Rosa Toyoko Shiraishi Frighetto

Discrimination of management effects on soil parameters by using principal component analysis: a multivariate analysis case study

One of the major interests in soil analysis is the integrated evaluation of soil properties, which might be indicators of soil quality. Unsupervised methods of multivariate statistics are powerful tools for this integrated assessment and can help soil researchers to extract much more information from their data. A multivariate study was carried out in three farms from Guaira, State of Sao Paulo, Brazil. Conventionally managed plots that intensively utilized pesticides and chemical fertilizers were compared with both non-disturbed forest areas and alternatively managed plots. The latter were under ecological farming employing effective microorganisms (EM) integrated with crop residues. Eight soil parameters were determined for each plot. Hierarchical cluster analysis (HCA) was used to verify the similarity among the plots. The multivariate approach of principal component analysis (PCA) allowed us to distinguish the areas as a function of the soil management and determine which are the most important parameters to characterize them. The forest areas presented higher microbial biomass with lower cellulolytics population than at cultivated sites. The alternative plots were characterized by higher microbial biomass and polysaccharide content with lower phosphate solubilizers and cellulolytics microorganisms colony counts than at the conventional areas. The higher observed levels of microbial biomass and polysaccharide content in the alternative areas can be attributed to the effects of the alternative soil amendment. All these effects can be clearer globally visualized with the aid of PCA, through the biplots.

Avaliação do Uso de Métodos Quimiométricos em Análise de Solos

One of the major interests in soil analysis is the evaluation of its chemical, physical and biological parameters, which are indicators of soil quality (the most important is the organic matter). Besides there is a great interest in the study of humic substances and on the assessment of pollutants, such as pesticides and heavy metals, in soils. Chemometrics is a powerful tool to deal with these problems and can help soil researchers to extract much more information from their data. In spite of this, the presence of these kinds of strategies in the literature has obtained projection only recently. The utilization of chemometric methods in soil analysis is evaluated in this article. The applications will be divided in four parts (with emphasis in the first two): (i) descriptive and exploratory methods based on Principal Component Analysis (PCA); (ii) multivariate calibration methods (MLR, PCR and PLS); (iii) methods such as Evolving Factor Analysis and SIMPLISMA; and (iv) artificial intelligence methods, such as Artificial Neural Networks.

Metano entérico de bovinos leiteiros em condições tropicais brasileiras

The objective of this work was to quantify methane (CH4) emission using the sulfur hexafluoride (SF6) tracer technique, by dairy cattle on pasture in Brazilian tropical field conditions. Measurements were performed in the rainy season, with Holstein and Holstein x Zebu crossbred, from lactating and dry cows and heifers grazing fertilized Tobiata grass, and heifers grazing unfertilized Brachiaria grass. Methane and SF6 concentrations were determined by gas chromatograph. Methane emissions by lactating cows varied from 13.8 to 16.8 g/hour, by dry cows from 11.6 to 12.3 g/hour, by heifers grazing fertilized grass was 9.5 g/hour and by heifers grazing unfertilized grass varied from 7.6 to 8.3 g/hour or 66 to 72 kg/head/year. Methane emission per digestive dry matter intake (DMDI) varied from 42 to 69 g/kg DMDI for lactating cows, 46 to 56 g/kg for dry cows, 45 to 58 g/kg for heifers grazing fertilized grass and 58 to 62 g/kg for heifers in unfertilized grass pasture. The CH4 emission measured on dairy cattle feeding tropical grasses was higher than that observed for temperate climate conditions.

Efeitos de dietas contendo Leucaena leucocephala e Saccharomyces cerevisiae sobre a fermentação ruminal e a emissão de gás metano em bovinos

This research was to evaluate the effect of Leucaena (Leucaena leucocephala) and yeast (Saccharomyces cerevisiae) in diets for bovines on ruminal metabolism, including pH, volatile fatty acids, and ammonia and methane production. Four crossbred male cattle (800 kg LW) rumen cannulated were distributed to a 4 × 4 Latin Square design, in 2 × 2 factorial arrangement, composed by two levels of Leucaena (20% and 50% DM) and coast-cross grass hay, with or without yeast. No differences were observed in rumen pH (mean 6.82) and ammonia concentrations that varied from 18.71 to 21.28 mg/100 mL of ruminal fluid. There was interaction between Leucaena levels and yeast in the total concentrations of VFA. No differences were observed in the concentrations of acetic acid, but the animals fed 50% of Leucaena with yeast showed higher propionic acid concentration (19.14 mM). Methane emissions were reduced by 12.3% in relation to the same diet without yeast and in 17.2% when the animals were fed 20% of Leucaena with yeast. There was a noticeable associative effect of Leucaena when fed in high level (50% DM) and yeast in the reduction of methane emission and better rumen fermentation with possible reduction of energy loss and better energy efficiency for the animals.

