INTRODUCTION REFERENCES METHODOLOGY RESULTS AND CONCLUSIONS Use of Microorganisms as Substitute for Inorganic Fertiliser on Serrano Pepper Serrano pepper production in south Tamaulipas is a great opportunity to supply the national and foreign demand during autumn - winter season. However, the growing cost of chemical fertilizers has increased the production cost of this crop, moreover the soil from south of Tamaulipas is clay with low organic matter content, Phosphorus and Zinc availability problems due to high pH (near to 8), all these factors make the crop nutrition manage difficult (Mata et al., 2010). The use of biofertilisers in crop production is an economical alternative, (Vessey, 2003) defines biofertilisers as substance that contains microorganisms, applied to seeds, plant surface, or within plant root tissues, which promote growth due to the increase of nutrient availability in the soil. Additionally, these microorganisms release amino acids, polysaccharides, nucleic acids, bioactive, sugars, as growth promoter (Higa, 2000). Dobereiner (1997) reported several microorganisms that fix Nitrogen directly from the environment and others help to solubilise Phosphorous in the soil in crops such as corn, rice, wheat and sugar cane. Positive effects on yield and quality have been found on pepper (García et al., 2010), maize (Villalobos et al., 2010) and sorghum production (Elizondo et al., 2010). The present research was established in order to evaluate the effect of biofertilisers on Serrano pepper yields. The experiment was developed during autumn to winter season at Research Centre ‘‘Las Huastecas’’, INIFAP-Tamaulipas, which its soil is basically clay with low organic matter content and warm sub-humid climate with rainy summers. Serrano pepper was evaluated its response to different microorganism inoculations, applying 500 g ha -1 (Figure 1). During this evaluation, six treatments, including the control, which consist of T 1 Control, T 2 Azospirillum, T 3 Pseudomonas, T 4 Mycorrhizae, T 5 Mycorrhizae + Azospirillum and T 6 Mycorrhizae + Pseudomonas, were assessed plus partial inorganic fertilisation of 50 and 75 per cent. The inoculation of microorganisms were during transplant and the yield collected data were analysed with ANOVA procedure and Duncan (p≤ 0.05), using Statistical Analysis System (SAS, 2007). J Patishtán *, H Mata **, M Ramírez *** * Campo Experimental Las Huastecas - Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias, Villa Cuauhtémoc, Tamaulipas. ** Campo Experimental Las Huastecas - Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias, Villa Cuauhtémoc, Tamaulipas. *** Campo Experimental Las Huastecas - Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias, Villa Cuauhtémoc, Tamaulipas. The figure 2, assessing two levels of inorganic fertilization, shows that there are different yield responses to biofertiliser inoculations in Serrano pepper (p≤ 0.05). Applying between 50 to 75 per cent of the total dose inorganic fertilization, under fertigation management, is possible to achieve up to 50 t ha -1, including the control treatment. In each inorganic fertilization dose level, the greatest amount of pepper production was achieved in treatments 2 and 4, obtaining close to 70 t ha -1. Daly, M. &Stewart, D. (1999). Influence of ''Effective microorganisms'' (EM) on vegetative production and carbon mineralization - a preliminary investigation. J. Sustain Agric 14: Dobereiner, J. (1997). Biological nitrogen fixation in the tropics: social and economics contributions. Soil Biol Biochem 27: Elizondo, B. J., Maldonado, M. N., C.J.L., B., Lara, G. G. J. &Garcia, D. G. J. (2010). CEPAS NATIVAS DE MICORRIZAS ARBUSCULARES PARA EL CULTIVO DE SORGO DE TAMAULIPAS. Rio Bravo, Tamaulipas: Centro de Investigaciones Regional Noreste, INIFAP. García, S. J. A., Nav, P. R. J., Zapata, B. G. J. &Sánchez, B. M. A. (2010). LA NUTRICIÓN ORGÁNICA COMO ALTERNATIVA TECNOLÓGICA PARA EL CULTIVO DEL CHILE JALAPEÑO EN QUINTANA ROO. San Francisco de Campeche: Campo Experimental Chetumal-CIRSE. Higa, T. (2000). What is EM technology? EM World J 1: 1-6. Lee, K. (1994).Effect of organic amendmentsand EM on the growth and yield of crops and soil properties. In In: Proceedings of the 2nd International Conference on Kyusei Nature Farming USDA, (Eds J. Parr, S. Homick and M. Simpson). Washington, DC. Mata, V. H., Vázquez, G. E., Ramírez, M. M. &Patishtan, P. J. (2010). Libro Tecnico: Fertirrigación de Chile Serrano con Riego por Goteo en el Sur de Tamaulipas. INIFAP. Naseem, F. (2000). Effect of organic amendments and effective microorganisms on vegetable production and soil characteristics. Park J Biol Sci 3: SAS, S. A. S. (2007). SAS for Windows ver Cary, N.C: SAS Institute, Inc. Vessey, J. (2003). Plant growth-promoting rhizobacteria as biofertilizers. Plant Soil 255: Villalobos, G. A., Medina, M. J. &López, H. M. B. (2010). EVALUACIÓN DE BIOFERTILIZANTES (MICORRIZA Y AZOSPIRILLUM) EN EL CULTIVO DE MAÍZ DE TEMPORAL EN EL ESTADO DE CAMPECHE San Francisco de Campeche: INIFAP. Xu, H. L. (2000). Effects of a microbial inoculant and organic fertilizers on the growth, photosynthesis and yield of sweet corn. Journal Crop Production(3): Figure 2. Serrano pepper yields with 75 per cent (a) and 50 per cent (b) of inorganic fertilisation plus inoculation of microorganisms previous the transplant. The biofertilisers in crop production, as reported by researches, basically increase yield. Different effects of biofertiliser have been documented in cereal crops and other vegetables such as onion, radish, cabbage and lettuce, combined with partial NPK fertiliser (Daly and Stewart, 1999; Lee, 1994; Naseem, 2000; Xu, 2000). Over all, Azospirillum, Mycorrhizae, Pseudomonas benefit on Serrano pepper growth, due to their low costs and can be applied as a substitute of inorganic fertilisers. Figure 1. Inoculation process of dissolved microorganisms in water previous to Serrano pepper transplant.