Chlorophyll Fluorescence Imaging as a Tool for Evaluating Disease Resistance of Common Bean Lines in the Western Amazon Region of Colombia.

The evaluation of disease resistance is considered an important aspect of phenotyping for crop improvement. Identification of advanced lines of the common bean with disease resistance contributes to improved grain yields. This study aimed to determine the response of the photosynthetic apparatus to natural pathogen infection by using chlorophyll (Chla) fluorescence parameters and their relationship to the agronomic performance of 59 common bean lines and comparing the photosynthetic responses of naturally infected vs. healthy leaves. The study was conducted over two seasons under acid soil and high temperature conditions in the western Amazon region of Colombia. A disease susceptibility index (DSI) was developed and validated using chlorophyll a (Chla) fluorescence as a tool to identify Mesoamerican and Andean lines of common bean (Phaseolus vulgaris L.) that are resistant to pathogens. A negative effect on the functional status of the photosynthetic apparatus was found with the presence of pathogen infection, a situation that allowed the identification of four typologies based on the DSI values ((i) moderately resistant; (ii) moderately susceptible; (iii) susceptible; and (iv) highly susceptible). Moderately resistant lines, five of them from the Mesoamerican gene pool (ALB 350, SMC 200, BFS 10, SER 16, SMN 27) and one from the Andean gene pool (DAB 295), allocated a higher proportion of energy to photochemical processes, which increased the rate of electron transfer resulting in a lower sensitivity to disease stress. This photosynthetic response was associated with lower values of DSI, which translated into an increase in the accumulation of dry matter accumulation in different plant organs (leaves, stem, pods and roots). Thus, DSI values based on chlorophyll fluorescence response to pathogen infection could serve as a phenotyping tool for evaluating advanced common bean lines. Six common bean lines (ALB 350, BFS 10, DAB 295, SER 16, SMC 200 and SMN 27) were identified as less sensitive to disease stress under field conditions in the western Amazon region of Colombia, and these could serve as useful parents for improving the common bean for multiple stress resistance.

Water Use, Leaf Cooling and Carbon Assimilation Efficiency of Heat Resistant Common Beans Evaluated in Western Amazonia.

In our study, we analyzed 30years of climatological data revealing the bean production risks for Western Amazonia. Climatological profiling showed high daytime and nighttime temperatures combined with high relative humidity and low vapor pressure deficit. Our understanding of the target environment allows us to select trait combinations for reaching higher yields in Amazonian acid soils. Our research was conducted using 64 bean lines with different genetic backgrounds. In high temperatures, we identified three water use efficiency typologies in beans based on detailed data analysis on gasometric exchange. Profligate water spenders and not water conservative accessions showed leaf cooling, and effective photosynthate partitioning to seeds, and these attributes were found to be related to higher photosynthetic efficiency. Thus, water spenders and not savers were recognized as heat resistant in acid soil conditions in Western Amazonia. Genotypes such as BFS 10, SEN 52, SER 323, different SEFs (SEF 73, SEF 10, SEF 40, SEF 70), SCR 56, SMR 173, and SMN 99 presented less negative effects of heat stress on yield. These genotypes could be suitable as parental lines for improving dry seed production. The improved knowledge on water-use efficiency typologies can be used for bean crop improvement efforts as well as further studies aimed at a better understanding of the intrinsic mechanisms of heat resistance in legumes.

Physiological, nutritional, and molecular responses of Brazilian sugarcane cultivars under stress by aluminum.

