The effect of water stress and form of nitrogen on the incidence of blossom‐end rot in tomatoes

The effects of water stress, ammonium sulphate, sodium nitrate and ammonium nitrate on the incidence of blossom‐end rot (BER) in tomatoes was studied, using plants grown in peat modules. There was little evidence that water stress per se affected BER incidence, which was largely determined by the ammonium ion, as found in previous studies. Water stress increased ammonium and nitrate levels in both the peat modules and the leaves of the plants. This effect may account for the relation between moisture stress and BER reported by others.