In recent years, biofertilisers have emerged as a promising component of an integrated nutrient supply system in agriculture. The objective of this study was to examine the influence of selected biofertilisers on the vegetative growth, the content of N, P₂O₅ and K₂O in the leaves and stems, and on the physiological parameters of pepper of the variety of ‘Sofiiska Kapiya’ cultivated under organic agriculture conditions. This experiment was carried out from 2009 to 2011 on the experimental fields of the Agroecological Centre at the Agricultural University-Plovdiv (Bulgaria), situated on the territory of a certified ecological farm. The study included the following biofertilisers – Boneprot, Lumbrical, Baikal EM “Effective Microorganisms”, Emosan, and Bio One. The results of the biometric measurements of the average plant height at the end of the vegetative period showed the highest values for the variant treated with Emosan on the Boneprot basic fertilisation (62.60 cm – 2009; 64.80 cm – 2010, and 63.87 cm – 2011). Upon feeding with the biofertilisers Emosan and Baikal EM on basic fertilisation with Boneprot (2009, 2010 and 2011) at the pepper mass fruit yield stage, plants showed higher values of net photosynthesis (P_N) that were also similar to the high values observed in the flower bud stage. The highest intensity of transpiration (Е) was observed for the variants treated with the biofertilisers Baikal EM (2009 and 2011) and Emosan (2010) on basic fertilisation with Boneprot. It was concluded that the feeding with Emosan stimulated the vegetative growth of the pepper plants due to the high concentrations of nutrient-providing proteins contained in this biofertiliser. The results showed that biofertilisers do not significantly impact the P content of the pepper leaves and stems, but changes were more obvious in the leaves. The fertilisation with the studied biofertilisers increased the K2O content in leaves and stems compared to the control (non-fertilised) plants; the values were higher for the leaves.

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