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Da Silva E.A.J.,Instituto Federal Goiano IFG | Da Silva V.P.,Instituto Federal Goiano IFG | Alves C.C.F.,Instituto Federal Goiano IFG | Alves J.M.,Instituto Federal Goiano IFG | And 2 more authors.
Ciencia Rural | Year: 2016

The essential oil plants contents can be affected by several factors. For example, in certain plants, collection time has been observed to affect the content and chemical composition of the essential oil obtained from the plant. The objective of this study was to evaluate the effect of collection time on the content and chemical composition of the essential oil from guava (Psidium guajava L.) leaves. Leaves were collected at different times of the day and the content and chemical composition of their essential oil was determined. Collection time did not qualitatively affect the chemical composition of the essential oil. However, concentration of certain substances in the oil, such as α-humulene and trans-caryophyllene, did significantly vary at different collection times. The main constituents of the essential oil of Psidium guajava are limonene (2.2-4.4%), trans-caryophyllene (18.1-17.1%), α-humulene (26.3-20.4%), aromadendrene (7.6-12.2%), α-selinene (7.3-11.3%), caryophyllene oxide (3.7-3.3%), humulene epoxide II (4.1-1.9%), and selin-11-en-4α-ol (7.2-11.1%). Leaves collected at 7:00 AM had higher essential oil production, with a content of 0.38% (d.b.), whereas leaves collected at 7:00 PM had lower essential oil production, 0.24% (d.b.). Chemical analysis showed that sesquiterpene compounds represented the highest concentration (62.0%), and monoterpenoids and monoterpenes represented the lowest concentrations (1.1 and 2.2%, respectively). Chemical classes that underwent major changes with respect to collection time were monoterpenes, sesquiterpenes, and sesquiterpenoids (2.2-4.4%, 63.8-61.7%, and 15.9-13.2%, respectively). © 2016 Ciencia Rural. All rights reserved.

Garcia R.A.,Fundacao de Ensino Superior de Goiatuba | Miranda B.A.,Federal University of Goais | Lobo Junior M.,Embrapa Arroz e Feijao | Araujo F.G.,Instituto Federal Goiano IFG | Cunha M.G.,Federal University of Goais
Bioscience Journal | Year: 2014

The soil inhabiting fungi, Rhizoctonia solani and Fusarium solani f.sp. phaseoli, constitute an etiological complex with synergic interaction, responsible for up to 50% losses in common beans. Organic matter of diverse sources is used in agriculture to stimulate microbial activity limiting the activity of soil inhabiting plant pathogens, among other uses. This study evaluated the effect of organic compound doses on root rots caused by R. solani and F. solani f.sp. phaseoli, in common beans, cultivar Pérola, in field conditions. The experimental design was randomized blocks, as a 2 × 6 factorial. The organic compounds of Crotalaria juncea or Paspalum notatum, associated with poultry bedding, were applied in the planting furrow at the doses de 0, 20, 40, 80, 160 or 320 kg.ha-1. Evaluations of severity were done using a rating scale. Greater severity of F. solani f.sp. phaseoli in common bean plants were observed at the dose of 320 kg.ha-1 crotalaria + poultry bedding e 80 kg.ha-1 with paspalum compound + poultry bedding. The organic compounds and doses did not affect R. solani severity. The dose of 80 kg.ha-1, regardless of the organic compound, resulted in greater yield.

Vegetation indices obtained by remote sensing products have various applications in agriculture. An important application of the Normalized Difference Vegetation Index (NDVI) is obtaining the crop coefficient (Kc). The aims of this study were to analyze NDVI temporal profiles and to obtain Kc from the NDVI vegetation index product MOD13Q1. The analysis is based on the phenological stages of irrigated soybean crops in the municipality of Planura/MG during the 2010/2011 growing season. Areas planted with irrigated soybean were identified through fieldwork. Temporal series of the MOD13Q1 products were used to analyze NDVI, allowing the extraction of NDVI values for all points in the period studied. The NDVI temporal profiles showed a similar pattern to each other and corresponded to the crop cycle. The KcNDVI values for the MOD13Q1 products were well correlated to the FAO Kc values (r2=0.72). Thus, NDVI can be used as an alternative for obtaining crop coefficient (Kc). © 2016, Universidade Federal de Santa Maria. All rights reserved.

