Federal University of Roraima

About: Federal University of Roraima is a based out in . It is known for research contribution in the topics: Population & Thermogravimetry. The organization has 981 authors who have published 1218 publications receiving 7849 citations. The organization is also known as: Federal University of Roraima.

Crescimento inicial do feijão-caupi após aplicação de herbicidas em pós-emergência

Abstract: The objective of this work was to evaluate the tolerance of cowpea, BSR Arace, to different herbicides applied in the post-emergence period, in the initial phase of plant growth. The experiment was conducted in a greenhouse, in a completely randomized design, with four replications. The treatments evaluated were: haloxyfop (60 g ha -1 ), lactofen (180 g ha -1 ), chlorimuron-ethyl (17,5 g ha -1 ), bentazon (576 g ha -1 ), bentazon + imazamox (600 + 28 g ha -1 ), imazethapyr (100 g ha -1 ), fomesafen (250 g ha -1 ), quizalofop-P-ethyl (62,5 g ha -1 ), lactofen + quizalofop-P-ethyl (180 + 62,5 g ha -1 ), fomesafen + quizalofop-P-ethyl (250 + 62,5 g ha -1 ) and a control. Were realized visual evaluations of intoxication, plant height, dry leaf mass, stem, root, total dry mass and leaf area. The herbicides haloxyfop and quizalofop-P-ethyl they caused minor damage to the development of cowpea plants. The chlorimuron-ethyl caused severe damage to the crop, interrupting their growth. The lactofen + quizalofop-P-ethyl and fomesafen + quizalofop-P-ethyl mixtures caused high damage to the culture, with lactofen + quizalofop-P-ethyl causing the plants to die at 21 DAAH. It was concluded that cowpea, cv. BRS Arace, have tolerance to haloxyfop and quizalofop-P-ethyl herbicides, and moderate tolerance to imazethapyr and bentazon + imazamox. The lactofen + quizalofop-P-ethyl and fomesafen + quizalofop-P-ethyl mixtures showed a synergistic effect on bean cowpea. The lactofen + quizalofop-P-ethyl mixture and the chlorimuron-ethyl herbicide cause irreversible damage to the bean cowpea crop.

Diversity and capacity to promote maize growth of bacteria isolated from the Amazon region

Abstract: Maize plants can establish beneficial associations with plant growth-promoting bacteria. However, few studies have been conducted on the characterization and inoculation of these bacteria in the Amazon region. This study aimed to characterize endophytic bacteria isolated from maize in the Amazon region and to assess their capacity to promote plant growth. Fifty-five bacterial isolates were obtained from maize grown in two types of ecosystems, i.e., a cerrado (savanna) and a forest area. The isolates were characterized by the presence of the nifH gene, their ability to synthesize indole-3-acetic acid (IAA) and solubilize calcium phosphate (CaHPO4), and 16S rRNA partial gene sequencing. Twenty-four bacteria contained the nifH gene, of which seven were isolated from maize plants cultivated in a cerrado area and seventeen from a forest area. Fourteen samples showed the capacity to synthesize IAA and only four solubilized calcium phosphate. The following genera were found among these isolates: Pseudomonas; Acinetobacter; Enterobacter; Pantoea; Burkholderia and Bacillus. In addition, eight isolates with plant growth-promoting capacity were selected for a glasshouse experiment involving the inoculation of two maize genotypes (a hybrid and a variety) grown in pots containing soil. Inoculation promoted the development of the maize plants but no significant interaction between maize cultivar and bacterial inoculation was found. A high diversity of endophytic bacteria is present in the Amazon region and these bacteria have potential to promote the development of maize plants.

Taxonomic relevance of seed and seedling morphology in two Amazonian species of Entada (Leguminosae)

Abstract: We carried out a comparative morphological study to evaluate the taxonomic value of seed and seedling traits of Entada polystachya and E. simplicata (Leguminosae, Mimosoideae, Mimoseae). Seeds of both species were collected from wild populations in Roraima State, Brazil. Our results show consistent quantitative and qualitative differences between these species regarding their seeds and seedlings. Testa fracture lines, funiculus impression, lens characters, radicle shape and length, and cotyledon lobes length, seedling morphology group, number of pinnae at first node, and hypocotyl length permit a straightforward distinction of E. polystachya from E. simplicata, supporting a recent treatment of the latter taxon as a distinct species, endemic to Roraima State, northern Amazonia, Brazil.