Djail Santos

Produtividade e morfologia de vagens e sementes de variedades de fava no Estado da Paraíba

O objetivo deste trabalho foi avaliar a produtividade da fava (Phaseolus lunatus L.) e descrever a morfologia de suas vagens e sementes. Oito variedades de fava (Amarela-cearense, Boca-de-moca, Branquinha, Mororo, Olho-de-ovelha, Olho-de-peixe, Orelha-de-vo, Raio-de-sol) foram avaliadas em experimento de campo no periodo de julho a dezembro de 1999, em Bananeiras, PB. Todas as variedades apresentaram habito de crescimento indeterminado trepador e vagens compridas, de forma oblonga e recurvada, com numero de sementes variando de duas a quatro. A variedade com vagens de maior comprimento (89,9 mm) e maior peso de 100 sementes (79,5 g) foi a Orelha-de-vo. As variedades Olho-de-ovelha e Orelha-de-vo apresentaram a maior e menor produtividade media de 0,852 e 0,293 t ha-1 de sementes, respectivamente. Com base na variacao do numero de dias para florescimento e colheita, as variedades foram classificadas em precoce (Amarela-cearense, Olho-de-peixe e Orelha-de-vo), intermediaria (Boca-de-moca, Branquinha, Mororo e Olho-de-ovelha) e tardia (Raio-de-sol). As variedades Olho-de-ovelha, Branquinha, Boca-de-moca, Amarela-cearense, Mororo e Olho-de-peixe sao as mais promissoras para cultivos de sequeiro, com irrigacao suplementar.

Fósforo em solos representativos do estado da paraíba: I- isotermas de adsorção e medidas do fator capacidade de fósforo

O conhecimento do fator capacidade de P (FCP) dos solos do Estado da Paraiba e importante para tornar mais eficiente a interpretacao do teor de P disponivel e a recomendacao de adubacao fosfatada em solos desse Estado. Os objetivos deste trabalho foram avaliar os parâmetros das isotermas de adsorcao de P (Langmuir e Freundlich), por meio das tecnicas de regressao nao linear e de linearizacao, em amostras de solos do Estado da Paraiba, e verificar a correlacao dos valores desses parâmetros com caracteristicas quimicas e fisicas desses solos. Foram coletadas amostras de doze solos na camada de 0-30 cm de profundidade, sendo seis solos mais intemperizados e seis menos intemperizados, de modo a ter ampla variacao de valores de caracteristicas fisicas e quimicas de cada grupo de solos. O modelo hiperbolico da isoterma de Langmuir foi ajustado por meio da tecnica de regressao nao linear (regiao unica) e por meio da tecnica de linearizacao (regiao unica e segunda regiao). Foram realizadas analises de correlacao entre os valores dos parâmetros das isotermas e caracteristicas do solo que refletem o FCP. Em todos os solos, o modelo ajustado por meio da tecnica de regressao nao linear apresentou melhor ajuste aos dados observados, em comparacao ao mesmo modelo ajustado por meio da tecnica de linearizacao. No grupo de solos mais intemperizados, os valores de capacidade maxima de adsorcao de fosfato (CMAP) apresentaram correlacao elevada com os valores de P remanescente (r = -0,95**), teor de oxihidroxidos de Fe (r = 0,90**) e equivalente de umidade (r = 0,88**), mas nao se correlacionaram com o teor de argila (r = 0,64ns). Dentro do grupo de solos menos intemperizados, os valores de CMAP correlacionaram-se com os valores de P remanescente (r = -0,99**), equivalente de umidade (r = 0,93**) e teor de argila (r = 0,97**), mas nao se correlacionaram com o teor de oxi-hidroxidos de Fe livre (r = 0,10ns).

