BLOSSOM-END ROT IN TOMATOES

Blossom‐end rot (BER) of tomatoes has been studied in a glasshouse using varieties both prone and resistant to the disorder. The plants were grown in modules of peat with different amendments of lime and fertiliser and in a commercial peat mix containing magnesium ammonium phosphate as a slow release fertiliser (‘Enmag’). Nutrient solutions containing nitrogen as the ammonium ion, the nitrate ion, urea or ammonium nitrate were added daily. The incidence of BER was high with the ammonium nitrogen and was aggravated by ‘Enmag ’With nitrate nitrogen, incidence of BER was much reduced or negligible, whereas with urea or ammonium nitrate, the incidence was intermediate. Higher levels of calcium reduced the disorder. Chemical analyses of the blossom‐end of affected and healthy tomatoes showed that in BER tissues both calcium and iron were reduced whereas the potassium and phosphorus contents and the potassium‐malate ratios were increased. Copyright © 1979 John Wiley & Sons, Ltd