Effects of Ca Sprays on Fruit Ca Content and Yield of Tomato Variety Susceptible to Blossom-End Rot

Several factors are involved in the incidence of blossom-end rot (BER) in tomato fruit, but the main one is insufficient Ca uptake and transport through the plant, resulting in Ca deficiency in the fruit. Sprays of Ca-containing products are considered to be a possible measure to overcome the local Ca deficiency in tomato fruit. Therefore, the main objective was to evaluate the effectiveness of additional Ca supply to tomato fruits for increasing Ca content and reducing fruit damage. Sprays of five different commercial preparations containing (Brexil Duo, Calmax Zero N, Ca(NO(3))(2), CaCl(2)) or promoting (Greenstim) Ca uptake were tested using BER-sensitive large-fruit variety ‘Beorange’. The experiment was conducted in the commercial greenhouse ‘Getlini EKO’, Latvia, during the autumn–spring season of 2020/2021 under controlled conditions, eliminating the adverse impact of external factors. The results revealed that none of the preparations were effective in increasing Ca content, preventing BER, and did not promote the tomato yield. As good agricultural practices were followed in the greenhouse to manage BER, we concluded that a non-marketable yield of around 15% should be expected for ‘Beorange’ when grown under artificial light, possibly due to the impact of abiotic stresses and genetically determined susceptibility.