Tolerance to Lime - Induced Chlorosis and Drought in Grapevine Rootstocks - Abiotic Stress: Plant Responses and Applications in Agriculture - page 285

of iron in soil and leaves (Bavaresco et al., 1992) while in other its symptoms may be observed
at very high levels of iron in leaves (Mengel et al., 1984b). Iron also plays an important role in
activities of the enzymatic system of plants: it actively participates in photosynthetic reduction-
oxidation reactions, respiration, biosynthesis of proteins and chlorophyll, biological binding
of atmospheric oxygen, and in reduction of nitrates and nitrites (Tagliavini & Rombola, 2001).

Cultivated plants differ in their susceptibility to Fe deficiency in calcareous soil; some are not
much affected while others show severe leaf symptoms of chlorosis (Tagliavini & Rombola,
2001). In cultivars grown under conditions of a high content of carbonates in soil the content
of chlorophyll can decrease dramatically with the increasing age of plants (Shaaban et al., 2007).

The total content of lime in soil is not very useful for predicting the development of the
occurrence of this type of chlorosis. Active carbonates (active lime) is more reactive and,
therefore, able to build and maintain high levels of HCO - 3 ; for that reason it is a more reliable
indicator (Tagliavini & Rombola, 2001). In viticulture, the evaluation of conditions suitable for
the induction of chlorosis the following parameters are usually taken into account: total
carbonates (%), active lime (%) and CPI (chlorotic power index). Evaluated rootstocks are then
classified on the base of these analytic parameters. This concept resulted in the so-called
“chlorotic power index” (CPI) (Juste & Pouget, 1972. In: Huglin & Schneider, 1998). This means
that the amount of active lime is related to the amount of Fe extracted by ammonium oxalate.
Table 2 shows degrees of chlorosis intensity in relation to different values of CPI (Lupascu et
al., 2009).

CPI value Intensity of chlorosis

0 None

≤ 5 Small

6 - 15 Medium

16 -35 High

≥ 36 Very high

Table 2. Degrees of chlorosis intensity in relation to different values of CPI (LUPASCU et al., 2009).

The content of active lime in soil is a parameter, which is frequently used when selecting
rootstocks for cultivation of grapevine plants in calcareous soils (Champagnol, 1984).

The susceptibility to chlorosis is the most important selection criterion for rootstocks in many
European wine-growing regions where such a condition is prevalent due to occurrence of
highly calcareous soils.

Two basic strategies how to classify grapevine plants according to their capability to adapt
themselves to conditions, under which the lime-induced chlorosis can occur (Bavaresco, 1990):

• Strategy I involves four types of response in the roots as follows: a) enhancement of H-ions
release, b) formation of rhizodermal or hypodermal transfer cells, c) enhancement of ferric