Barra de Santo Antônio, Brazil
Barra de Santo Antônio, Brazil

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Petter F.A.,Federal University of Piauí | Madari B.E.,Embrapa Arroz e Feijao
Revista Brasileira de Engenharia Agricola e Ambiental | Year: 2012

Due to the high activity of microorganisms, the loss of soil organic matter is high in tropical regions. This loss becomes even greater if the soil is managed improperly or when there is no technology that leverages the permanence of the soil carbon by maintaining appropriate levels of organic matter, providing chemical, physical and biological soil improvements and contributing to reduce CO2 emissions to the atmosphere. Due to its aromatic structure, biochar is a highly stable form of carbon in the soil that may contribute to the reduction of greenhouse gas emissions, such as CO2, N2O and CH4, and act as a soil conditioner, improving the physical and chemical properties of the soil. Biochar may also result in increased productivity due to the improvement of soil attributes or a possible electrophysiological effect. Research over the past decades has demonstrated the potential of biochar as a soil conditioner, improving fertility and nutrient-use efficiency, in addition to maximising the productivity of crops, such as soybean and rice.


Pessoa-Filho M.,University of Brasilia | Rangel P.H.N.,Embrapa Arroz e Feijao | Ferreira M.E.,Genetics Laboratory
BMC Plant Biology | Year: 2010

Background: Breeding programs are usually reluctant to evaluate and use germplasm accessions other than the elite materials belonging to their advanced populations. The concept of core collections has been proposed to facilitate the access of potential users to samples of small sizes, representative of the genetic variability contained within the gene pool of a specific crop. The eventual large size of a core collection perpetuates the problem it was originally proposed to solve. The present study suggests that, in addition to the classic core collection concept, thematic core collections should be also developed for a specific crop, composed of a limited number of accessions, with a manageable size.Results: The thematic core collection obtained meets the minimum requirements for a core sample - maintenance of at least 80% of the allelic richness of the thematic collection, with, approximately, 15% of its size. The method was compared with other methodologies based on the M strategy, and also with a core collection generated by random sampling. Higher proportions of retained alleles (in a core collection of equal size) or similar proportions of retained alleles (in a core collection of smaller size) were detected in the two methods based on the M strategy compared to the proposed methodology. Core sub-collections constructed by different methods were compared regarding the increase or maintenance of phenotypic diversity. No change on phenotypic diversity was detected by measuring the trait "Weight of 100 Seeds", for the tested sampling methods. Effects on linkage disequilibrium between unlinked microsatellite loci, due to sampling, are discussed.Conclusions: Building of a thematic core collection was here defined by prior selection of accessions which are diverse for the trait of interest, and then by pairwise genetic distances, estimated by DNA polymorphism analysis at molecular marker loci. The resulting thematic core collection potentially reflects the maximum allele richness with the smallest sample size from a larger thematic collection. As an example, we used the development of a thematic core collection for drought tolerance in rice. It is expected that such thematic collections increase the use of germplasm by breeding programs and facilitate the study of the traits under consideration. The definition of a core collection to study drought resistance is a valuable contribution towards the understanding of the genetic control and the physiological mechanisms involved in water use efficiency in plants. © 2010 Pessoa-Filho et al; licensee BioMed Central Ltd.


Aragao F.J.L.,Embrapa Recursos Geneticos e Biotecnologia | Nogueira E.O.P.L.,Embrapa Recursos Geneticos e Biotecnologia | Tinoco M.L.P.,Embrapa Recursos Geneticos e Biotecnologia | Faria J.C.,Embrapa Arroz e Feijao
Journal of Biotechnology | Year: 2013

Golden mosaic of common bean is caused by the Bean golden mosaic virus (BGMV). The disease is one of the greatest constraints on bean production in Latin America and causes significant yield losses. The RNAi concept was explored to silence the rep (AC1) viral gene and a transgenic bean line immune to BGMV upon inoculation at high pressure was previously generated. Identification of the transgene insert confirmed the presence of a single locus corresponding to two intact copies of the RNAi cassette in opposite orientation and three intact copies of the AtAhas gene. It is flanked by Phaseolus genomic sequences and interspersed by one nuclear and three chloroplastic genomic sequences. Southern analyses showed that the transgenes were structurally stable for eight self-pollinated generations and after backcrosses with a non transgenic commercial variety. Transgene expression analyses revealed similar levels of siRNA in leaves of transgenic plants cultivated under field conditions in three distinct regions. siRNA were also analyzed during seed development in common bean transgenic plants. siRNA signals were also detected in seeds, albeit at significantly lower levels than those observed in leaves, and could not be detected in seeds cooked during 10. min. This information is relevant to demonstrate that GM beans are free of siRNA signals after cooking and therefore suitable for human consumption. Additionally, characterization of the locus where the transgene was integrated in the common bean genome provides a valuable tool to trace this GM bean material in the field and in the market. © 2013 Elsevier B.V.