BACKGROUND: Sugarcane is a crop of global importance and has been expanding to areas with soils containing high levels of exchangeable aluminum (Al), which is a limiting factor for crop development in acidic soils. The study of the sugarcane physiological and nutritional behavior together with patterns of gene expression in response to Al stress may provide a basis for effective strategies to increase crop productivity in acidic soils. METHODS: Sugarcane cultivars were evaluated for physiological parameters (photosynthesis, stomatal conductance, and transpiration), nutrient (N, P, K, Ca, Mg, and S) and Al contents in leaves and roots and gene expression, of the genes MDH, SDH by qPCR, both related to the production of organic acids, and SOD, related to oxidative stress. RESULTS: Brazilian sugarcane RB867515, RB928064, and RB935744 cultivars exhibited very different responses to induced stress by Al. Exposure to Al caused up-regulation (SOD and MDH) or down-regulation (SDH, MDH, and SOD), depending on the cultivar, Al level, and plant tissue. The RB867515 cultivar was the most Al-tolerant, showing no decline of nutrient content in plant tissue, photosynthesis, transpiration, and stomatal conductance after exposure to Al; it exhibited the highest Al content in the roots, and showed important MDH and SOD gene expression in the roots. RB928064 only showed low expression of SOD in roots and leaves, while RB935744 showed important expression of the SOD gene only in the leaves. Sugarcane cultivars were classified in the following descending Al-tolerance order: RB867515 > RB928064 = RB935744. These results may contribute to the obtention of Al-tolerant cultivars that can play their genetic potential in soils of low fertility and with low demand for agricultural inputs; the selection of potential plants for breeding programs; the elucidation of Al detoxification mechanisms employed by sugarcane cultivars.

Bacterial and Archaeal Communities Change With Intensity of Vegetation Coverage in Arenized Soils From the Pampa Biome.

Arenization occurs in regions that present sandy soils with normal rainfall levels. Predatory use of environmental sources, the dissolution of arenitic rocks and reworking of non-consolidated surface sands intensify this degradation scenario. Thus, this work aimed to evaluate the impact of the arenization process in the Brazilian Pampa Biome and how this phenomenon affects the soil microbial and plant communities. For this purpose, three arenized areas in Southern Brazil (Pampa Biome) were selected and, in each one, three sampling points were studied: arenized (ARA), arenized to grassland transition (AGT), and grassland (GRA) areas. In the three sampling points, soils presented low levels of nutrients, organic matter, mud and pH acidic in all regions but, the presence of vegetation coverage in AGT and GRA areas preserved the topsoil structure. Our study related ARA with bacterial families Alcaligenaceae, Pseudomonadaceae, and Xanthomonadaceae. AGT with bacterial families Bacillaceae and Burkholderiaceae, and plant species Melinis repens (Willd.) Zizka and Paspalum stellatum Humb. and Bonpl. ex Flüggé, and GRA with bacterial families Koribacteraceae, Hyphomicrobiaceae, and Chthoniobacteraceae, and plant species Croton subpannosus Müll.Arg. ex Griseb., Piptochaetium montevidense (Spreng.) Parodi and Elyonurus sp. The three studied areas (as well as sampling points) present soils extremely poor in nutrients with sandy texture, and the bacterial and plant composition well known to be resistant to environmental stresses were dominant. The vulnerability of these areas causes a degradation scenario, which is worsened by agricultural activities. However, in general, this phenomenon is a natural process that occurs mainly due to soil characteristics (poor soils) and climatic variations.

Rhizobium hidalgonense sp. nov., a nodule endophytic bacterium of Phaseolus vulgaris in acid soil.

One Gram-negative, aerobic, motile, rod-shaped bacterium, designated as FH14T, was isolated from nodules of Phaseolus vulgaris grown in Hidalgo State of Mexico. Results based upon 16S rRNA gene (≥99.8 % similarities to known species), concatenated sequence (recA, atpD and glnII) analysis of three housekeeping genes (≤93.4 % similarities to known species) and average nucleotide identity (ANI) values of genome sequence (ranged from 87.6 to 90.0 % to related species) indicated the distinct position of strain FH14T within the genus Rhizobium. In analyses of symbiotic genes, only nitrogen fixation gene nifH was amplified that had nucleotide sequence identical to those of the bean-nodulating strains in R. phaseoli and R. vallis, while nodulation gene nodC gene was not amplified. The failure of nodulation to its original host P. vulgaris and other legumes evidenced the loss of its nodulation capability. Strain FH14T contained summed feature 8 (C18:1 ω6c/C18:1 ω7c, 59.96 %), C16:0 (10.6 %) and summed feature 2 (C12:0 aldehyde/unknown 10.928, 10.24 %) as the major components of cellular fatty acids. Failure to utilize alaninamide, and utilizing L-alanine, L-asparagine and γ-amino butyric acid as carbon source, distinguished the strain FH14T from the type strains for the related species. The genome size and DNA G+C content of FH14T were 6.94 Mbp and 60.8 mol %, respectively. Based on those results, a novel specie in Rhizobium, named Rhizobium hidalgonense sp. nov., was proposed, with FH14T (=HAMBI 3636T = LMG 29288T) as the type strain.

