Bactérias endofíticas não homólogas associadas a doses de nitrogênio na cultura do tomateiro

Abstract

The use of inoculants composed by micro-organisms with the ability to promote growth and increase the yield in plants is an important alternative to chemical fertilizers. In this context the endophytic bacteria can act on reducing the use of fertilizers and promote plant growth. The objective of this study was to evaluate the efficiency of a mix of five isolated non-homologous endophytic bacteria and two inoculation methods on the development, growth, yield and nutrition of tomato fruit fertilized with different doses of nitrogen. The experiment was performed in a greenhouse located at State University of Montes Claros, Janaúba, MG, Brazil. The experimental design was in randomized blocks in a factorial scheme (2 x 6+3), with four replications and one plant per parcel. The treatments consisted of two inoculation methods: seed microbiolization and post-emergence inoculation; six doses of nitrogen fertilization: 0, 129, 258, 387, 516 and 645 kg ha-1; and three controls (without inoculation of the mix of bacteria): (1) absence of nitrogen fertilization and application of rock dust - Phosphate rock of sedimentary origin Itafös; (2) 100% of the nitrogen fertilization and application of rock dust; and (3) 100% of the nitrogen fertilization and application of superphosphate. Only the control number (3) did not receive the rock dust as a source of phosphorus. Climatic factors were monitored and the phenology, growth, yield and fruit nutrition were evaluated. In general, the inoculation methods did not affect the characters of growth and yield. However these same variables were strongly influenced by doses of N. The lower doses of nitrogen committed the phenological development of the crop. The average accumulation of total dry matter in the plants was distributed in 13.57% for roots, 28.55% for stems, 23.92% in leaves and 34% in the fruit. The yield of tomato increased significantly with increasing nitrogen doses. The average concentration of macro and micronutrients in tomato fruit was: K>N>P>Ca Mg>S (3.98; 1.34: 0.21; 0.17: 0.17: 0.15 dag kg-1. respectively) and Mn Cu>Fe>Zn (71.88: 56.71: 55.63 and 23.68 mg kg-1, respectively). Significant differences between the inoculation methods for contents of N, K and Ca, Zn, Fe, Mn and Cu were observed. The inoculation of bacteria along with the nitrogen fertilization increased the concentration of micro-nutrients present in fruits of tomato "Dominator FI" grown in pots. The maximum increases observed for Fe, Zn and Mn in the fruits were 186.59 and 66%, respectively.