Effects of Environmental Factors on Seed Germination and Emergence of Glyphosate Resistant and Susceptible Sourgrass

Abstract

-Sourgrass is one of the most problematic weeds of Brazil. It is an aggressive species in the allocation of resources from the environment and reported to be glyphosate resistant in several states of the country. This work has aimed to verify environmental effects on seed germination and seedling emergence of sourgrass. Laboratory and field trials were conducted to determine the effects of temperature, light, photoperiod, water availability and depth of burial in germination and emergence of seeds. The maximum germination was greater than 80% for seed originated from resistant plants between 15 and 30 o C. For the susceptible ones, the maximum germination occurred only at 30 o C. Germination occurred for both biotypes independent of the presence of light. The best photoperiod for germination of both biotypes was between 8 and 14 hours. Seeds originated from resistant plants showed higher germination levels at low temperatures in the presence of light and in less water availability. There was no germination from -0,8 MPa for both biotypes. The emergence for both biotypes was low, indicating that seed burial could be used in the management of the species. Seeds from resistant plants showed higher and larger germination in temperatures, water content and depth of burial ranges than from originated from susceptible plants.Keywords: Digitaria insularis, water availability, photoperiod, seeds, temperature. RESUMO -O capim-amargoso é uma das espécies mais problemáticas da agricultura brasileira. É uma espécie agressiva na alocação de recursos do meio

Herbicide Resistance in Brazil: Status, Impacts, and Future Challenges

“…The species of the genus Conyza, which have a high invasive potential due to the large seed production, the rapid and high germination capacity, cause great damage to agriculture, and due to their poor interspecific differentiation, it can be an exchange of resistant alleles between species [42]. However, D. insularis has been, among glyphosate resistant species, one of the main problems to be faced; therefore, greater efforts have been made to characterize the factors involved in its resistance, dispersal and management [12,[43][44][45][46][47][48]. Molecular studies showed that the first glyphosate resistant D. insularis populations found in the country (Guairá-Paraná) came from Paraguay…”

Germinação De Sementes De Capim Amargoso (Digitaria Insularis) Na Presença De Herbicidas Residuais

“…O forte estímulo para quebra de dormência das sementes de Digitaria insularis poderia ser, ainda, intensificado pela simples deposição das sementes sobre o papel mata borrão, com grande disponibilidade de água, oxigênio e luz, sem os impedimentos representados pelo enterrio das sementes e presença de coberturas de solo (PETTER et al, 2015;MARTINS et al, 2017). Este fato poderia representar uma situação excepcionalmente favorável à germinação, uma vez que para Pereira et al (2017) a grande capacidade reprodutiva e de infestação seria inerente a espécies de grande agressividade e plasticidade ecológica como capim amargoso.…”

Efficiency of Isolated and Associated Herbicides to Control Glyphosate-Resistant Sourgrass

“…Sourgrass (Digitaria insularis) is a perennial plant belonging to the Poaceae family that, under Brazilian conditions, can emerge and develop over the year (Martins et al, 2017). After its development and formation of rhizome, the difficulty of its control increases (Gemelli et al, 2012).…”