Performance de populações de Milho (Zea Mays L.) em terras altas sob cerrado no Centro-sul do estado do Tocantins, Brasil1

In the state of Tocantins, the crop of maize in the high land under "cerrado" has levels of yield variable, whose average does not exceed 2 t/ha. Events of soil, as acidity, low levels of Ca, Mg, and and organic matter, concur to decrease the yields. The development of genetics materials improved fetching to contribute in the overcoming of there limitations. As initial ativity in a program of genetic improvement, the present study it evaluated a whole of 160 maize populations, in seasons 1994/95, 1995/96 and 1998/99, in the cities of Pedro Afonso and Gurupi, in terms of grain weight (GW), plant height (PH), ear height (EH) and days for feminine flowering (FF). For GW, the effects of the populations were significant in whole the evaluations, occurring yields between 1,59 t/ha the 7,46 t/ha. Populations IAPAR 51, EGO 17, CMS 08, CMS 50, COMPOSTO TERRAS BAIXAS, TAIÚBA, TAITINGA, CMS 28, CMS 15, and SIKALQ, had been distinguished in Pedro Afonso; and 9201, CMS 39, BR 105, and CMS 03, in Gurupi, with yields above of the 5 t/ha. The differences in the productive and agronomics performances in Pedro Afonso and Gurupi, together with significant effect of the interactions populations locals, alert for the conduction of the specifics improvement programs for each local.

No estado do Tocantins, o cultivo de milho em "terras altas sob cerrado" apresenta níveis de produtividade variáveis, cuja média não ultrapassa 2 t/ha. Fatores de solo, como acidez, baixos teores de Ca, Mg, e e matéria orgânica, concorrem para reduzir as produtividades. O desenvolvimento de materiais genéticos melhorados busca contribuir na superação dessas limitações. Como atividade inicial em um programa de melhoramento genético, o presente estudo avaliou um total de 160 populações de milho, nas safras 1994/95, 1995/96 e 1998/99, nos municípios de Pedro Afonso e Gurupi, em termos de produtividade de grãos (PG), altura da planta (AP), altura da espiga (AE) e dias para florescimento feminino (FF). Para PG, os efeitos de populações foram significativos em todas as avaliações, ocorrendo produtividades entre 1,59 t/ ha a 7,46 t/ha. Destacaram-se as populações IAPAR 51, EGO 17, CMS 08, CMS 50, COMPOSTO TERRAS BAIXAS, TAIÚBA, TAITINGA, CMS 28, CMS 15 e SIKALQ, em Pedro Afonso, e K9201, CMS 39, BR 105 e CMS 03, em Gurupi, com produtividades acima de 5 t/ha. As diferenças nas performances produtivas e agronômicas em Pedro Afonso e Gurupi, juntamente com efeitos significativos das interações populações locais, alertam para a condução de programas de melhoramento específicos para cada local.