Water deficit is one of the most important abiotic stress limiting upland rice yield in the "Cerrado" region of Brazil. Selecting drought tolerant cultivars is an important strategy to overcome this constraint. Two greenhouse experiments were conducted at Santo Antônio de Goiás, state of Goiás, Brazil, to compare the response of normalized transpiration rate (NTR) of three modern (BRS Primavera, BRSMG Curinga and BRS Soberana) and one traditional (Douradão) upland rice cultivars to soil water deficit during the vegetative and reproductive growth stages. This information will support breeding strategies to improve rice yield in a drought-prone target population environments (TPE) in Brazil. NTR and the total fraction of transpirable soil water (FTSW) were calculated, plotted and adjusted according to a sigmoid non-linear model. The p factor, defined as the fraction of available soil water that can be removed from the root zone before water deficit occurs, was calculated by assuming that it occurs when NTR is equal to 0.95. Modern cultivars had a higher value of p for the reproductive phase than for the vegetative phase. In addition, these cultivars are better adapted to express their potential yield in regions with low intensity and occurrence of water stress and the traditional cultivar is enable to better support adverse conditions of water stress. It can be concluded that there is need to precisely characterize drought patterns in TPEs. This information can focus the breeding program to improve drought tolerance in modern upland rice cultivars.


Breseghello F.,Embrapa Arroz e Feijao | Coelho A.S.G.,Federal University of Goais
Journal of Agricultural and Food Chemistry | Year: 2013

Plant breeding can be broadly defined as alterations caused in plants as a result of their use by humans, ranging from unintentional changes resulting from the advent of agriculture to the application of molecular tools for precision breeding. The vast diversity of breeding methods can be simplified into three categories: (i) plant breeding based on observed variation by selection of plants based on natural variants appearing in nature or within traditional varieties; (ii) plant breeding based on controlled mating by selection of plants presenting recombination of desirable genes from different parents; and (iii) plant breeding based on monitored recombination by selection of specific genes or marker profiles, using molecular tools for tracking within-genome variation. The continuous application of traditional breeding methods in a given species could lead to the narrowing of the gene pool from which cultivars are drawn, rendering crops vulnerable to biotic and abiotic stresses and hampering future progress. Several methods have been devised for introducing exotic variation into elite germplasm without undesirable effects. Cases in rice are given to illustrate the potential and limitations of different breeding approaches. © 2013 American Chemical Society.


Faria J.C.,Embrapa Arroz e Feijao
GM crops | Year: 2010

Gene flow is a common phenomenon even in self-pollinated plant species. With the advent of genetically modified plants this subject has become of the utmost importance due to the need for controlling the spread of transgenes. This study was conducted to determine the occurrence and intensity of outcrossing in transgenic common beans. In order to evaluate the outcross rates, four experiments were conducted in Santo Antonio de Goiás (GO, Brazil) and one in Londrina (PR, Brazil), using transgenic cultivars resistant to the herbicide glufosinate ammonium and their conventional counterparts as recipients of the transgene. Experiments with cv. Olathe Pinto and the transgenic line Olathe M1/4 were conducted in a completely randomized design with ten replications for three years in one location, whereas the experiments with cv. Pérola and the transgenic line Pérola M1/4 were conducted at two locations for one year, with the transgenic cultivar surrounded on all sides by the conventional counterpart. The outcross occurred at a negligible rate of 0.00741% in cv. Pérola, while none was observed (0.0%) in cv. Olathe Pinto. The frequency of gene flow was cultivar dependent and most of the observed outcross was within 2.5 m from the edge of the pollen source. Index terms: Phaseolus vulgaris, outcross, glufosinate ammonium.


