Banca de DEFESA: LUCAS SILVA DA SILVEIRA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : LUCAS SILVA DA SILVEIRA
DATE: 28/08/2026
TIME: 08:45
LOCAL: online
TITLE:

Characterization of Herbicide Resistance, Fitness Cost, and Competitive Ability of Eleusine indica Biotypes

KEY WORDS:

goosegrass; chemical control; fitness cost; competition; soybean.

PAGES: 87
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Fitotecnia
SPECIALTY: Matologia
SUMMARY:

Goosegrass (Eleusine indica) is one of the major weed species in agricultural systems, with widespread distribution and an increasing occurrence of biotypes resistant to EPSPS- and ACCase-inhibiting herbicides. In addition to compromising chemical weed management, herbicide resistance may be associated with changes in weed growth, adaptation, and competitive ability. The objective of this study was to characterize the resistance of E. indica biotypes to glyphosate, clethodim, and haloxyfop, as well as to evaluate potential fitness costs and the competitive ability of resistant biotypes. Experiments were conducted with the following specific objectives: Chapter I, to characterize the response of one susceptible and four resistant biotypes to glyphosate, clethodim, and haloxyfop; Chapter II, to compare the growth, development, and seed production of the biotypes under herbicide-free conditions; and Chapter III, to evaluate the competitive ability of soybean in relation to E. indica biotypes. The results confirmed resistance to glyphosate in three biotypes, to clethodim in four biotypes, and to haloxyfop in three biotypes, demonstrating cases of cross-resistance to ACCase inhibitors and multiple resistance to ACCase- and EPSPS-inhibiting herbicides (Chapter I). In the fitness cost assessment, resistant biotypes performed similarly to the susceptible biotype for most of the traits evaluated. Although specific differences were observed among some biotypes, no consistent evidence of fitness penalties associated with herbicide resistance was found (Chapter II). In the competition experiments, soybean exhibited greater competitive ability than all the biotypes evaluated. The crop showed a similar response in the presence of susceptible and resistant biotypes, with no consistent differences among them in their ability to compete with soybean. Intraspecific competition was more detrimental to the crop, whereas interspecific competition had a greater effect on the growth of E. indica biotypes (Chapter III).

COMMITTEE MEMBERS:
Externo ao Programa - 1905333 - AROLDO FERREIRA LOPES MACHADO - UFRRJPresidente - 2466219 - CAMILA FERREIRA DE PINHO
Externo à Instituição - GUILHERME BRAGA PEREIRA BRAZ