<p>The present study aimed to evaluate the effects of <i>Rhodopseudomonas palustris</i> on plant carbohydrate concentration and fruit production of ‘Keitt’ mangoes grown under semi-arid environmental conditions. The experiment was carried out simultaneously in two orchards with the same mango cultivar and crop management practices under semi-arid conditions in Petrolina, Pernambuco, Brazil. The study followed a randomized blocks design with treatments distributed in a factorial arrangement (7 × 8), referring to different use strategies of <i>R. palustris</i>: T1) control treatment; T2) 1.43 × 10⁷ CFU/plant via fertigation (colony forming unit); T3) 2.85 × 10⁷ CFU/plant via fertigation; T4) 4.27 × 10⁷ CFU/plant via fertigation; T5) 5.70 × 10⁷ CFU/plant via fertigation; T6) 1.43 × 10⁷ CFU/plant via fertigation + 1.43 × 10⁷ CFU/plant via leaf spray; T7) 2.85 × 10⁷ CFU/plant via fertigation + 1.43 × 10⁷ CFU/plant via leaf spray; and evaluation days after the first treatment at 0, 30, 60, 90, 120, 150, 180 and 210 days. Each treatment was composed by four replications and each replication by three plants. The use of <i>R. palustris</i> increased the total soluble carbohydrates, such as sucrose, in leaves and branches, as well as starch concentration in branches. The application of 11.43 × 10⁷ CFU/plant via fertigation + 1.43 × 10⁷ CFU/plant via leaf spray (T6) increased the production of ‘Keitt’ mangoes with caliber between 6 and 8, recommended for the European market.</p>