Performance de populações de Milho (Zea Mays L.) em terras altas sob cerrado no Centro-sul do estado do Tocantins, Brasil1

In the state of Tocantins, the crop of maize in the high land under "cerrado" has levels of yield variable, whose average does not exceed 2 t/ha. Events of soil, as acidity, low levels of Ca, Mg, and and organic matter, concur to decrease the yields. The development of genetics materials improved fetching to contribute in the overcoming of there limitations. As initial ativity in a program of genetic improvement, the present study it evaluated a whole of 160 maize populations, in seasons 1994/95, 1995/96 and 1998/99, in the cities of Pedro Afonso and Gurupi, in terms of grain weight (GW), plant height (PH), ear height (EH) and days for feminine flowering (FF). For GW, the effects of the populations were significant in whole the evaluations, occurring yields between 1,59 t/ha the 7,46 t/ha. Populations IAPAR 51, EGO 17, CMS 08, CMS 50, COMPOSTO TERRAS BAIXAS, TAIÚBA, TAITINGA, CMS 28, CMS 15, and SIKALQ, had been distinguished in Pedro Afonso; and 9201, CMS 39, BR 105, and CMS 03, in Gurupi, with yields above of the 5 t/ha. The differences in the productive and agronomics performances in Pedro Afonso and Gurupi, together with significant effect of the interactions populations locals, alert for the conduction of the specifics improvement programs for each local.

No estado do Tocantins, o cultivo de milho em "terras altas sob cerrado" apresenta níveis de produtividade variáveis, cuja média não ultrapassa 2 t/ha. Fatores de solo, como acidez, baixos teores de Ca, Mg, e e matéria orgânica, concorrem para reduzir as produtividades. O desenvolvimento de materiais genéticos melhorados busca contribuir na superação dessas limitações. Como atividade inicial em um programa de melhoramento genético, o presente estudo avaliou um total de 160 populações de milho, nas safras 1994/95, 1995/96 e 1998/99, nos municípios de Pedro Afonso e Gurupi, em termos de produtividade de grãos (PG), altura da planta (AP), altura da espiga (AE) e dias para florescimento feminino (FF). Para PG, os efeitos de populações foram significativos em todas as avaliações, ocorrendo produtividades entre 1,59 t/ ha a 7,46 t/ha. Destacaram-se as populações IAPAR 51, EGO 17, CMS 08, CMS 50, COMPOSTO TERRAS BAIXAS, TAIÚBA, TAITINGA, CMS 28, CMS 15 e SIKALQ, em Pedro Afonso, e K9201, CMS 39, BR 105 e CMS 03, em Gurupi, com produtividades acima de 5 t/ha. As diferenças nas performances produtivas e agronômicas em Pedro Afonso e Gurupi, juntamente com efeitos significativos das interações populações locais, alertam para a condução de programas de melhoramento específicos para cada local.

Partial diallel cross between exotic and adapted maize populations evaluated in acid soil A NAME="top"> /A>

In Brazil, acid soils represent a large portion of the agricultural area and the development of cultivars with tolerance to acidity has shown to be feasible. The identification of germoplasm potentially tolerant to acidity was the purpose of this work. Two distinct groups of maize (Zea mays L.) populations were crossed according to the partial diallel mating scheme: Group [1] with six adapted populations and Group [2] with seven exotic varieties. All varieties and crosses were evaluated under the condition of acid and low fertility soil. Traits analyzed were: EY- ear yield, PH- plant height and EH- ear height. Outstanding varieties per se, with yield higher than 3 t ha-1, were SUWAN-2, TAITINGA, TAIÚBA and IUBATÃ in Group [1]; and CUPURICO DMR, TUXPEÑO AMARILLO, and AMARILLO DENTADO in Group [2]. Heterosis and its components showed no significant variation for PH and EH; and only average heterosis was significant for EY. The general combining ability effects (g i and g j) showed significant variation (P 0.01) for all traits and were due mainly to the variation of variety effects. The higher estimates g i for EY were exhibited by WP 12 (0.178 t ha-1), TAIÚBA (0.176) and TAITINGA (0.161) in Group [1]; and for g j by CUPURICO DMR (0.300), TAITINGA TUXPEÑO AMARILLO (0.280) in Group [2], respectively. The variety cross TAITINGA x TUXPEÑO AMARILLO with mean yield of 4.34 t ha-1 and 25% of mid-parent heterosis may be indicated as an heterotic pattern. PH and EH were not considered as limiting to preclude the use of the outstanding populations. The varieties SUWAN 2, CUPURICO DMR, and TAITINGA were suggested to be used in maize breeding programs for acid soils.

