Tolerance to Lime - Induced Chlorosis and Drought in Grapevine Rootstocks - Abiotic Stress: Plant Responses and Applications in Agriculture - page 284

A high content of lime mostly causes a low availability of iron, which is a result of its non-
solubility occurring in soils showing higher values of pH. Under such conditions, iron cannot
be uptaken by roots of plants (Hell & Stephan, 2003).
This lime-induced iron deficiency shows a strong effect not only on grapevine plants but also
on some other economically important fruit species cultivated on calcareous soils. It is quite
common also in peach, pear, quince-tree, kiwi, and citrus fruit plantations (Tagliavini &
Rombola, 2001).
Lime-induced stress conditions show a strong effect on production of grapes and reduce the
yield of grapes per vine. When growing grapevine on calcareous soils, a lower number of
grapes per annual shoot depends on stress conditions existing in the preceding growing season
(when the flower buds were differentiated) while a small size of grapes and berries is a
consequence of iron deficiency in the current year (Bavaresco, Presutto, Civardi, 2005).
Because the lime-induced chlorosis affects above all the growth of grapevine plants, influences
the total leaf area capable of photosynthetic activities and thus also yield and quality of fruit
and for that reason it is possible to say that iron deficiency is caused mainly by higher levels
of calcium carbonate and the resulting high contents of bicarbonates in soil. These high levels
of bicarbonate ion are typical just for these calcareous soils (Pestana, Faria, De Varennes,
2004; Mengel, Breininget, Bübl, 1984). Under such conditions, the occurrence of chlorosis
symptoms is quite common and for that reason this type of chlorosis may be defined as a lime-
induced iron chlorosis or, abbreviated, lime-induced chlorosis (Pestana et al ., 2004).
The identification of chlorosis symptoms in vineyards is very important because it enables to
perform protection of plants against mechanisms that induce this plant disease. The identifi‐
cation can be performed by means of leaf analysis that enables to estimate contents of indi‐
vidual macro and microelements in leaf blades and/or leaf petioles.
The leaf analysis enables to identify all factors that can influence the availability of nutrients
in soil and their uptake by plants; it also can provide information about the nutrient balance
of plants in the moment of sampling (Pestana et al., 2003).
3.2. Causes of the occurrence of lime-induced chlorosis
Although the reasons of the occurrence of this type of chlorosis seem to be relatively definite,
the mechanism of its occurrence is still not explicitly defined. It seems that different forms of
iron present in soil and their availability for plants contribute a lot to the occurrence of this
type of chlorosis. Even in very small amounts, iron represents one of those minerals, which
are utilised by plants to assure their sound growth. Iron is used by plants in two forms, viz. as
Fe 2+ and Fe 3+ .
Iron chlorosis affects susceptible plants growing on calcareous soils. Different kinds of
carbonates induce different degree of chlorosis. Chlorosis is high for magnesite, hydromag‐
nesite and calcite and low for aragonite and nil for dolomite (Fregoni, 1980). There are several
different views concerning iron concentration in soil and its relationship to the occurrence of
chlorosis. In some cases the lime-induced chlorosis can occur under conditions of a low content