Potential for Fourier transform infrared (FTIR) spectroscopy toward predicting antioxidant and phenolic contents in powdered plant matrices.

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.

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

The objective was to evaluate weed phytosociology and similarities between crop management systems in the Chapadões region. The experiment was conducted at in agricultural area located in the municipality of Chapadão do Sul, MS, during the 2016/17 harvest. Three crop managements strategies were used: (1) cotton/soybean/Urochloa, (2) millet/soybean/millet and (3) millet/soybean/crotalaria. A phytosociological survey of weeds was carried out during soybean cultivation and cover crops growth, in succession. The evaluation area for each management strategy was 0.5 ha. Soybean surveys were carried out in October and January, while the cover crop surveys were performed in February and May. The relative frequency (RF), relative density (RD), relative abundance (AR), and relative importance (RI) of weeds, Venn diagram, and Jaccard and Sorenson similarity indices were evaluated. The management area represented by the cotton/soybean/Urochloa rotation had fewer weed species than others. The species Cenchrus echinatus, Digitaria insularis, Digitaria sanguinalis, Eleusine indica and Commelina benghalensis had the highest phytosociological indeces among the monocotyledons. Attention is required for managing the dicotyledons Amaranthus deflexus, Conyza canadensis and Senna obtusifolia despite their low indices because of herbicide resistant cases. The highest indeces of similarity were found between managements areas 2 and 3, which did not rely on cotton cultivation prior to soybeans.

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Crop management and its effects on weed occurrences

The millet crop in recent decades has shown an increase in planted area, mainly in the Cerrado region. However, there are few studies related to the management and phytossociology of weeds in this culture. Thus, the objective of this research was to perform a phytosociological survey in millet under different soil managements in Savanna Sul-Mato-Grossense region. The experiment was conducted in the experimental area of Universidade Estadual de Mato Grosso do Sul – Unit of Aquidauana (UEMS/UUA), in Aquidauana-MS. The area is cultivated to five years with soybeans in first crop and corn in second. The experimental design was randomized complete block in a split-plot design consisting of four blocks with four replications. In the plots were used soil preparation systems (minimum tillage and no-tillage) and in the subplots was utilized the nitrogen fertilization at 50 kg ha -1 and absence of nitrogen on millet at 25 days after emergence (DAE). Were evaluated the parameters number of species (NS), total number and dry mass of weeds (TN and DMW, respectively), dry mass of millet (DMM) and frequency (F), density (D), abundance (A) and Importance Value (IV) of weeds. The no-tillage system provided greater dry mass of weeds, whereas the nitrogen resulted in a smaller total number of weeds (TN). Cynodon dactylon and Commelina benghalensis were the most predominant species on area.

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Phytosociology of weeds in millet under different soil managements in savanna sul-mato-grossense = Fitossociologia de plantas daninhas em milheto sob diferentes manejos do solo no cerrado sul-mato-grossense

Among the several factors that negatively influence cowpea culture, weeds have been responsible for the reduction of growth, development and productive performance of the crop, making it necessary to establish management strategies based on phytosociological studies of weed species in growing areas. Therefore, the objective of this research was to evaluate the floristic composition of weeds, aiming to identify the main species and their dynamics, and to consider their distribution in time and space as pertaining to the cultivation of a modern variety of cowpea, cv. BRS Novaera, in dystrophic Red-Yellow Argisol, in the Midnorth region of the state of Piauí, Brazil. The phytosociological survey of weeds was carried out in three sessions: the first one was immediately before the area was desiccated with glyphosate (15 days before sowing the cowpea), and the others were at 20 and 40 days after sowing (DAS). Following the quantification of species and number of individuals, the following phytosociological parameters were calculated: frequency and relative frequency; density and relative density; abundance and relative abundance; and importance value index. It was concluded that there were few changes in the floristic composition of the weed community according to the epoch of the phytosociological surveys. The main weed plants at 20 DAS of cowpea (vegetative phase) were Chamaesyce hirta, Digitaria insularis, Alternanthera tenella, Cleome affinis, Mollugo verticillata and Portulaca oleracea. At 40 days (reproductive phase), the weed species with a large establishment and acting as potential competitors with cv. BRS Novaera cowpea were Digitaria insularis, Chamaesyce hirta and Mollugo verticillata.

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Floristic composition of weeds in a dystrophic Red-Yellow Argisol under the cultivation of cowpea, cv. BRS Novaera.

