Effect of two irrigation rates on yield, incidence of blossom-end rot, mineral content and free amino acid levels in tomato cultivated under drip irrigation using saline water

An experiment investigated the effects of two rates of irrigation, one of w hich reflected a substantial degree of water stress, on the mineral content , free amino acid levels and incidence of blossom-end rot (BER) in tomato ( Lycopersicon esculentum Mill. 'Durinta'). The plants were grown in the open with drip irrigation using saline water from a well (mean ECW 5.2 dS m(-1) ). The yield per plant was higher and fewer fruit were affected by BER in t he treatment involving the higher level of irrigation. The fruit of the fir st and fifth truss. and the leaves immediately above, were analysed for the ir macronutrient, micronutrient and free amino acid content. The macronutri ent leaf and fruit content hardly showed any difference, only the N concent ration in fruit being significantly affected in the water stressed plants, in which the levels were higher. The Ca concentration in the stylar portion of mature fruit, which is related with the incidence of BER, was not signi ficantly affected by the level of irrigation. As regards micronutrients, on ly the Fe (in leaf and fruit of the first truss), Cu (in leaf of the first truss), Zn (in leaf and fruit of the first truss, and leaf of the fifth tru ss) and Mn (in leaf of the first truss) concentrations differed significant ly, The total free amino acid leaf content was similar in both irrigation t reatments. However, the total free amino acid content of fruit, significant ly those of the first truss, was higher in the less irrigated treatment. Th e amino acids: aspartic acid (only from the first truss), glutamic acid, pr oline and alanine had high concentrations in the fruit of the less irrigate d plants, while the gamma-aminobutyric acid and phenylalanine (only from th e fifth truss) concentrations were higher in fruit of the more irrigated pl ants.