No Brasil os solos ácidos representam uma grande parte da área agricultável e o desenvolvimento de cultivares com tolerância à acidez tem-se mostrado exequível. A identificação de germoplasma potencialmente tolerante à acidez foi o propósito deste trabalho. Dois grupos distintos de populações de milho (Zea mays L.) foram cruzados segundo o esquema de dialelo parcial: Grupo [1] com seis populações adaptadas e Grupo [2] com sete exóticas. As populações e seus híbridos foram avaliados sob condição de solo ácido e de baixa fertilidade. Os caracteres analisados foram: EY- peso de espigas, PH- altura da planta e EH- altura da espiga. As populações que sobressaíram, com produtividade per se acima de 3 t ha-1 foram SUWAN-2, TAITINGA, TAIÚBA e IUBATÃ no Grupo [1]; e CUPURICO DMR, TUXPEÑO AMARILLO, e AMARILLO DENTADO no Grupo [2]. A heterose e seus componentes mostraram variação não significativa para PH e EH; e somente a heterose média foi significativa para EY. Os efeitos de capacidade geral de combinação (g i e g j) mostraram variação significativa (P 0,01) para todos os caracteres e foram devidos principalmente à variação dos efeitos de variedades. As maiores estimativas de g i no Grupo [1] para EY (t ha-1) foram exibidas por WP 12 (0,178 t ha-1), TAIÚBA (0,176) and TAITINGA (0.161) no Grupo [1]; e para g j por CUPURICO DMR (0.300), TAITINGA TUXPEÑO AMARILLO (0.280) no Grupo [2], respectivamente. O híbrido interpopulacional TAITINGA x TUXPEÑO AMARILLO com produção média de 4,34 t ha-1 e 25% de heterose pode ser indicado como um padrão heterótico. A altura da planta e da espiga não foram consideradas limitantes para impedir o uso das populações mais promissoras. As variedades SUWAN 2, CUPURICO DMR e TAITINGA foram as mais promissoras para programas de mehoramento visando adaptação às condições de solo ácidos.

Saturação por bases e híbridos de milho sob sistema plantio direto A NAME="top"> /A>

The knowledge of the hybrids of suitable maize to each condicion of the ground in under no-tillage is of significant importance technique. To evaluate the response of corn hybrids to base saturation levels (V%), two experiments were performed with V% equal to 45 and 65, in cerrado areas of Uberaba, MG, Brazil, four years under no-tillage. A completely randomized block design was used, with four replications. Seven corn hybrids represent the treatments: Z 8474, BR3123, AG 122, C 333, D 657, Exceller and P 3071. The results showed that the base saturation of 65% contributed more for the increments in yield components and for the grain yield than the 45% base saturation level. The hybrids presented different yield responses, the highest beeing for the 65% base saturation treatment: P 3071 and Z 8474 and 2); for the 45% base saturation treatment: C 333. Choosing the right hybrids for each base saturation level is an important criterium to maximize corn yields under no-tillage in the cerrado region of Brazil.