Evaluation of the synthetic major component of the sex pheromone of Tuta absoluta (Meyrick) (Lepidoptera : Gelechiidae)

In wind-tunnel bioassays, dispensers loaded with 1 μg of the synthetic major component (3E,8Z,11Z)-3,8,11-tetradecatrienyl acetate (TDTA) of the sex pheromone emitted by Tuta absoluta (Meyrick) females were found to be highly attractive to conspecific males. Field experiments were conducted to evaluate the efficacy of five trap designs. The best trap, baited with 100 μg of the synthetic sex pheromone caught on average 1200 males per trap per night, while those baited with virgin females caught only 201 males. The male response to this pheromone is restricted to the same early-morning time window during which females exhibit calling behavior. The high biological activity of the synthetic pheromone suggests that it could be useful for pest monitoring and in mating disruption.

Exsudato glandular de genótipos de tomateiro e desenvolvimento de Bemisia tabaci (Genn.) (Sternorryncha: Aleyrodidae) biótipo B

Bemisia tabaci (Genn.) is one of the most important tomato pests in Brazil and causes severe losses due to the sap suction, the induction of the irregular ripening of the fruit and virus transmission. The objective of this study was to determine the effect of exudates released by the glandular trichomes on the development of B. tabaci biotype B on eight tomato genotypes, under greenhouse conditions. The experiment was arranged as a factorial scheme (genotype x exudate) in a randomized block design, with three replications, being the genotypes evaluated in two conditions (with and without exudate). Whitefly adults were transferred to a voile cage for 24h. The variables evaluated were number of eggs and viability, incubation period, number of nymphs, duration and viability of the nymphal stage. Trichome counts and determination of pH and acylglucose content were made for all the genotypes. Intact leaflets of LA716 were less accepted for oviposition than leaflets without exudate, which suggests an antixenotic effect. Antixenotic resistance in LA1739 and PI134417 was not associated to the glandular exudate. The effect of exudates on the insect oviposition was explained by the acylglucose content. The pH showed secondary role on the whitefly oviposition. Trichomes density improved the insect development. LA1584 reduced the insect survival and increased its cycle, besides promoting an intermediate oviposition. For this reason, it can be useful in breeding programs. However, further studies are needed to determine the potential of this genotype and hybrids for future utilization in integrated pest management.

Effect of lipid sources with different fatty acid profiles on the intake, performance, and methane emissions of feedlot Nellore steers

The present study was conducted to evaluate the effect of lipids with different fatty acid profiles on the intake, performance, and enteric CH4 emission of Nellore steers. A total of 45 Nellore animals with an average initial BW of 419 ± 11 kg (at 15 ± 2 mo) were distributed in a completely randomized design consisting of 5 treatments and 9 replicates. The roughage feed was maize silage (600 g/kg on a DM basis) plus concentrate (400 g/kg on a DM basis). The dietary treatments were as follows: without additional fat (WF), palm oil (PO), linseed oil (LO), protected fat (PF; Lactoplus), and whole soybeans (WS). The lipid source significantly affected (P < 0.05) nutrient intake. The greatest intakes of DM, OM, and CP were observed in the animals that were fed the WF or PF diets, and the lowest intakes were observed in the animals that were fed the PO diet. Intake of NDF decreased (P < 0.05) with the addition of PO. Enteric methane emission (g/kg DMI) was reduced by an average of 30% when the animals were fed diets containing WS, LO, and PO (P < 0.05), and these diets caused a larger reduction in the energy loss in the form of methane compared to those without added fat and with added PF (3.3 vs. 4.7%). The different fatty acid profiles did not affect the backfat thickness or the loin eye area of the animals (P > 0.05). However, animals fed PO displayed lower daily weight gain (0.36 kg/d), feed efficiency (0.08 kg ADG/kg DM), HCW (245 kg), and hot yield percentage (52.6%) compared to animals that were fed the other diets. Therefore, PO compared to the other lipid sources used in this study reduces intake, performance, feed efficiency, and carcass yield. Therefore, PO is not suggested for feedlot-finished animals.

