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da Silva A.A.,Instituto Rio Grandense do Arroz IRGA | Delatorre C.A.,Federal University of Rio Grande do Sul | de Moraes M.G.,Federal University of Rio Grande do Sul
Ciencia Rural | Year: 2011

Biological systems are governed by the sum of all expressed genes, proteins, metabolites and components of an organism. The analysis of a tissue ionome helps to identify, among others, genes that contribute to a greater or lesser accumulation of essential elements and heavy metals, as well as interaction between metabolic processes. The ionome knowledge, coupled with the use of molecular biology techniques, form a very efficient system for gene mapping, and functional genomic studies, and general characterization of plants physiological status in a given condition. Another interesting process that the ionome study allows to analyse is the interactions among plants' ions and how such ion availability can affect the absorption and use of others. The aim of this review is to present and discuss the ionome as an important tool in the elucidation of several mechanisms involved in absorption, translocation and accumulation of essential and nonessential elements in plant and its relation with their metabolism.


Macedo V.R.M.,Instituto Rio Grandense do Arroz IRGA | da Silva A.J.N.,Federal University of Rio Grande do Norte | Cabeda M.S.V.,Federal University of Rio Grande do Sul
Revista Brasileira de Engenharia Agricola e Ambiental | Year: 2010

The objectives of this study were to determine the compressibility parameters of an Acrisol through uniaxial compression tests, with three application times of compressive pressure (7.5 s, 1 and 2 min) and in two moisture contents (0.113 and 0.164 kg kg -1), and to verify the mechanical soil behavior after the removal of the loads. The Acrisol was collected in an experiment conducted in areas physically degraded and upgraded, in the Agricultural Experimental Station of the UFRGS. The physically degraded condition presented the highest values of precompaction pressure in relation to the upgraded condition, for both moisture contents. There was no significant difference among the values of precompaction pressure determined with the soil compression curve for the times of 7.5 s, 1 and 2 min compressive pressure application in both moisture contents as well in both physical conditions of the soil. The physically upgraded condition presented higher compression index compared to the degraded condition in both moisture contents. The relief promoted by the removal of the compressive pressures imposed on the soil promoted a small increment in the total porosity and reduction in the bulk density.


Stein R.J.,Federal University of Rio Grande do Sul | Stein R.J.,Ruhr University Bochum | Lopes S.I.G.,Instituto Rio Grandense do Arroz IRGA | Fett J.P.,Federal University of Rio Grande do Sul
Theoretical and Experimental Plant Physiology | Year: 2014

Iron toxicity is a major nutritional disorder in irrigated and rainfed waterlogged rice. To elucidate mechanisms involved in tolerance to iron toxicity, plants from one cultivar susceptible to iron toxicity (BR-IRGA 409) and two tolerant cultivars (EPAGRI 108 and EPAGRI 109) were grown in the field, at an iron-toxic site and at a control site in Southern Brazil. We evaluated chlorophyll concentrations, carbonyl concentrations, iron concentrations in leaves and roots, antioxidative enzyme activities (SOD, APX, CAT, GR and DHR), concentrations of reduced and oxidized forms of ascorbate and glutathione, and gene expression profile of four SOD genes in rice leaves. Only plants from the susceptible cultivar showed symptoms of iron toxicity when grown at the iron-toxic site, accumulating high levels of iron in leaves. EPAGRI 108 plants had the lowest iron concentration in leaves and reached the highest iron concentration in the root symplast, suggesting that the capacity to safely store iron in root cells and to limit iron translocation to shoots could be a tolerance mechanism in this cultivar. Plants from the susceptible cultivar showed higher APX activity as well as higher DHA and GSSG concentrations. Plants from the EPAGRI 109 cultivar accumulated high iron levels in leaves, and showed the highest SOD, GR and DHR activities when grown in the iron-toxic site. The same cultivar also showed the highest expression of three out of four SOD genes tested. Therefore, the two tolerant cultivars seem to rely on different mechanisms to deal with iron toxicity in field conditions: limiting iron translocation to the shoot or inducing enzymes-dependent leaf tolerance. © 2014 Brazilian Society of Plant Physiology.


