ISHS Acta Horticulturae 69: II International Symposium on Pear Growing
IRON CHLOROSIS OF PEARS IN THE NURSERY |
| Authors: | I. MILJKOVIC, A. HADROVIC |
| Abstract:
Although the phenomenon of iron-chlorosis of fruittrees draws attention of many scientists over 130 years, nevertheless till now it is insufficiently investigated. On the basis of the investigations of a great number of scientists a conclusion may be drawn that iron-chlorosis is a very complex problem caused directly or indirectly by many factors. Among them especially important are: low iron supply (Oserkowsky 1933, Olsen 1935, Bennett 1945, Jacobson 1945, Brown 1955, Ivanov 1968), calcium carbonate in soil (Drouineau 1941, 1949, Barthelet and Drouineau 1943, Mc Georg 1949, Principi 1958, Wallace and Lunt 1960, Henke and Mihatsch 1963, Calabrese 1965, Miljkovic et al. 1976), bicarbonate in soil or irrigation water (Harley and Lindner 1945, Lindsey and Thorne 1954, Porter and Thorne 1955), high pH (De Kock 1955, Liwerant 1960), high phosphate (De Kock 1955), high potassium (Lindner and Harley 1944), high levels of nitrogen (Bennett 1945, Ivanov 1968), high levels of heavy metals such as manganese, copper and zinc, over-irrigation or high water conditions, low temperature, high light intensity etc. Chlorosis is prevalent on some calcareous soils, particularly when they are wet or subjected to temperature extremes. The pear is more subject to iron-chlorosis when it is lime-induced. A great number of investigations found that chlorosis appears with various quantities of total and available carbonates. So Barthelet and Drouineau (1943) found chlorosis on the soils containing more than 8% available carbonates, Depardon and Buron (cit. Coutanceau 1953) on the soil with 2% to 4.1%, Henke and Mihatsch (1963) on the soil with 3.3% to 4.1%, Miljkovic et al. with 1.5% to 3.5% etc. For a practical necessity on calcareous soils it is important to investigate the relation between pear trees and soil chemical properties. Investigations of iron-chlorosis of pear trees are particularly important in semi-arid region on calcareous soils where irrigation waters may be high in bicarbonate or where the soil is high pH. In literature we find the datas on different sensitivity of pear trees chlorosis is in relation to rootstocks. A few data are on differences in sensitivity of certain varieties. | |
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