The aim of this study was to evaluate changes in soil physical properties, specifically regarding soil aggregation and resistance to penetration, as well as total organic carbon (TOC) of an Oxisol subjected to an integrated crop-livestock system with the following coverage: corn, pasture, Tanzania grass and Savannah. Soil cultivated with Tanzania grass showed the lowest percentage of total porosity (49%), highest density of soil (Ds) in the surface layer of 0-5 cm (1.60 g kg-1), and similar to the soil cultivated with pasture, presented lower percentages of macropores (6.6 to 9.4%) and higher values of soil penetration resistance at field capacity (1.3 to 4.08 MPa). At the three depths, the TOC levels were highest in Savannah soil; and among the cultivated areas at the depth of 5-10 cm, the highest levels were observed in areas with corn (20.15 g kg-1) and pasture (23.15 g kg-1). Areas with corn and pasture showed the highest percentage of large aggregates (>4 mm), similar to the Savannah that presented the highest weighted average diameter of aggregates (WAD). A positive correlation was observed between TOC and WAD of the aggregates (r=0.45), WAD and total soil porosity (r=0.76) and a negative correlation between TOC and Ds (r=-0.56).

Benteo G.L.,Instituto Federal Goiano IFG | Verzignassi J.R.,Embrapa Gado de Corte | Fernandes C.D.,Embrapa Gado de Corte | do Valle C.B.,Embrapa Gado de Corte | And 3 more authors.
Ciencia Rural | Year: 2016

This study aimed to evaluate aspects of reproductive phenology, yield components and seed quality of the B4 genotype of Brachiaria brizantha in function of nitrogen doses applied at pre-flowering. The experiment was carried out at Embrapa Beef Cattle, in a randomized block design, with seeding density of 2.59kg SPV ha−1 in the first year, in free growth plants. Urea was applied at pre-flowering at doses of 0, 25, 50, 75, 100, 125 and 150kg ha−1. The reproductive cycle of the plant lasts 225 days, with late flowering. N doses influenced the following characteristics: number of fully expanded inflorescences, percentage of dry matter, dry biomass, number of spikelets per raceme, seed yield, weight of a thousand seeds, germination, germination speed index, viability and germination at 10 months after harvest. The maximum yield of pure seed was 144.8kg ha−1 for 50kg ha−1 N, with maximum biological potential, based on components of seed yield of 456.27kg ha−1. Seeds presented high dormancy and reduced physiological quality in higher N doses. © 2016, Universidade Federal de Santa Maria. All rights reserved.

Cabral P.H.R.,Instituto Federal Goiano IFG | Jakelaitis A.,Instituto Federal Goiano IFG | Sichierski Cardoso I.,Instituto Federal Goiano IFG | Tavares de Araujo V.,Instituto Federal Goiano IFG | Fernandes Pedrini E.C.,Instituto Federal Goiano IFG
Pesquisa Agropecuaria Tropical | Year: 2013

Sorghum has a great importance in the world economy as an energy source for food and feed. In the southwest Goiás State, although this culture has a high productive potential, its yield is low, mainly due to the interference of inadequate weed management. This research aimed at determining the periods of weed interference on off-season sorghum crop, in Rio Verde, Goiás State, Brazil. Treatments consisted of ten periods of initial control, in which the crop was kept free of weeds, and ten periods of initial coexistence with weeds. Both the initial periods of control or coexistence, after the crop emergence, were: 0-0, 0-7, 0-14, 0-21, 0-28, 0-35, 0-42, 0-49, 0-56 and 0-harvest (112 days after emergence - DAE). The most important weed species present in the experimental area were Amaranthus lividus, Commelina benghalensis, Bidens pilosa, Sida rhombifolia, Urochloa decumbens, Digitaria horizontalis and Portulaca oleracea. The presence of weeds reduced plant height, stem diameter, grain yield and one thousand grain weight of sorghum, with a higher interference degree for increasing periods of mutual coexistence between the weed community and sorghum. For a 5% tolerance in the reduction of sorghum yield, it was concluded that the period before the interference was up to 23 DAE, the total period of interference prevention up to 42 DAE and the critical period of interference prevention from 23 to 42 DAE.

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