The objective of this study was to evaluate the use of biofertilizers and saline waters on gas exchange and growth of medicinal plant Plectrantus amboinicus. The experiment was conducted in the period February to May 2013 in a greenhouse. The experimental design was completely randomized in a 2 × 4 factorial arrangement, with two levels of salinity of irrigation water (ECw: 0.7 and 3.1 dS m −1 ) and four levels of bovine liquid biofertilizer applied to the soil, corresponding to 0%, 10%, 20% and 30% of the soil volume, with five replications. The experiment lasted 60 days, counted from the beginning of the treatments. The stomatal conductance (gs), photosynthesis (A), transpiration (E), intrinsic water use efficiency (WUEi) were performed at the end of the experiment, and the height, number of leaves and stem diameter at the beginning and at the end. Generally plants subjected to salinity of irrigation water of 3.1 dS m −1 had the lowest values of gas exchange. Moreover, the application of biofertilizers and the interaction between this and salinity did not affect any growth variable studied except the stem length in the final phase which was influenced by salinity at 5% probability by F test. The average values of this variable were 57.22 cm and 69.65 cm when applied water ECw: 0.7 to 3.1 dS m −1 , respectively. The application of biofertilizers can reduce the effect of salinity on the final plant height of Plectrantus amboinicus, especially when the plants were fertilized with a dose of 20% of biofertilizers.

Resumo: Os efeitos que a salinidade do solo e da água provocam nas culturas podem ser superados utilizandose biofertilizantes. Assim, objetivou-se com o presente estudo avaliar o efeito da salinidade e do biofertilizante bovino no crescimento, na produção de óleos essenciais e nos teores de carboidratos e cloreto de plantas de malvariço (Plectranthus amboinicus). O experimento foi conduzido em casa de vegetação no período de março a maio de 2013, em vasos plásticos com capacidade de 7,5 L. O delineamento experimental utilizado foi inteiramente casualizado, em um arranjo fatorial 2 x 4, sendo dois níveis de salinidade da água de irrigação (S1=0,7 e S2=3,1 dS m -1 ) e quatro níveis de biofertilizante bovino líquido aplicados ao solo, correspondendo a B1=0, B2=10, B3=20 e B4=30% do volume do solo, com cinco repetições. Foram avaliadas: massa seca da raiz, do caule e das folhas, teores foliares de carboidrato, de cloreto e de óleos essenciais. A salinidade reduziu a biomassa seca das raízes. Porém, a aplicação de biofertilizante e a interação entre os fatores não influenciaram as variáveis biométricas, os teores de carboidratos e os de cloreto. Em todas as condições avaliadas, o óleo essencial de Plectranthus amboinicus apresentou ésteres, álcoois, fenóis, cetonas e terpenóides. Palavras-chave: Plectranthus amboinicus. Bioquímica. Adubação orgânica. Abstract:The effects of salinity of the soil and water on crops can be overcome with the use of biofertilisers. The aim of this study therefore, was to evaluate the effect of salinity and bovine biofertiliser on growth, the production of essential oils, and the carbohydrate and chloride levels in plants of Plectranthus amboinicus, known locally as malvariço. The experiment was carried out in a greenhouse from March to May 2013, in plastic pots with a capacity of 7.5 L. The experimental design utilized was fully randomized in a factorial arrangement 2 x 4, with two levels of water salinity (S1= 0.7 and S2=3.1 dS m -1) and four levels of liquid bovine biofertilizer applied to the soil, corresponding to (B1=0, B2=10, B3=20 and B4=30%) the volume of the soil, with five replications. The following variables were evaluated: root, stem and leaf dry weight, and foliar levels of carbohydrates, chlorides and essential oils. Salinity reduced the dry biomass of the roots; however, the application of biofertiliser, and the interaction between factors did not influence biometric variables, or the levels of carbohydrates or chlorides. Under all the conditions being evaluated, the essential oil of Plectranthus amboinicus showed esters, alcohols, phenols, ketones and terpenoids.