ABSTRACT In tomato, foliar application of calcium-based nutrient solutions is used to complement soil fertilization. However, knowledge regarding the factors that influence the effectiveness of foliar fertilizer applications remains incomplete. The objective of this study was to evaluate the efficiency foliar fertilization with calcium for improving production and quality of hydroponic Sweet Grape tomatoes. An experiment was conducted in a commercial hydroponic system in a split-plit-plot scheme, with two calcium doses: 1,5 and 3 mmol L-1 of Ca. The solutions were sprayed on the leaves at intervals of 7 and 14 days, using commercial foliar fertilizers containing 0.3 g L-1 of calcium chloride or calcium acetate. The results indicate that the foliar application of calcium fertilizers, regardless of the amount of calcium provided in the nutrient solution and the frequency of applications, positively affects fruit production and quality. No difference was found between the effects of application of the two calcium sources, as well as the frequency of application.

RESUMO O tratamento de sementes com inoculantes a base de bactérias promotoras de crescimento de vegetal (BPCV) ou a aplicação de ácidos húmicos (AH) podem aumentar a produtividade de plantas de interesse agrícola. A hipótese deste trabalho propõe que é possível combinar o efeito de promoção do crescimento vegetal característico dos AH com a inoculação de estirpes selecionadas de BPCV no tratamento de sementes de milho com vias a obtenção de respostas superiores à aplicação isolada de ambos no desenvolvimento inicial do milho. Para atender esse propósito foi feita a aplicação isolada de AH ou a inoculação de BPCV das espirpes Burkholderia gladioli e Rhizobium cellulosilyticum, e o uso conjunto de BPCV e AH através do tratamento de sementes de milho. Ao final do experimento (45 dias após a germinação), as plantas foram avaliadas biometricamente, nutricionalmente e foi realizada a contagem de bactérias nas plantas pela técnica do Número Mais Provável. Os resultados demonstraram ser possível combinar os efeitos dos AH com a inoculação de estirpes selecionadas de BPCV com vias a obtenção de respostas superiores à aplicação isolada de ambos. Assim o uso de bioestimulantes à base de AH, em combinação com BPCV é positivo e complementar comparativamente aos insumos geralmente usados no tratamento de sementes de milho.

ABSTRACT Seed treatment with inoculants based on plant growth-promoting bacteria (PGPB) or the application of humic acids (HA) may increase the productivity of plants of agricultural interest. The hypothesis of this work is that it is possible to combine the effect of plant growth promoting characteristic of HA with the inoculation of PGPB selected strains in the treatment of maize seeds. Thus, providing superior responses than in single applications of both in the initial maize development. To meet this purpose, we conducted isolated application of HA or PGPB inoculation of Burkholderia gladioli and Rhizobium cellulosilyticum, and the combined application of PGPB and HA for treatment of maize seeds. At the end of the experiment (45 days after germination), the plants were evaluated biometrically, nutritionally and a bacteria count was performed in plants using the Most Probable Number technique. The results showed that it is possible to combine the effects of HA with the inoculation of selected strains of PGPB, obtaining superior responses to the isolated application of both. Thus, the use of HA-based bio-stimulants in combination with PGPB is positive and complementary compared to inputs generally used in the treatment of maize seeds.