurnal dynamics of tree gas exchange were evaluated to develop up-scaling rules of tree-level water
consumption measurements.
XII INTERNATIONAL CITRUS CONGRESS 2012 - 163
S10