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  • At sowing 12 June 2019
  • At harvest 18 July 2019




Romaine lettuce (Lactuca sativa)

Soil Type



Yield (fresh weight), dry weight, nutrient concentration in leaves

Polysulphate application significantly increases lettuce fresh and dry biomass, and increases Ca and S concentrations in the leaves.


Northern R&D Farm, Israel.


To evaluate Polysulphate as calcium source for lettuce, using a greenhouse soilless production system.


The experiment was designed in complete random blocks, with six replicates consisting of five pots each. Plants were grown under controlled greenhouse conditions in 4 L pots filled with perlite. Treatments included four rates of granular Polysulphate: 0 (control), 0.25, 0.50, and 0.75 g/L that were thoroughly mixed with the perlite before planting.

Water used for irrigation was desalinated using reverse osmosis to a level of 0.6 mEq Ca/L. Plants in all treatments were fertigated throughout the experiment with NPK 5:3:8 + MgSO4. Irrigation was scheduled three times a day for 10 minutes per irrigation (approx. 1 L/day).


  • Polysulphate application significantly increased lettuce fresh and dry biomass, adding up to 25% to the fresh weight of the plants.
  • Ca and S concentrations in the leaves were significantly higher with Polysulphate application, but no response was observed to the nutrient dose.
  • Polysulphate application can ensure enough available Ca to satisfy lettuce requirements and guarantee high produce quality.


Similar letters indicate no significant differences between treatments at p <0.05.