BLOSSOM-END ROT CONTROL IN TOMATO (Solanum lycopersicum L.) FRUIT USING PLANT GROWTH REGULATORS | BLOSSOM-END ROT CONTROL IN TOMATO (Solanum lycopersicum L.) FRUIT USING PLANT GROWTH REGULATORS

إنجليزي. The tomato (Solanum lycopersicum L.) is the second most produced vegetable worldwide. Mexico ranks eighth as a producer and is the main exporter. This crop adapts to diverse climates and soil types, although it is susceptible to diseases and physiological disorders. Blossom-end rot (BER) is the most relevant, with damage that can reach up to 50 % of greenhouse production. This study aimed to evaluate the effect of foliar application of abscisic acid (ABA) combined with 24-epibrassinolide (EBL) to assess BER of tomato fruit in plants fed with low calcium (Ca) concentration (45 mg L-1) in the supplied nutrient solution. Likewise, the physiological and metabolic changes that these growth regulators generate in planta were determined. A 4 × 4 factorial experiment was established in a completely randomized design. Four concentrations of ABA (0, 60, 100, and 140 mg L⁻¹) and four of EBL (0, 0.0024, 0.0048, and 0.0096 mg L⁻¹) were evaluated as factors, with four replications. The percentage of BER and fruit set, photosynthesis, stomatal conductance, intercellular CO₂, transpiration, Ca concentration in leaves and fruits, and the concentration of amino acids and proteins were determined. In the first evaluation (20 d of treatment), treatments ABA3EBL2 and ABA3EBL0 showed a lower incidence of BER (80 and 66 %). In the second evaluation, EBL decreased transpiration by 50.6 %. ABA1EBL1 (35.7 %) and ABA3EBL0 (30.5 %) increased fruit Ca, while ABA2EBL1 increased leaf Ca by 62.2 %. ABA0EBL1, ABA1EBL1, ABA3EBL0, and ABA1EBL3 increased total amino acids more than twofold, and ABA2EBL2 increased protein by up to 13.6 %. These results indicate that the early application of ABA and EBL reduces BER and improves physiological and metabolic parameters in tomato plants.

الأسبانية؛ قشتالية. The tomato (Solanum lycopersicum L.) is the second most produced vegetable worldwide. Mexico ranks eighth as a producer and is the main exporter. This crop adapts to diverse climates and soil types, although it is susceptible to diseases and physiological disorders. Blossom-end rot (BER) is the most relevant, with damage that can reach up to 50 % of greenhouse production. This study aimed to evaluate the effect of foliar application of abscisic acid (ABA) combined with 24-epibrassinolide (EBL) to assess BER of tomato fruit in plants fed with low calcium (Ca) concentration (45 mg L-1) in the supplied nutrient solution. Likewise, the physiological and metabolic changes that these growth regulators generate in planta were determined. A 4 × 4 factorial experiment was established in a completely randomized design. Four concentrations of ABA (0, 60, 100, and 140 mg L⁻¹) and four of EBL (0, 0.0024, 0.0048, and 0.0096 mg L⁻¹) were evaluated as factors, with four replications. The percentage of BER and fruit set, photosynthesis, stomatal conductance, intercellular CO₂, transpiration, Ca concentration in leaves and fruits, and the concentration of amino acids and proteins were determined. In the first evaluation (20 d of treatment), treatments ABA3EBL2 and ABA3EBL0 showed a lower incidence of BER (80 and 66 %). In the second evaluation, EBL decreased transpiration by 50.6 %. ABA1EBL1 (35.7 %) and ABA3EBL0 (30.5 %) increased fruit Ca, while ABA2EBL1 increased leaf Ca by 62.2 %. ABA0EBL1, ABA1EBL1, ABA3EBL0, and ABA1EBL3 increased total amino acids more than twofold, and ABA2EBL2 increased protein by up to 13.6 %. These results indicate that the early application of ABA and EBL reduces BER and improves physiological and metabolic parameters in tomato plants.