The effect of some salts on head weight and tipburn of lettuce and on fruit production and blossom-end rot of tomatoes.

  • C. Sonneveld
  • J. Van den Ende


In an experiment with tomatoes and lettuce grown in containers, various salts were added to the irrigation water, binary salts to give 121/2 and 25 mmol, and tertiary salts to give 81/3 and 162/3 mmol per litre water. The tomato yield was reduced by 16% at the low salt level and by 28% at the high salt level, the lettuce yield by 11 and 26%, respectively. No significant differences were found in tomato yields as a result of the various salts. Sodium bicarbonate gave a greater yield reduction in lettuce than the other salts. Calcium chloride reduced tipburn in lettuce but most other salts, in particular sodium bicarbonate, increased the disorder. Some blossom-end rot occurred in tomatoes as a result of the salt applications. Magnesium chloride resulted in more blossom-end rot than the other salts. The soil was analysed at regular intervals by means of the saturation extract. Low calcium and magnesium figures were obtained after the application of sodium bicarbonate. The uptake of nutrients in the different treatments were determined by the analysis of leaf and fruit samples. The application of the different salts was clearly reflected in the chemical composition of the crop. ADDITIONAL ABSTRACT: In a trial with container-grown tomatoes and lettuce various salts were added to the irrigation water. These comprised NaCl, KCl, CaCl2, MgCl2, NaNO3, NaCl, Na2SO4 and NaHCO3. Binary salts were applied at 121/2 or 25 mmol and tertiary salts at 81/3 or 162/3 mmol/l water. Tomato yields were reduced by 16% at the low salt level and by 28% at the high salt level, compared with normally irrigated controls. The corresponding reductions in lettuce yields were 11 and 26%, respectively. Tomatoes showed no differences in yield in response to the various salts, but with lettuce NaHCO3 reduced yield more than the other salts. Tipburn in lettuce was reduced by adding CaCl2 but increased by most other salts, particularly NaHCO3. Treatments, particularly with MgCl2, induced some blossom-end rot in tomatoes. Nutrient uptake was determined by leaf and fruit analyses. (Abstract retrieved from CAB Abstracts by CABI’s permission)