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The identification of natural bioactive sources capable of enhancing yield gains on agriculture is a tool to promote sustainability. In this study, the effect of foliar applications of sugarcane molasses fermented by the bacteria Corynebacterium glutamicum, containing 30% (w/v) of the amino acid L-glutamic acid was tested on organically grown potato for two seasons. Four foliar applications at intervals of ten days were made using solutions with different concentrations of the fermented broth (0.2, 0.4, 0.6, 0.8 mL L-1). Total and commercial potato yield and biochemical alterations on leaves at 50 and 60 days after planting were determined. The applications of the fermented broth promoted yield gains and changes in chlorophylls, carotenoids, nitrate reductase enzyme (EC 1.6.6.1) activity, delaying the senescence and improving the free amino acid and soluble protein content of leaves. It was concluded that the fermented broth was able of improving potato yield by stimulating the nitrate reductase activity.

A utilização de produtos biofertilizantes, como fermentados bacterianos, contendo aminoácidos, é pouco estudada na produção de mudas de hortaliças, especialmente no sistema orgânico. Neste trabalho, o objetivo foi avaliar o efeito da aplicação foliar de um fermentado bacteriano do melaço da cana, contendo 30% do aminoácido ácido Lglutâmico, no desenvolvimento de mudas de repolho. Os tratamentos, constituídos por quatro repetições, eram compostos por concentrações do fermentado (0; 0,1; 0,2; 0,4 e 0,8 mL L -1 ) aplicadas nas folhas, em intervalos de sete ou de 14 dias. Aos 35 dias após a semeadura, foram determinados o índice relativo de clorofila, a área foliar e o volume do sistema radicular. O fermentado bacteriano promoveu incrementos do índice relativo de clorofila, da área foliar e do volume radicular, quando aplicado com intervalos de 14 dias, e incremento do volume radicular, quando aplicado com intervalos de sete dias. Ocorreu redução da área foliar, quando aplicado em concentrações superiores a 0,2 ml L -1 , com intervalos de sete dias. O biofertilizante incrementa o desenvolvimento de mudas de repolho. Palavras-chave:Brassica oleracea var. capitata L., aminoácido, produção orgânica, ácido L-glutâmico, clorofila. Cinthia Biofertilizers in cabbage seedling productionThe use of biofertilizers such as bacterial fermentation broth containing amino acids is poorly studied in the production of organic seedlings. The aim of this study was to test the effect of foliar spraying of the sugarcane fermented broth containing 30% of L-glutamic acid, on the growth of cabbage seedlings, without using synthetic fertilizers. The treatments consisted of foliar spraying with solutions containing different concentrations of fermented broth (0, 0.1, 0.2, 0.4 and 0.8 mL L -1 ), in four repetitions, in intervals of seven or fourteen days. At 35 days after sowing, the following variables were determined: chlorophyll relative index, leaf area and root volume. The fermented broth increased the chlorophyll relative index, leaf area and root volume when applied in intervals of fourteen days, and increased the root volume when applied in intervals of seven days. There was a reduction in leaf area when applied in concentrations higher than 0.2 ml L -1 in intervals of seven days. The biofertilizer enhanced the development of cabbage seedlings.

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