O conhecimento dos híbridos adaptados a cada condição de reação do solo em sistema plantio direto é de significativa importância técnica. Para avaliar o comportamento de híbridos de milho sob sistema plantio direto, quanto a alguns componentes de rendimento, submetidos a níveis de saturação por bases, foram conduzidos dois experimentos no V% 45 e V% 65 em área com 4 anos em sistema plantio direto, na região dos cerrados, em Uberaba, MG. Os experimentos foram desenvolvidos no delineamento em blocos ao acaso, com quatro repetições. Os sete tratamentos foram constituídos pelos seguintes híbridos de milho: Z 8474, BR 3123, AG 122, C 333, D 657, Exceller e P 3071. Na média dos híbridos de milho estudados a saturação por bases de 65% foi a que mais contribuiu para os incrementos nos componentes do rendimento e nos rendimentos de grãos. Os híbridos apresentaram comportamento diferenciado no rendimento de grãos, destacando-se na saturação por bases 65%, os híbridos P 3071 e o Z 8474 e no nível 45% destacou-se o híbrido C 333. A utilização de híbridos específicos para cada nível de saturação por bases mostrou-se uma importante ferramenta para a maximização do rendimento da cultura do milho em sistema plantio direto no cerrado.

Saturação por bases e híbridos de milho sob sistema plantio direto A NAME="top"> /A>

The knowledge of the hybrids of suitable maize to each condicion of the ground in under no-tillage is of significant importance technique. To evaluate the response of corn hybrids to base saturation levels (V%), two experiments were performed with V% equal to 45 and 65, in cerrado areas of Uberaba, MG, Brazil, four years under no-tillage. A completely randomized block design was used, with four replications. Seven corn hybrids represent the treatments: Z 8474, BR3123, AG 122, C 333, D 657, Exceller and P 3071. The results showed that the base saturation of 65% contributed more for the increments in yield components and for the grain yield than the 45% base saturation level. The hybrids presented different yield responses, the highest beeing for the 65% base saturation treatment: P 3071 and Z 8474 and 2); for the 45% base saturation treatment: C 333. Choosing the right hybrids for each base saturation level is an important criterium to maximize corn yields under no-tillage in the cerrado region of Brazil.

O conhecimento dos híbridos adaptados a cada condição de reação do solo em sistema plantio direto é de significativa importância técnica. Para avaliar o comportamento de híbridos de milho sob sistema plantio direto, quanto a alguns componentes de rendimento, submetidos a níveis de saturação por bases, foram conduzidos dois experimentos no V% 45 e V% 65 em área com 4 anos em sistema plantio direto, na região dos cerrados, em Uberaba, MG. Os experimentos foram desenvolvidos no delineamento em blocos ao acaso, com quatro repetições. Os sete tratamentos foram constituídos pelos seguintes híbridos de milho: Z 8474, BR 3123, AG 122, C 333, D 657, Exceller e P 3071. Na média dos híbridos de milho estudados a saturação por bases de 65% foi a que mais contribuiu para os incrementos nos componentes do rendimento e nos rendimentos de grãos. Os híbridos apresentaram comportamento diferenciado no rendimento de grãos, destacando-se na saturação por bases 65%, os híbridos P 3071 e o Z 8474 e no nível 45% destacou-se o híbrido C 333. A utilização de híbridos específicos para cada nível de saturação por bases mostrou-se uma importante ferramenta para a maximização do rendimento da cultura do milho em sistema plantio direto no cerrado.

Partial diallel cross between exotic and adapted maize populations evaluated in acid soil A NAME="top"> /A>

In Brazil, acid soils represent a large portion of the agricultural area and the development of cultivars with tolerance to acidity has shown to be feasible. The identification of germoplasm potentially tolerant to acidity was the purpose of this work. Two distinct groups of maize (Zea mays L.) populations were crossed according to the partial diallel mating scheme: Group [1] with six adapted populations and Group [2] with seven exotic varieties. All varieties and crosses were evaluated under the condition of acid and low fertility soil. Traits analyzed were: EY- ear yield, PH- plant height and EH- ear height. Outstanding varieties per se, with yield higher than 3 t ha-1, were SUWAN-2, TAITINGA, TAIÚBA and IUBATÃ in Group [1]; and CUPURICO DMR, TUXPEÑO AMARILLO, and AMARILLO DENTADO in Group [2]. Heterosis and its components showed no significant variation for PH and EH; and only average heterosis was significant for EY. The general combining ability effects (g i and g j) showed significant variation (P 0.01) for all traits and were due mainly to the variation of variety effects. The higher estimates g i for EY were exhibited by WP 12 (0.178 t ha-1), TAIÚBA (0.176) and TAITINGA (0.161) in Group [1]; and for g j by CUPURICO DMR (0.300), TAITINGA TUXPEÑO AMARILLO (0.280) in Group [2], respectively. The variety cross TAITINGA x TUXPEÑO AMARILLO with mean yield of 4.34 t ha-1 and 25% of mid-parent heterosis may be indicated as an heterotic pattern. PH and EH were not considered as limiting to preclude the use of the outstanding populations. The varieties SUWAN 2, CUPURICO DMR, and TAITINGA were suggested to be used in maize breeding programs for acid soils.