Objetivou-se com este trabalho caracterizar plantas daninhas em area rotacionada de milho e feijao-caupi em sistema de plantio direto. As coletas foram realizadas quatro meses apos a colheita do milho. Para amostragem, utilizou-se quadrado de ferro vazado, 0,50 • 0,50 m, lancado aleatoriamente vinte e cinco vezes na area experimental com 1508 m 2 . As plantas daninhas foram identificadas e quantificadas por meio do somatorio das amostras obtidas pelo lancamento do quadrado. As variaveis avaliadas compreenderam: frequencia, densidade, abundância, frequencia relativa, densidade relativa, abundância relativa e indice de valor de importância das especies. Foram descritas as classes botânicas, familias, especies, tipo de propagacao, ciclo de vida e habito de crescimento. Na area experimental foram identificadas 38 especies, distribuidas em 7 familias, sua maioria (68,4%) a classe botânica das Dicotiledoneas. Houve predominância das familias Fabaceae (28,9%) e Poaceae (26,3%). As especies que apresentaram maior indice de valor de importância, foram: Digitaria horizontalis com 44,66% precedida da Cyperus flavus com 34,13%, Digitaria insulares com 22,87%, Cyperus sp. com 16,18% e Brachiaria plantaginea com IVR de 14,75%, que apresentam importância da mesma ordem de grandeza e devem ser igualmente consideradas na estrategia de manejo.

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Caracterização de plantas daninhas em área rotacionada de milho e feijão-caupi em plantio direto

A fitossociologia e o estudo floristico e estrutural das especies vegetais, desempenhando um papel bastante importante para o manejo das Plantas Daninhas. Objetivou-se com este trabalho estudar a fitossociologia e caracteristicas morfologicas de plantas daninhas apos cultivo de milho em plantio convencional no cerrado de Roraima. O trabalho foi realizado em area preparada em sistema de cultivo convencional por cinco anos, sendo a avaliacao realizada apos cultivo com milho. As coletas
foram realizadas quatro meses apos a colheita, durante os meses de maio a junho de 2010. Para amostragem, utilizou-se quadrado de ferro, 0,50 x 0,50 m, lancado aleatoriamente oito vezes na area experimental (45 m2). As plantas daninhas foram identificadas e quantificadas por meio do somatorio das amostras obtidas pelo lancamento do quadrado. As variaveis avaliadas compreenderam: frequencia, densidade, abundância, frequencia relativa, densidade relativa, abundância relativa e indice de valor de importância das especies. Foram, ainda, descritas as classes botânicas, familias, especies, tipo de propagacao, ciclo de vida e habito de crescimento. Na area experimental foram identificadas dezenove especies de plantas daninhas, divididas em nove familias botânicas, sendo as Fabaceae e Poaceae com maiores ocorrencias. Das especies de plantas daninhas, um percentual de 63,15% pertencem a classe botânica das Dicotiledoneas. A Sida rhombifolia foi a unica especie que foi encontrada em todas as coletas amostrais e Cenchrus echinatus foi a especie mais abundante. As especies que apresentaram maior indice de valor de importância, foram: Cenchrus echinatus, Sida rhombifolia, Digitaria sanguinalis e Cyperus rotundus.

https://revista.ufrr.br/agroambiente/article/download/1392/1187

Fitossociologia e características morfológicas de plantas daninhas após cultivo de milho em plantio convencional no cerrado de Roraima.