Ruminal methane emission by dairy cattle in Southeast Brazil

Gases gerados durante o processo de fermantacao ruminal, metano em particular, representam nao so uma perda parcial de energia da alimentacao como tambem sao apontados como importantes fatores do efeito-estufa. Quantificaram-se as taxas de emissao de metano (CH4) ruminal por vacas em lactacao, vacas secas e novilhas com idade media de 24 meses, em pastejo sob condicoes tropicais do sudeste brasileiro, utilizando a tecnica do gas tracador hexafluoreto de enxofre (SF6). Foram utilizados quatro animais para cada categoria, distribuidos em quatro blocos. As medicoes foram realizadas em fevereiro e junho de 2002, com animais da raca Holandesa e Mestica Leiteira Holandes ¾ x Gir ¼ - Mesticas, mantidos em pastagem de capim-Tanzânia (Panicum maximum Jacq. cv. Tanzania) e capim-braquiaria (Brachiaria decumbens cv. Basilisk) adubadas, e tambem novilhas de ambas as racas em pastagens de capim-brachiaria sem adubacao, simulando as condicoes de producao extensiva. As concentracoes de CH4 e SF6 foram determinadas por cromatografia gasosa. Foram encontradas diferencas na emissao de metano (p < 0,05) entre os grupos geneticos. Animais da raca holandesa produziram mais metano (299,3 g dia-1) que as mesticas (264,2 g dia-1). Vacas secas e novilhas produzem menos metano (g dia-1) que vacas em lactacao. A media de emissao de metano (g dia-1) pelas vacas secas e novilhas foi de 268,8 e 222,6 g respectivamente e as vacas em lactacao 353,8 g. Os animais da raca holandesa, com maior potencial de producao de leite, perderam menos CH4 (p < 0,05) por unidade de materia seca ingerida (19,1 g kg-1) que as mesticas (22,0 g kg-1). A producao de metano pelas novilhas mantidas em pastagens adubadas (sistema intensivo) foi de 222,6 g dia-1, maior (p < 0,05) que os animais desta categoria em pastagens nao adubadas (179,2 g dia-1). A producao de metano variou em funcao da categoria de animal e pelo sistema de producao imposto aos animais.

Análise integrada de sistemas de produção de tomateiro com base em indicadores edafobiológicos

A analise integrada de indicadores edafobiologicos ligados ao manejo do solo constitui uma ferramenta importante para estimar niveis de sustentabilidade do agroecossistema, detectando-se pontos criticos para a devida correcao de manejo. Essa ferramenta foi empregada na avaliacao de sistemas de producao orgânica e convencional de tomate, em cultivo protegido e a campo aberto, no estado de Sao Paulo. Tomaram-se como referencia solos de mata nativa e/ou pastagem natural, dependendo do local de estudo. Em Serra Negra, o solo sob sistema orgânico apresentou maior capacidade de campo e teor de argila dispersa mais baixo, indicativos da estabilidade dos agregados. No sistema convencional observou-se uma elevada condutividade eletrica, evidenciando a alta disponibilidade de sais soluveis. A analise de componentes principais (ACP) permitiu concluir que ha maior grau de similaridade entre o solo sob sistema orgânico e aqueles das bases referenciais, com respeito aos indicadores quimicos e biologicos. Constatou-se que C org, N total, polissacarideos, FDA (hidrolise de diacetato de fluoresceina) e atividade enzimatica de desidrogenase estao positivamente relacionados com o sistema orgânico, a mata nativa e a pastagem. Em contrapartida, a saturacao por bases (V%), pH, teores de Mn, Mg e Ca, bem como a razao de dispersao estao inversamente relacionadas ao manejo orgânico. Ja em Araraquara, os resultados da ACP distinguiram as areas organicamente cultivadas das matas nativas, principalmente, com base nos indicadores biologicos.

Methane emissions and estimates of ruminal fermentation parameters in beef cattle fed different dietary concentrate levels

Using sorghum silage, the effect of roughage/concentrate ratios was evaluated on nutrient intake, digestibility, ruminal parameters and methane production by beef cattle. Three treatments (0, 30 and 60% of concentrate in DM of the diet) were distributed in three Latin squares, with nine animals and three periods. Dry matter intake increased as the grain concentration in diet increased; pH showed opposite behavior. Methane emissions were lower for animals fed the diet exclusively with sorghum silage as compared with those fed 30% of concentrate, but was similar to that of animals receiving 60% of concentrate. Losses of ingested gross energy as methane were reduced by 33% when grain concentration was increased in the diet. Concentrations of propionic and butyric acids were greater in diets with grain concentrate; acetic acid concentration was not affected. Concentrate in diet increases available energy for the metabolism, measured by lower losses of ingested gross energy as ruminal methane.