LIBRO-CONGRESO-CITRUS

05, 2010 -1 1 and 2011-2012. In this work we describe and compare the effects of the last two frost periods
on fruit and vegetative damage in lemon trees varieties (Citrus limon) in the above mentioned area. During
the 2010-2011 campaign, frost damage was more severe than in the current year 2011-2012. Temperatures
in the citrus fields reached 6.63 °C with 10 hours of temperatures below 0 ºC. Frost-induced damage in fruits
and vegetative tissue in orange and mandarin varieties were scarce whereas they were higher in grapefruit
and severe in lemon trees, both in varieties grafted on Citrus macrophylla and on sour orange. Among lemon
varieties studied, the most sensitive to frost turned out to be ‘Messina’. The risk of frost in the citrus area of
Murcia for a critical temperature of -3 °C was also studied. The probability of frost damage is 2% on the coast
and 60% in the inland valleys of Murcia.
S08P18
Physiological investigation of tolerance to iron chlorosis of ‘Navelina’ orange budded on different
citrus rootstocks
Çimen B., Yeşiloğlu T., İncesu M. and Yılmaz B.
University of Cukurova (CU), Department of Horticulture, Turkey. bcimen@cu.edu.tr
In this study, physiological responses of ‘Navelina’ orange grafted on eight different citrus rootstocks to
iron deficiency were investigated under high pH conditions. ‘Navelina’ scion grafted on ‘Tuzcu 31-31’ sour
orange, ‘Gou Tou’ sour orange, ‘Volkameriana’, ‘Antalya Cleopatra’ mandarin, ‘Carrizo’ citrange, ‘Troyer’
citrange, ‘C-35’ citrange and Poncirus trifoliata were grown in a plant growth chamber and irrigated with
a modified Hoagland nutrient solution. In order to mimic an iron.deficient environment, 10 µM FeEDTA, 3
mM NaHCO 3 and 2g/l CaCO 3 (pH=7.8) were added to the nutrient solution. Control plants were irrigated
with a nutrient solution containing 100 µM FeEDTA (pH=6) for five months. At the end of the experiment,
iron chlorosis color scale, leaf total and active Fe concentrations, Photosystem II efficiency (Fv’/Fm’),
peroxidase and catalase activities were determined. In Fe-deprived leaves of ‘Navelina’ grafted on ‘C-
35’ citrange and Poncirus trifoliata, total and active Fe concentrations and efficiency of PSII significantly
decreased. These plants exhibited more severe Fe chlorosis symptoms than plants grafted on the rest of
rootstocks. Young ‘Navelina’ trees grafted on ‘Tuzcu 31-31’ sour orange and ‘Gou Tou’ were less affected
in terms of all parameters. As a result, ‘Navelina’ scions grafted on ‘Tuzcu 31-31’ and ‘Gou Tou’ sour
oranges were the most tolerant; the ones grafted on ‘C-35’ citrange and Poncirus trifoliata were the most
susceptible to iron deficiency.
S08P19
Differential tolerance to iron deficiency of citrus rootstocks grown in calcareous soil
İncesu M., Yeşiloğlu T., Tuzcu Ö. and Çimen B.
University of Cukurova (CU), Department of Horticulture, Turkey. meralincesu@gmail.com
In this study, seedlings of 14 citrus genotypes used as rootstocks were tested in calcareous soil conditions
(pH 7.8.) for their tolerance to lime-induced chlorosis in Adana-Turkey. The effect of iron deficiency on leaf
active and total iron, leaf chlorophyll and leaf visual chlorosis were investigated. According to results of leaf
chlorophyll and visual leaf chlorosis, ’Swingle’ citrumelo, ‘Pomeroy’ trifoliata and ‘Sarawak’ bintangor showed
severe chlorosis on their leaves but these genotypes had the highest leaf total iron concentration (Fe paradox
determined on these genotypes). At the end of the experiment, genotypes were classified in six categories:
a) very tolerant: ‘Tuzcu 31-31’ sour orange, ‘Gou Tou’ sour orange, ‘Antalya Cleopatra’ mandarin and ‘Carrizo’
citrange; b) tolerant: ‘Tuzcu 891’ sour orange, ‘Volkameriana’,’ Nasnaran’ mandarin and ‘Marumi’ kumquat;
c) moderately tolerant: hybrid of ‘Cleopatra’ mandarin and ‘Swingle’ citrumelo and ‘C-35’ citrange d)
susceptible: ‘Swingle’ citrumelo and ‘Pomeroy’ trifoliata e) moderately susceptible: ‘Sarawak’ bintangor; and
f) very susceptible: local Poncirus trifoliata.
XII INTERNATIONAL CITRUS CONGRESS 2012 - 127
S08