O feijao-caupi e uma fabacea bastante cultivada no Brasil, principalmente nas regioes Norte e Nordeste. Entretanto, a produtividade desta cultura e baixa, e dentre os fatores que contribuem para a baixa produtividade esta a interferencia causada pelas plantas daninhas. O manejo quimico das plantas e um metodo de manejo promissor, embora haja poucas informacoes para o feijao-caupi. Objetivou-se com este trabalho avaliar a seletividade de herbicidas aplicados em pre e pos-emergencia do feijao-caupi na Savana Amazonica. Foram instalados dois experimentos, um com aplicacao de oito herbicidas em pre-emergencia e outro com aplicacao de oito herbicidas em pos-emergencia, mais um tratamento com capina e outro sem capina, totalizando dez tratamentos em cada experimento. Foram avaliados os seguintes parâmetros: Fitotoxicidade, numero de vagens por planta, numero de graos por vagem, massa de 100 graos e produtividade. O herbicida metribuzin nao e recomendado em pre-emergencia na cultura do feijao-caupi, por nao ser seletivo a esta cultura, assim como os pos-emergentes fomezafen, imazethapyr, imazamox, quizalofop-p-ethyl + imazethapyr.Os herbicidas oxadiazon, em pre-emergencia, e quizalofop-p-ethyl + imazamox, em pos-emergencia, sao recomendados como estrategias de controle de plantas daninhas no feijao-caupi, por serem seletivos a cultura, nao apresentando fitotoxicidade e nao reduzindo a produtividade.Palavras-chave: controle quimico, plantas daninhas, produtividade, Vignaunguiculata. SELECTIVITY OF PRE AND POST-EMERGENCY HERBICIDES APPLIED COWPEA IN THE AMAZON SAVANNAH ABSTRACT: Cowpea is a well-grown fabaceae in Brazil, mainly in the North and Northeast regions. However, the productivity of this crop is low, and among the factors that contribute to lower productivity is the interference caused by weeds. The chemical management of plants is a promising management method, although there is little information for cowpea. The objective of this work was to evaluate the selectivity of herbicides applied in pre and post emergence of cowpea in the Amazon Savannah. Two experiments were applied, one with application of eight herbicides in pre-emergence and the other with application of eight herbicides in the post-emergence, one treatment with weeding and another treatment without weeding, totalizing ten treatments in each experiment. The following parameters were evaluated: Phytotoxicity, number of pods per plant, number of grains per pod, mass of 100 grains and productivity. The herbicide metribuzin is not recommended in pre-emergence in cowpea because it is not selective to this crop, as well as the post-emergent fomezafen, imazethapyr, imazamox, quizalofop-p-ethyl + imazethapyr. Pre-emergence oxadiazon and post-emergence quizalofop-p-ethyl + imazamox herbicides are recommended as weed control strategies in cowpea because they are selective to the crop, not presenting phytotoxicity and not reducing productivity.Keywords: chemical control, weed, Vigna unguiculata, productivity.

https://periodicoscientificos.ufmt.br/ojs/index.php/nativa/article/download/5732/4925

Seletividade de herbicidas aplicados em pré e pós-emergência na cultura do feijão-caupi na savana amazônica

A densidade de plantas pode maximizar o potencial produtivo de variedades de milho melhoradas, uma vez que, em geral, estas apresentam porte mais baixo e arquitetura foliar mais ereta. Objetivou-se com esse trabalho avaliar o efeito de tres densidades de plantios nos componentes de producao do milho transgenico hibrido Pioneer 30F35HR cultivado na savana de Roraima. O experimento foi conduzido na area experimental do Centro de Ciencias Agrarias da Universidade Federal de Roraima, no Campus do Cauame, no municipio de Boa Vista, Roraima, Brasil. O milho foi plantado em sistema de plantio direto. O delineamento experimental utilizado foi de blocos ao acaso com tres tratamentos e oito repeticoes. Os tratamentos consistiram de tres espacamentos entre plantas: 0,33; 0,25; e 0,20 m. As linhas de plantio foram espacadas de 0,80 m, resultando em uma populacao de 37.500, 50.000 e 62.500 plantas ha-1, respectivamente. As avaliacoes das caracteristicas morfologicas e agronomicas das plantas de milho foram feitas aos 70 e 100 dias apos o plantio. Os valores medios do numero da folha da insercao da primeira espiga, altura da insercao da primeira espiga, altura da folha bandeira, altura total da planta, numero de folhas totais, numero de folhas verdes e numero de folhas depois da primeira espiga do milho hibrido transgenico Pioneer 30F35HR nao sao influenciados pelo aumento da densidade de plantio entre 37.500 e 62.500 plantas ha-1. O aumento da densidade de plantio de 37.500 para 62.500 plantas ha-1 reduz a qualidade da espiga do milho, mas eleva a biomassa total e a produtividade de graos.

https://revista.ufrr.br/agroambiente/article/download/1543/1195

José de Anchieta Alves Albuquerque

Papers

Caracterização de plantas daninhas em área rotacionada de milho e feijão-caupi em plantio direto

Fitossociologia e características morfológicas de plantas daninhas após cultivo de milho em plantio convencional no cerrado de Roraima.

Seletividade de herbicidas aplicados em pré e pós-emergência na cultura do feijão-caupi na savana amazônica

Produção do milho híbrido 30F35HR cultivado na savana de Roraima em diferentes densidades de plantio.