No Brasil os solos ácidos representam uma grande parte da área agricultável e o desenvolvimento de cultivares com tolerância à acidez tem-se mostrado exequível. A identificação de germoplasma potencialmente tolerante à acidez foi o propósito deste trabalho. Dois grupos distintos de populações de milho (Zea mays L.) foram cruzados segundo o esquema de dialelo parcial: Grupo [1] com seis populações adaptadas e Grupo [2] com sete exóticas. As populações e seus híbridos foram avaliados sob condição de solo ácido e de baixa fertilidade. Os caracteres analisados foram: EY- peso de espigas, PH- altura da planta e EH- altura da espiga. As populações que sobressaíram, com produtividade per se acima de 3 t ha-1 foram SUWAN-2, TAITINGA, TAIÚBA e IUBATÃ no Grupo [1]; e CUPURICO DMR, TUXPEÑO AMARILLO, e AMARILLO DENTADO no Grupo [2]. A heterose e seus componentes mostraram variação não significativa para PH e EH; e somente a heterose média foi significativa para EY. Os efeitos de capacidade geral de combinação (g i e g j) mostraram variação significativa (P 0,01) para todos os caracteres e foram devidos principalmente à variação dos efeitos de variedades. As maiores estimativas de g i no Grupo [1] para EY (t ha-1) foram exibidas por WP 12 (0,178 t ha-1), TAIÚBA (0,176) and TAITINGA (0.161) no Grupo [1]; e para g j por CUPURICO DMR (0.300), TAITINGA TUXPEÑO AMARILLO (0.280) no Grupo [2], respectivamente. O híbrido interpopulacional TAITINGA x TUXPEÑO AMARILLO com produção média de 4,34 t ha-1 e 25% de heterose pode ser indicado como um padrão heterótico. A altura da planta e da espiga não foram consideradas limitantes para impedir o uso das populações mais promissoras. As variedades SUWAN 2, CUPURICO DMR e TAITINGA foram as mais promissoras para programas de mehoramento visando adaptação às condições de solo ácidos.

Escória de siderurgia e calcário na correção da acidez do solo cultivado com cana-de-açúcar em vaso

The neutralizing components of steel will residue are linked with high energy, combined with the presence of several metallic elements; these characteristics interfere in the chemical evaluation of their neutralization power. The aim of this study was to evaluate if the neutralization power of lime would be compatible with the residue used to produce steel, as a function of pH, H+Al, and Ca+Mg contents on acid soils in the Cerrado region, for sugar cane cultivation. This study was performed in 20 dm³ pots in a greenhouse, with Acrustox and Quartzipsamment soils, in two sucessive cultivations of sugar cane (first cutting and second cutting), harvest was 210 days after ammendments incorporation, for each cultivation. Treatments constituted of two corrective agents: limestone and steel will residue, in two levels of application, as follows: level 1 = the rate to increase V to 50%, and level 2 = double of the rate necessary to increase V to 50%. At the end of each cultivation, soils were sampled and analysed chemicaly. The reactivity of the steel will residue depends on the soil class type. The efficiency of the steel will residue based on the power of neutralization adopted for limestone was not sufficient to allow evaluation of the quantity necessary of the product for the correction of soil acidity, suggesting the necessity of further studies.