Sant'Ana E.V.P.,Instituto Federal Of Educacao | dos Santos A.B.,Embrapa Arroz e Feijao | da Silveira P.M.,Embrapa Arroz e Feijao
Revista Brasileira de Engenharia Agricola e Ambiental | Year: 2011

Nitrogen fertilization is one of the management techniques necessary to achieve high yield potential in irrigated agricultural systems. The objective of this study was to evaluate effects of nitrogen applied as topdressing on phytobiomass and nutrient use efficiency in dry bean cultivar BRS Horizonte. The experiment was conducted at the National Rice and Beans Research Center of Embrapa in a Distrophic Red Latosol in randomized block design with four replications. The nitrogen rates used were 0, 30, 60, 120 and 240 kg ha-1, half applied 10 days after plant emergence and half, 17 days after plant emergence in the form of urea. Dry bean phytobiomass was linearly related with N rate at flowering, while at harvest the response was quadratic. Relation between grain harvest index, nitrogen harvest index and N rate was quadratic and the maximum index was obtained at 140 kg N ha-1. Nitrogen use efficiency by dry bean varied with N rate applied and type of efficiency while agronomical and physiological efficiencies decreased with increase N rates.


Andrade R.S.,ALC n. 14 | Stone L.F.,Embrapa Arroz e Feijao
Revista Brasileira de Engenharia Agricola e Ambiental | Year: 2011

The objective of this study was to estimate the soil moisture at field capacity (θfc) by an equation based on the soil water retention curve (SWRC) and by correlation with physico-hydrical attributes and data from texture and organic matter for very clayey, clayey, loamy, and sandy soils. The study was carried out with 2242 samples from 'Cerrado' soils, which contained information on textural classification, physical attributes and soil water retention. For 745 samples, there was information on the saturated hydraulic conductivity (Ko) and for 472, on clay, silt, sand and organic matter contents. For samples with measured Ko, θfc was determined based on parameters of the equation of Genuchten (1980), assuming that the drainage rate (τ) is a percentage p of Ko. p values of 0.0025, 0.0050, 0.0100, 0.0150, and 0.0200 were considered. It was observed that θfc can be estimated by the equation based on SWRC, considering τ as 1% of the Ko value. θfc can also be estimated as a function of moisture at the inflection point of SWRC and soil porosity for each soil horizon. The soil water tension corresponding to θfc was between 6.5 and 7.5 kPa, for τ equivalent to 1% of the Ko value.


Nascente A.S.,Embrapa Arroz e Feijao | Crusciol C.A.C.,São Paulo State University
Pesquisa Agropecuaria Brasileira | Year: 2012

The objective of this work was to evaluate the effect of cover crops and timing of pre-emergence herbicide applications on soybean yield under no-tillage system. The experiment consisted of four cover crops (Panicum maximum, Urochloa ruziziensis, U. brizantha, and pearl millet) and fallow, in addition to four herbicide timings (30, 20, 10, and 0 days before soybean sowing), under no-tillage system (NTS), and of two control treatments under conventional tillage system (CTS). The experimental design was a completely randomized block, in a split-plot arrangement, with three replicates. Soybean under fallow, P. maximum, U. ruziziensis, U. brizantha, and pearl millet in the NTS and soybean under U. brizantha in the CTS did not differ significantly regarding yield. Soybean under fallow in the CTS significantly reduced yield when compared to the other treatments. The amount of straw on soil surface did not significantly affect soybean yield. Chemical management of P. maximum and U. brizantha near the soybean sowing date causes significant damage in soybean yield. However, herbicide timing in fallow, U. ruziziensis, and pearl millet does not affect soybean yield.


Nascente A.S.,Embrapa Arroz e Feijao | Crusciol C.A.C.,São Paulo State University | Cobucci T.,Embrapa Arroz e Feijao
Pesquisa Agropecuaria Brasileira | Year: 2012

The objective of this work was to evaluate the effect of cover crops and their desiccation times on upland rice yield and on the levels of nitrate and ammonium in a no-tillage soil. The experiment was carried out in a randomized blocks, with split plots and three replicates. Cover crops (plots) were sowed in the offseason (March 2009). In November 2009, at 30, 20, 10 and 0 days before rice sowing (split plots), herbicide was applied on the cover crops (fallow, Panicum maximum, Urochloa ruziziensis, U. brizantha and millet). Straw and soil were sampled (0-10 cm) at the sowing day, and after 7, 14, 21, 28 and 35 days. Straws from millet and fallow were degraded more rapidly and provided the lowest level of nitrate in the soil. Urochloa ruziziensis, U. brizantha and P. maximum produced higher amounts of dry matter, and provided the highest levels of nitrate in the soil. Millet provides the lowest nitrate/ammonium ratio and the highest upland rice yield. Desiccations carried out at 30 and 20 days before sowing had the largest levels of nitrate in the soil at the sowing date. Nitrogen content and forms in the soil are affected by cover crops and their desiccation times.

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