Indicadores biológicos de qualidade do solo em diferentes sistemas de uso no brejo paraibano

A avaliacao da qualidade do solo e uma ferramenta importante para monitorar a sua degradacao, bem como planejar a implantacao de praticas sustentaveis de manejo. Neste trabalho, objetivou-se avaliar indicadores biologicos de qualidade do solo em um Latossolo Amarelo distrofico, submetido a diferentes sistemas de uso em Areia-PB. Foram utilizadas amostras de solo coletadas na camada aravel (0-20 cm) em areas de mata nativa, fruticultura, cana-de-acucar, sucessao de cultivos, pastagem e consorcio de culturas. Foram avaliados o carbono orgânico total (COT), carbono da biomassa microbiana (CBM), quociente microbiano (qMic), respiracao basal (RB) e quociente metabolico (qCO2). Os resultados obtidos indicaram que as areas sob gramineas apresentaram uma tendencia de manutencao do COT e menores reducoes no CBM, entretanto, apresentaram elevados valores de qCO2, indicando a ocorrencia de um processo degradativo. A area sob fruticultura apresentou leves reducoes no COT e CBM e baixos valores de qCO2, indicando que esse sistema pode estar se ajustando a um novo estado de equilibrio. As areas sob sucessao de cultivos e consorcio de culturas apresentaram as maiores reducoes no COT e CBM e elevados valores de qCO2, demonstrando um elevado estagio de degradacao desses sistemas. Pode-se concluir que todos os sistemas agricolas estudados promoveram perda de qualidade do solo, sendo esse fato mais pronunciado nas areas sob manejo mais intensivo. O CBM e qCO2 mostraram-se bastantes sensiveis as alteracoes decorrentes do uso agricola do solo, apresentando grande potencial para estudos de sua qualidade.

Absorção e distribuição de chumbo em plantas devetiver, jureminha e algaroba

SUMMARY : ABSORPTION AND DISTRIBUTION OF LEAD IN VETIVER,MIMOSA AND MESQUITE PLANTS The use of plants for phytoremediation of metal-contaminated areas is an emergingtechnology, and studies concerning heavy metal tolerance, absorption and distribution inplants are essential for the success of such programs. This study was carried out to evaluatethe tolerance, absorption and distribution of lead (Pb) in vetiver grass [ Vetiveria zizanioides(L.) Nash], mimosa [ Desmanthus virgatus (L.) Willd] and mesquite trees [ Prosopis juliflora(SW) DC] subjected to increasing lead doses in solution. The experiment was conductedunder a screenhouse, at the DSER/CCA/UFPB, Areia-PB, Brazil. The species were grownin nutrient solution containing increasing Pb levels (0, 50, 100 and 200 mg L -1 ) during a 45-day exposure period. An entirely randomized split-plot design was used with threereplicates. The main plot was represented by the plant species and the subplot by Pblevels. The increased Pb levels caused significant reductions of dry mass of the root, shootand whole plant (root + shoot) in the three species under study. Based on critical toxicitylevels, the tolerance of vetiver to Pb contamination was higher than in the other species. Invetiver and mesquite plants, the roots were the component most sensitive to Pbcontamination, whereas a similar response to Pb by all plant components was observed formimosa. Total Pb concentrations and content in plant compartments were significantlyaffected by the increasing Pb levels in solution, and a higher accumulation of this elementwas observed in the roots of the three species under study. The highest Pb concentrationand content were found in all compartments of vetiver, which suggests a high potential ofthis grass for phytoremediation of Pb-contaminated areas.Index terms: pollution, heavy metal, phytotoxicity, tolerance, phytoremediation.

Decomposição e liberação de N, P e K de esterco bovino e de cama de frango isolados ou misturados

The use of organic residues in the crop fertilizations demand information about the dynamics of decomposition and release of nutrients contained therein. This study aimed to evaluate the decomposition and release of N, P and K from organic residues cattle manure and poultry litter isolates or mixed, using the method of decomposition bags (litterbag) in Alfissol of Coast Tableland in Paraiba State. The experiment was conducted in randomized block with treatments arranged in a factorial 3 × 2 × 5 refers to three organic residues [(cattle manure (CM), poultry litter (PL) and the mixture of these residues in the ratio of 1: 1, called mixed manure (MM)], the incorporation of two layers (0-10 and 10-20 cm) and six evaluation periods (0, 30, 90, 150, 210 and 270 days after application) and three replications. From the results it was observed that the depth did not affect the decomposition of organic residues CM and MM and that it was more rapid in PL (0.0035 g day-1), more slow in CM (0.0010 g day-1 ) and occurred at a speed intermediate in MM (0.0020 g day-1). It was release more faster of N in MM (0.0011 g day-1), of P in CM (0.0040 g day-1) and K on PL (0.0025 g day-1), with an upward trend in the release of N in the PL and P in all residues with the incorporation at 10-20 cm. After 270 daa, it was estimated that the release of nutrients in the residues CM, PL and MM in relation to the initial content was 5.0, 15.0 and 28.0% for N; 80.0, 68.0 and 47.0% for P; and 20.0, 53.0 and 32.0% for K. In absolute terms, these percentages represented, respectively, 19.0, 103.0 and 149.5 kg ha-1 N, 28.0, 18.0 and 15.0 kg ha-1 P, and 75.0, 493.0 and 209.0 kg ha-1 K. The organic residues proved inadequate to meet the demand alone nutritional short cycle crops in these soils.

