Extrato de nódulos como inoculante alternativo para fixação biológica de nitrogênio em feijão-fava

Abstract

The lima bean (Phaseolus lunatus L.) is a legume of great importance in family farming, standing out for its hardiness and nutritional value. However, the low availability of nitrogen in the soil limits its productivity, making biological nitrogen fixation (BNF) a sustainable alternative. BNF, mediated by rhizobia, reduces the need for synthetic fertilizers, but the high cost and limited accessibility of commercial inoculants make its use difficult for small farmers. In this context, inoculation with nodule extract may be a viable and efficient alternative to promote BNF, growth and crop productivity in an affordable and sustainable manner. Therefore, the objective of the present study was to evaluate the use of nodule extract as an alternative inoculant for BNF in lima bean cultivars. The experiment was conducted in a completely randomized design, arranged in a 4 x 3 factorial scheme, consisting of four N sources (control without N, nodule extract inoculant, commercial inoculant and nitrogen fertilization - 100 kg ha-1) and three lima bean cultivars (ST BRANCA, MRR MARROM and ST RAJADA). At the beginning of flowering, the following were evaluated: shoot height, shoot and root dry mass, number of nodules, number of viable nodules and nodule dry mass. The nodule extract promoted greater efficiency in nodulation, with an increase in the number of nodules compared to commercial treatments and with nitrogen fertilization, proving its efficiency in biological nitrogen fixation. An increase in shoot and root biomass was also observed in some cultivars. Among the cultivars evaluated, the Marrom and Rajada varieties were the most responsive to inoculation, standing out as potential targets for future applications of this technology