A avaliação química da escória de siderurgia, como corretivo de acidez do solo, pode sofrer interferências em razão da presença da alta energia de ligação dos seus constituintes neutralizantes e a presença de diversos elementos metálicos. Tendo como objetivo avaliar se a recomendação de correção baseada no poder de neutralização adotado para o calcário é compatível para escória de siderurgia, em função das alterações do valor pH, teores de H+Al, Ca+Mg em solos ácidos da região dos cerrados cultivados com cana-de-açúcar, realizou-se o presente experimento, em condições de casa de vegetação, em vaso com 20 dm³ do Latossolo Vermelho e do Neossolo Quartzarênico em dois cultivos sucessivos da cana-de-açúcar (cana-planta e cana-soca) por 210 dias após a incorporação dos corretivos, a cada cultivo. Os tratamentos, foram constituídos de dois corretivos calcário e escória em dois níveis de aplicação, como segue: nível 1= a dose para elevar V=50% e nível 2= dobro da dose necessária para elevar V=50%. Ao término de cada cultivo, os solos foram amostrados e analisados quimicamente. A reatividade da escória de siderurgia depende da classe de solo. A eficiência da escória de siderurgia baseado no poder de neutralização adotado para o calcário não apresentou comportamento satisfatório para estimar a necessidade de produto para a correção da acidez do solo, sugerindo a necessidade de mais estudos.

Escória de siderurgia e calcário na correção da acidez do solo cultivado com cana-de-açúcar em vaso

The neutralizing components of steel will residue are linked with high energy, combined with the presence of several metallic elements; these characteristics interfere in the chemical evaluation of their neutralization power. The aim of this study was to evaluate if the neutralization power of lime would be compatible with the residue used to produce steel, as a function of pH, H+Al, and Ca+Mg contents on acid soils in the Cerrado region, for sugar cane cultivation. This study was performed in 20 dm³ pots in a greenhouse, with Acrustox and Quartzipsamment soils, in two sucessive cultivations of sugar cane (first cutting and second cutting), harvest was 210 days after ammendments incorporation, for each cultivation. Treatments constituted of two corrective agents: limestone and steel will residue, in two levels of application, as follows: level 1 = the rate to increase V to 50%, and level 2 = double of the rate necessary to increase V to 50%. At the end of each cultivation, soils were sampled and analysed chemicaly. The reactivity of the steel will residue depends on the soil class type. The efficiency of the steel will residue based on the power of neutralization adopted for limestone was not sufficient to allow evaluation of the quantity necessary of the product for the correction of soil acidity, suggesting the necessity of further studies.

A avaliação química da escória de siderurgia, como corretivo de acidez do solo, pode sofrer interferências em razão da presença da alta energia de ligação dos seus constituintes neutralizantes e a presença de diversos elementos metálicos. Tendo como objetivo avaliar se a recomendação de correção baseada no poder de neutralização adotado para o calcário é compatível para escória de siderurgia, em função das alterações do valor pH, teores de H+Al, Ca+Mg em solos ácidos da região dos cerrados cultivados com cana-de-açúcar, realizou-se o presente experimento, em condições de casa de vegetação, em vaso com 20 dm³ do Latossolo Vermelho e do Neossolo Quartzarênico em dois cultivos sucessivos da cana-de-açúcar (cana-planta e cana-soca) por 210 dias após a incorporação dos corretivos, a cada cultivo. Os tratamentos, foram constituídos de dois corretivos calcário e escória em dois níveis de aplicação, como segue: nível 1= a dose para elevar V=50% e nível 2= dobro da dose necessária para elevar V=50%. Ao término de cada cultivo, os solos foram amostrados e analisados quimicamente. A reatividade da escória de siderurgia depende da classe de solo. A eficiência da escória de siderurgia baseado no poder de neutralização adotado para o calcário não apresentou comportamento satisfatório para estimar a necessidade de produto para a correção da acidez do solo, sugerindo a necessidade de mais estudos.