Banca de QUALIFICAÇÃO: ELDERSON PEREIRA DA SILVA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : ELDERSON PEREIRA DA SILVA
DATE: 21/10/2025
TIME: 09:00
LOCAL: Online ( meet.google.com/xyv-yyak-upi )
TITLE:

CONTRIBUTION OF BIOLOGICAL NITROGEN FIXATION IN SOYBEAN CULTIVATION IN HIGH-YIELD AREAS OF THE CERRADO OF GOIÁS (GO) AND CAMPOS DOS GOYTACAZES (RJ)

KEY WORDS:

Glycine max L., Nitrogen balance, BNF, Sustainability.

PAGES: 17
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Fitotecnia
SUMMARY:

Soybean is the main grain crop in Brazil, standing out both in cultivated area and production. Despite the relatively modest annual growth in planted area (about 2.8%), productivity gains can still be maximized. In regions with high yields (>4,200 kg ha⁻¹), production can exceed twice the national average (3,533 kg ha⁻¹), indicating that the crop’s productive potential has not yet been fully explored. In regions where cultivation is not yet consolidated, it is necessary to investigate the contribution of biological nitrogen fixation (BNF) to the crop and the production system as a whole. In this context, research continues to be conducted not only to increase productivity but also to ensure the sustainability of the production system, with emphasis on maintaining or enhancing BNF. Thus, the objective of this study was to quantify the contribution of BNF under field conditions using the natural abundance of ¹⁵N technique. Five high-yielding soybean cultivars were evaluated in a Red Oxisol in the Cerrado region of Rio Verde (GO) and four cultivars in a Inceptisol in Campos dos Goytacazes (RJ) during the 2022/23 growing season. In the 2023/24 season, five additional cultivars were evaluated in Campos dos Goytacazes (RJ). In each experimental area, sampling was carried out in four quadrants representing the replicates. The variables analyzed included dry mass, grain yield, harvest index (HI), nitrogen harvest index (NHI), BNF contribution, and the nitrogen balance in the soil–plant system. The BNF contribution to the crop was high, showing little variation among the evaluated regions, remaining close to 80%. This regional difference was also reflected in the nitrogen balances, which were positive across all sites and growing seasons. In Rio Verde, the balances ranged from 21.18 to 36.83 kg ha⁻¹ of N, while in Campos dos Goytacazes they ranged from 13.62 to 34.58 kg ha⁻¹ in the 2022/23 season and from 11.97 to 33.84 kg ha⁻¹ in the 2023/24 season, with emphasis on the cultivars Aporé and DM 73i75 in Rio Verde and AS 3707 and BRS 1010IPRO in Campos dos Goytacazes. These results reinforce the central role of BNF as the main N source for soybean, ensuring positive nitrogen balances in the soil–plant system and highlighting its potential to sustain high yields (>4,200 kg ha⁻¹).

COMMITTEE MEMBERS:
Presidente - ***.898.198-** - SEGUNDO SACRAMENTO URQUIAGA CABALLERO - EMBRAPA
Interna - 1412091 - ERICA SOUTO ABREU LIMA
Interno - ***.864.458-** - JOSÉ IVO BALDANI - UFRRJ
Externo ao Programa - ***.588.726-** - JOSIMAR NOGUEIRA BATISTA - UFRRJ