EFFECTS OF A PROTEIN HYDROLYSATE APPLIED BY FERTIGATION ON THE EFFECTIVENESS OF CALCIUM AS A CORRECTOR OF BLOSSOM-END ROT IN TOMATO CULTIVATED UNDER SALINE CONDITIONS

The effects of the addition of Ca (100 and 200 g of gypsum per plant) to the substrate on the incidence of blossom-end rot (BER) in tomatoes cultivated by drip irrigation with water of 4.85 dS m-1 and high leve l of Mg salts (11.7 meq l-1) were studied, with and without the applic ation by fertigation of a protein hydrolysate containing 87.6 g l-1 of organic N (with 13.2% of free amino acids). The addition of gypsum re duced BER at best by 50%. The concentration of Ca in fruit and leaves usually increased with the addition of gypsum, as did the Ca/Mg ratio. A highly significant correlation between BER incidence and Ca concent ration in the distal portion of the fruit was found 10 days after anth esis, but not at full ripeness. Application of a protein hydrolysate b y fertigation improved the reduction of BER, with a total absence of a ffected fruits in the first truss of those plants with 200 g of gypsum . The addition of the hydrolysate increased the content of histidine ( 17%), proline (15%) and alanine (11%) in ripe fruit. A highly signific ant correlation was found between the incidence of BER and the joint c ontent of Ca and proline in the fruit.