Carmona F.C.,Instituto Rio Grandense do Arroz IRGA | Anghinoni I.,Federal University of Rio Grande do Sul | Holzschuh M.J.,Federal University of Rio Grande do Sul | Martins A.P.,Federal University of Rio Grande do Sul
Revista Brasileira de Ciencia do Solo | Year: 2011

Soils of the coastal plains of Rio Grande do Sul, Brazil, are affected by salinization, which can hamper the establishment and development of crops in general, including rice. The application of high doses of KCl may aggravate the crop damage, due to the high saline content of this fertilizer. This study aimed to evaluate the effect of K fertilizer management on some properties of rice plant, grown in soils with different sodicity levels, and determine which attribute is best related to yield. The field study was conducted in four Albaqualfs with exchangeable Na percentages of 5.6, 9.0, 21 and 32 %. The management of KCl fertilizer consisted of the application of 90 kg ha-1 K 2O broadcast, 90 kg ha -1 K 2O in the row and 45 kg ha -1 K 2O in the row + 45 kg ha -1 K 2O at panicle initiation (PI). Plant density, dry matter evolution, height, SPAD (Soil Plant Analysis Development value indicating relative chlorophyll contents) index, tiller mass, 1,000-grain weight, panicle length and grain yield were evaluated. The plant density was damaged by application of K fertilizer in the row, especially at full dose (90 kg ha -1), at three sodicity levels, resulting in loss in biomass accumulation in later stages, affecting the crop yield, even at the lowest level of soil sodicity (5.6 %). All properties were correlated with yield; the highest positive correlation was found with plant density and shoot dry matter at full flowering, and a negative correlation with panicle length.


Marchesan E.,Federal University of Santa Maria | Sarzi Sartori G.M.,Federal University of Santa Maria | de Avila L.A.,Federal University of Santa Maria | Machado S.L.O.,Federal University of Santa Maria | And 4 more authors.
Ciencia Rural | Year: 2010

The rice-growing activity is conducted out with intensive use of agrochemicals, which, depending on the management and rainfall can reach rivers. The study aimed to determine the residues of herbicides clomazone, quinclorac, propanil, bentazone, 2,4-D and imazethapyr and insecticides carbofuran and fipronil in the Vacacaí and Vacacaí-Mirim rivers, located in the Central Depression of Rio Grande do Sul, in the crop of 2003/04 untill 2007/08. Samples were collected from November to February (rice growing season). Analysis of herbicides and carbofuran were performed by HPLC-DAD and fipronil by GC-ECD. During 2003/04, in both rivers, the herbicide clomazone, 2,4-D and propanil were the most frequent in water samples. In 2004/05, the quinclorac was detected in many samples and in 2005/06 and 2006/07 season's fipronil was the most common pesticide in the samples in Vacacaí and Vacacaí-Mirim rivers. In the 2007/08 crop, there were less residues of pesticides in Vacacaí and Vacacaí-Mirim rivers. There is presence of pesticides used in rice farming in the Vacacaí and Vacacaí-Mirim rivers during the rice crop, especially among those analyzed, the herbicides clomazone and quinclorac and the insecticide fipronil.


The objective of this work was to evaluate the selectivity of residual herbicides applied at increasing rates, under pre-emergence condition, to common bean crop (Phaseolus vulgaris) during the early period of the vegetative phase. The experiment was arranged in a randomized design under greenhouse conditions, with the treatments in a two-factorial scheme, using five replicates per treatment. The common bean cultivar IPR Graúna was used as a reagent of the treatments. Factor A was composed by the herbicides, and Factor B, by the rates. The herbicides were alachlor, dimethenamid, S-metolachlor, pendimethalin, and trifluralin, and the rates corresponded to 0, 100, 150, 200, and 300% of the maximum label rate for use in the common bean. The variables applied were plantlet emergence, visual intoxication and dry mass of the common bean, respectively, at 05, 20, and 25 days after emergence. Alachlor was not selective to the common bean, while dimethenamid, S-metolachlor, pendimethalin, and trifluralin were selective when sprayed up to the maximum rate. The level of selectivity of dimethenamid and S-metolachlor varied with the rate applied, while the level of selectivity of trifluralin and pendimethalin did not change.


This work evaluated the effects of residual herbicides, applied in crop pre-emergence, on the reduction of Alexander grass (Urochloa plantaginea) infestation in the common bean. Two field experiments were conducted at Eldorado do Sul, RS/Brazil: one using the bean cultivar UFT-06 (Red group), and the other using IPR Graúna (Black group). The experiments were arranged in a randomized block design, with four replicates, and the treatments consisted of four herbicides, at two rates (kg i.a. ha-1), as follows: pendimethalin and trifluralin (1.2 and 1.4), and s metolachlor and dimethenamid (1.4 and 1.6). Control and shoot mass of Alexander grass were assessed at 20 and 40 days after crop emergence, which includes the critical period of weed interference. All residual herbicides reduced Alexander grass infestation during this period, and the best weed control was obtained with trifluralin herbicide in both experiments. To successfully reduce Alexander grass infestation with residual herbicides, weed management actions must be taken during common bean post-emergence.


