Joint International Conference on Long-term Experiments ...

The total content of soluble salts has to be adjusted and a correct system of soil fertilization
has to be established, for the greenhouse soil to correspond from the agrochemical point of
view (Neaţă Gabriela, 2002).
As regards the salinity tolerance it is well known that tomatoes do not support
concentrations over 0.17% in light soils, over 0.20% in medium soils and over 0.25% in
compact soils (Maria Apahideanu, 1998).
The salinity tolerance of the main greenhouse cultures is appreciated on the limits of the
concentrations (table 1):
Culture
Table 1 Salinity tolerance of the main greenhouse cultures
(mineral residue, g/100g sol) (after Bernstein, 1987 cited by Rusu, 1993)
The limit where the culture starts to
be affected
Fine
texture
Thick
texture
Middle
texture
The limit where the production
decreases with 50 %
Thick
texture
Middle
texture
Fine
texture
1. Cucumbers 0,15 0,20 0,23 0,25 0,30 0,35
2. Green
peppers
0,15 0,18 0,20 0,23 0,30 0,43
3. Lettuce 0,15 0,18 0,20 0,23 0,30 0,43
4. Cabbage 0,25 0,20 0,23 0,26 0,40 0,55
5. Tomatoes 0,27 0,20 0,25 0,30 0,45 0,60
6. Spinach 0,20 0,25 0,30 0,30 0,45 0,60
The prevention of the exaggerated increase of the salts content is solved by taking some
preventive and curative measures:
� Applying fertilizers in best economic doses, especially those with azoth;
� Using some fertilizers with well balanced relations between the nutritive elements
depending on the requests of the species with the needed reports;
� Application of extra-radicular fertilization during the vegetation period as a measure of
diminishing the dose applied on the soil;
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