Fósforo em solos representativos do estado da paraíba: II- disponibilidade de fósforo para plantas de milho

Os laboratorios de fertilidade do solo do Estado da Paraiba utilizam apenas o extrator Mehlich-1 para avaliar o teor de P disponivel, independente do grau de intemperismo do solo. Como os solos pouco intemperizados representam a maioria dos solos do Estado, e necessario avaliar a eficiencia do Mehlich-1 e de outros extratores usados para avaliacao da disponibilidade de P para as plantas. O objetivo deste trabalho foi avaliar a eficiencia dos extratores Mehlich-1 (M-1), Mehlich-3 (M-3), Bray-1 (B-1) e resina de troca ionica mista (RTI) na quantificacao do P disponivel para plantas de milho em solos do Estado da Paraiba. Amostras de 12 solos representativos do Estado da Paraiba foram coletadas na camada de 0-30 cm de profundidade, sendo seis solos mais intemperizados e seis solos menos intemperizados, com ampla variacao de caracteristicas fisicas e quimicas. Para os solos PA, PVe, LA, RL, TX, SX e RY, aplicaram-se as doses 0; 43,75; 87,5; 175 e 350 mg dm-3 de P. Para os solos PAC e RR, aplicaram-se as doses 0; 37,5; 75; 150 e 300 mg dm-3 de P. Para os solos PVA, PVd e VX, as doses de P foram 0; 51,25; 102,5; 205 e 410 mg dm-3 de P. O experimento foi conduzido em casa de vegetacao e as doses de P aplicadas foram homogeneizadas em 100 % do volume de solo de cada vaso (3 dm3). Foi cultivado milho por um periodo de 35 dias e foram determinados os niveis criticos de P no solo pelos extratores e o nivel critico de P na planta. Independente da dose de P aplicada, o extrator M-3 foi o que extraiu mais P dos solos e o B-1 o que extraiu menos. Quando se aplicaram pequenas doses de P aos solos, o M-1 e a RTI extrairam quantidades semelhantes de P, mas, nas maiores doses, a RTI extraiu mais P que o M-1. Ao contrario do que foi verificado para a planta e para a RTI, para os extratores M-1, M-3 e B-1 a taxa de recuperacao do P aplicado ao solo correlacionou-se com o fator capacidade de fosforo (FCP). Por outro lado, os niveis criticos de P no solo pelos extratores M-1, M-3 e B-1 e os niveis criticos de P na planta nao se correlacionaram com caracteristicas do solo relacionadas com o FCP, diferentemente do que foi verificado para os niveis criticos de P no solo pela RTI. Em casa de vegetacao, qualquer um dos extratores avaliados mostrou-se eficiente para avaliacao da disponibilidade de P para plantas de milho em solos representativos do Estado da Paraiba, uma vez que o P extraido por esses extratores apresentou boa correlacao com o P acumulado na planta.

One-Shot Time Management Analysis in EPOS

One of the tasks of an operating system is to handle time events. Traditionally, time management is based on periodic interrupts from one of the systems hardware timers (ticks). However, this approach has some limitations, as lack of precision, large overhead, and large power consumption. These limitations have motivated the use of non-periodic timers (e.g. one-shot timers), specially in specific-purpose operating systems with timing restrictions, such as embedded, real-time, and multimedia systems. This work presents a comparison between one-shot and periodic time implementations in the time management abstractions in EPOS (embedded parallel operating system). We compare both implementations in terms of memory footprint, number of context switches, number of interrupt handler executions and run time in different execution scenarios.