Genro Jr. S.A.,Instituto Rio Grandense do Arroz IRGA | Marcolin E.,Instituto Rio Grandense do Arroz IRGA | Anghinoni I.,Federal University of Rio Grande do Sul
Revista Brasileira de Ciencia do Solo | Year: 2010

As a result of high flooded rice yields obtained in more recent years and the high crop response to fertilization in southern Brazil, fertilizer recommendations were flexibilized to meet different yield expectations. As these recommendations were poorly supported by research results, this study was conducted to evaluate the efficacy of these recommendations for the dryseeded rice system in the rice cultivation regions of the State. Thirteen field experiments were conducted at nine locations: four in the 2004/2005 and nine in the 2005/2006 growing seasons with the following treatments: 1. Control (without fertilization); 2. Recommendation to acchieve yield up to 6.0 Mg ha-1); 3. For yields of 6.0-9.0 Mg ha-1; 4. For yields of 9.0-12.0 Mg ha-1), and 5. For yields of more than 12.0 Mg ha-1). Treatments 2, 3, and 4 represent the official regional fertilizer recommendations for flooded rice. The applied fertilizer rates were defined by the soil fertility status of each location, and treatments were distributed in randomized blocks. Fertilizer recommendations for dry-seeded flooded rice, in spite of resulting in relevant and consistent yield increases (average of 3.2 Mg ha-1), did not achieve the expected yields, which depend on the soil and climate conditions of each location.


Moterle D.F.,Federal University of Rio Grande do Sul | da Silva L.S.,Federal University of Santa Maria | Moro V.J.,Federal University of Santa Maria | Bayer C.,Federal University of Rio Grande do Sul | And 3 more authors.
Revista Brasileira de Ciencia do Solo | Year: 2013

Paddy rice fields may contribute to methane (CH4) emission from soil due to anaerobic conditions after flooding. Alternatives to continuous flooding irrigation in rice have been developed to mitigate CH4 efflux into the atmosphere. This study aims to investigate the effects of irrigation managements in the CH4 efflux during the rice growing season. An experiment was carried out at in Santa Maria, Rio Grande do Sul State, Brazil, during 2007/08 and 2009/10 growing seasons. The treatments were continuous flooding and intermittent irrigation in 2007/08 and continuous flooding, intermittent irrigation and flush irrigation in 2009/10. Intermittent irrigation is effective in mitigating CH4 efflux from rice fields when climatic conditions enable water absence during cultivation, but its efficiency depends on the electrochemical soil conditions during the flooding cycles.


Massoni P.F.S.,Instituto Rio Grandense do Arroz IRGA | Marchesan E.,Federal University of Santa Maria | Grohs M.,Empresa de Assistencia Tecnica e Extensao Rural EMATER | da Silva L.S.,Federal University of Santa Maria | Roso R.,Federal University of Santa Maria
Revista Ciencia Agronomica | Year: 2013

After harvesting irrigated rice, the straw produced can be managed in different ways, and these may affect the availability of soil nutrients. The objective of this work was to evaluate the effect of different types of soil and straw management, carried out after the rice is harvested, on the levels of mineral nitrogen, phosphorus and potassium available in the soil,. The treatments were arranged in randomized blocks with plot evaluations split up in time, and corresponding to seven different types of soil management: [1] water at a constant depth, without straw, [2] straw incorporated into the preparation of dry soil immediately after harvest, [3] straw incorporated into the preparation of flooded soil immediately after harvest, [4] straw incorporated into the preparation of dry soil during July only, [5] straw incorporated into the preparation of flooded soil immediately after harvest, and then harrowing the area with dry soil in July, [6] straw incorporated into the preparation of dry soil immediately after harvest, and harrowing the area with dry soil in July, [7] no incorporated straw and no water. Evaluations were made on five different soil-collection dates, with four replications. Keeping straw on the soil surface produced the greatest variations in the concentrations of mineral nitrogen for the period studied, however, regardlesss of the post-harvest rice-straw managn the levels of mineral nitrogen, phosphorus and potassium available in the soil by the end of the season.

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