Agronomic Evaluation of Legume Cover Crops for Sustainable Agriculture

The agronomic characteristics of different legume cover crops and their effects on soil chemical properties were investigated in a short-term field study. We compared weed biomass, nitrogen equivalence, growth rate, leaf chlorophyll content, cover crop biomass, soil total organic carbon, and soil total nitrogen under eight different legume cover crops in a short-term field experiment. We found the highest growth rate, cover crop dry biomass, N plant content, and N contribution with C. ochroleuca plants, whereas for leaf chlorophyll content, soil organic carbon, and total nitrogen the highest values were found with M. pruriens. We did not find any significant difference among C. ochroleuca and M. pruriens for cover crop dry biomass. Our findings suggest that the incorporation of cover crops into the soil can change positively the soil chemical properties, such as soil organic carbon and total nitrogen. Our results also highlight the importance of considering the short-term effect of cover crops on the tropical soil fertility maintenance, in this case, Regosol.

TROCAS GASOSAS E EFICIÊNCIA FOTOQUÍMICA DE GENÓTIPOS DE FAVA CULTIVADOS EM SOLO COMPACTADO

The effects of soil compaction on crop growth an d productivity have been well studied in recent years, however, studies on the physiological respon es of crops to compaction are scarce. The objectiv e of this study was to evaluate the effect of soil compaction on gas exchange, and photochemical efficiency of l ima bean (Phaseolus lunatus L.) genotypes of different growth habits. The expe rim ntal design was a randomized block in a 3×4 factorial arrangement, with three lima bea n genotypes (Branca-Pequena, Orelha-de-Vó and Roxin ha) and four compaction levels (soil densities of 1.1, .3, 1.5 and 1.7 g cm ), with four replications. The following variables were evaluated at 38 days after sowing: p hotosynthetic rate ( A), leaf transpiration ( E), stomatal conductance (g s), internal CO2 concentration (Ci), instantaneous water use effici n y (WUE), intrinsic water use efficiency (iWUE), instantaneous carboxylation efficiency (iCE) and photochemical efficiency ( Fo, Fm, Fv and Fv/Fm). The data were subjected to analysis of variance at 5% probability by the F test. The genotypes showed a reduction in the photosynthetic rate with increasing soil compaction. The soil compaction aff ected the photochemical efficiency of the genotype Orelha-deVó, with the Fm and Fv fitting to the linear model, and the Fv/Fm fitting to the quadratic model . The genotype Orelha-de-Vó had the highest rate of E and gs at the soil densities of 1.24 and 1.29 g cm , respectively. Regarding the photosynthetic rate, th genotype Roxinha is more efficient than Branca-Pequena at the soil dens ity of 1.7 g cm .

MAPPING OF PEDOLOGICAL POTENTIAL OF SOILS FOR CULTIVATION OF THE SUGAR CANE (Saccharum spp) IN PARAÍBA STATE USING GEOTECHNOLOGIES

Agricultural planning, as a precept of environmental policy, is an instrument of great importance in the process of managing the rural space and agricultural activity. This work aimed to identify and map the soil information of the lands of the State of Paraiba for the sugar cane cultivation, aiming to recognize the potential of the physical environment. In the methodology, the Agricultural Zoning of the State of Paraiba and the digital map of soils were used in a data base elaborated in the software SPRING 5.2.2, extracted the pedological information of the soils and elaborated the pedological potential. The results showed that with the use of geoprocessing techniques it was possible the spatialization of the areas and the definition of the favorable environments of potential of the culture contributing to the reduction of the risks of degradation of the environment; The State of Paraiba presents a greater pedological potential for the cultivation of sugarcane in 10.04% of its total area; The areas identified as Very Low Potential correspond to 54.52% of the total area distributed throughout the State; The Argisols present the smallest and the Neosols the greatest impediments to the development of the culture; It was not possible to map smaller areas due to the scale of work, with the possibility of cultivating the sugar cane cultivation in small areas not identified in this study.