Manejo de plantas daninhas na cultura do algodoeiro em sistema de plantio direto

Este trabalho foi realizado com objetivo de avaliar a eficiência dos herbicidas smetolachlor, em pré-emergência, e trifloxysulfuron-sodium, aplicado aos 18 dias após a emergência do algodão (DAE), em sistema de plantio direto. Foi utilizado o arranjo fatorial (4 x 4) + 1, sob delineamento de blocos casualizados, com quatro repetições. O primeiro fator constituiu-se de quatro doses de S-metolachlor (0, 384, 768 e 1.152 g ha-1) e o segundo de quatro doses de trifloxysulfuron-sodium (0,0; 2,625; 5,250; e 7,875 g ha-1), mais uma testemunha mantida no limpo por todo o ciclo do algodoeiro. As plantas daninhas foram avaliadas aos 25, 45 e 60 DAE. Na área, foi verificada a presença das seguintes espécies daninhas: Alternanthera tenella (apaga-fogo), representando mais de 80% do total, Tridax procumbens (erva-de-touro), Bidens sp. (picão-preto), Acanthospermum hispidum (carrapicho-de-carneiro), Cenchrus echinatus (capim-carrapicho), Digitaria horizontalis (capimcolchão), Eleusine indica (capim-pé-de-galinha) e Commelina benghalensis (trapoeraba). O S-metolachlor apresentou baixa eficiência de controle destas espécies, no entanto o trifloxysulfuron-sodium teve seu desempenho melhorado quando foi aplicado S-metolachlor. O melhor controle foi obtido com a combinação de S-metolachlor a 1.152 g ha-1 com trifloxysulfuron-sodium a 7,875 g ha-1, que apresentou controle superior a 90% de A. tenella e do total de plantas daninhas até 60 DAE. Todavia, esse controle não foi suficiente para permitir a colheita do algodão no limpo. As combinações de S-metolachlor a 384 e 768 g ha-1 com trifloxysulfuron-sodium a 7,875 g ha-1 e de S-metolachlor a 1.152 g ha-1 com trifloxysulfuron-sodium nas doses de 5,250 e 7,875 g ha-1 proporcionaram rendimentos semelhantes aos da testemunha capinada.

Efeito do protetor dietholate na seletividade de clomazone em cultivares de arroz irrigado

No arroz irrigado, o herbicida clomazone tem sua seletividade variável de acordo com o cultivar, o tipo de solo e a dose aplicada. O uso do protetor dietholate permite seletividade em diferentes ambientes, sendo necessário o estudo da relação entre esses fatores. Em vista do exposto, objetivou-se com este experimento quantificar a seletividade do herbicida clomazone em função de cultivares de arroz irrigado, tipos de solos, doses de clomazone e tratamento de sementes com dietholate. O experimento foi conduzido em casa de vegetação, em delineamento de blocos ao acaso, em esquema fatorial com quatro repetições. O fator A foi composto por tipos de solo (arenoso e argiloso); o fator B, por cultivares de arroz irrigado (IRGA 409 e IRGA 417); o fator C, pela ausência do protetor dietholate; e o fator D, por doses de clomazone (0, 156, 312, 625, 1.250, 2.500, 5.000 e 10.000 g ha-1) aplicadas em pré-emergência do arroz irrigado. Dezoito dias após a semeadura do arroz, foram avaliados a fitotoxicidade e o percentual de redução de massa fresca e seca da parte aérea das plantas de arroz. Os cultivares de arroz toleram maiores doses de clomazone quando tratados com dietholate e semeados em solos com maior teor de argila e matéria orgânica. Em solo arenoso, a toxicidade do herbicida nas plantas de arroz foi maior, na ordem de 50%, quando se comparou com a mesma dose em solo argiloso.

Phorate e dietholate protegem o arroz da fitotoxicidade do clomazone em doses elevadas

O herbicida clomazone tem sua seletividade às plantas de arroz aumentada quando as sementes recebem o protetor dietholate. Sabendo que o dietholate atua sobre a atividade da enzima citocromo P-450 mono-oxigenase e que esta é responsável pela ativação do clomazone, buscam-se outros produtos que possam ser utilizados como protetores. Em vista disso, o objetivo deste experimento foi avaliar o efeito protetor do dietholate e do phorate em função de doses de clomazone. O delineamento experimental foi de blocos ao acaso com quatro repetições, em esquema fatorial. O fator A foi composto pelo tratamento de sementes com dietholate ou phorate, além de uma testemunha, que não recebeu protetor nas sementes. O fator B foi composto por oito doses de clomazone (0, 156, 312, 625, 1.250, 2.500, 5.000 e 10.000 g i.a. ha-1). Dezoito dias após a semeadura, foram avaliados a fitotoxicidade, o percentual de redução da estatura e a massa fresca e seca das plantas de arroz. Os dados foram submetidos à análise da variância, por meio da regressão não linear do tipo logístico. Houve diferença entre a testemunha sem protetor e os tratamentos de sementes com os protetores dietholate e phorate. Analisando as curvas de dose-resposta, verifica-se que, quando sementes do cultivar IRGA 417 foram tratadas com dietholate ou com phorate, ambos protegeram as plântulas de arroz do clomazone, ou seja, as plantas foram capazes de tolerar maiores doses de clomazone. Assim, há evidências de que os protetores de plantas dietholate e phorate atuam como inibidores da enzima citocromo P-450, impedindo que ela ative o clomazone nas plantas de arroz, proporcionando maior seletividade deste herbicida quando comparado à testemunha que não recebeu proteção.

Seletividade de herbicidas aplicados em pré-emergência em gramíneas forrageiras

O presente trabalho teve o objetivo de avaliar a seletividade de herbicidas aplicados em pré-emergência sobre a produção e a qualidade de sementes de Brachiaria brizantha cv. Marandu e Brachiaria decumbens cv. Basilisk. Os herbicidas avaliados foram: diuron (800 e 1.600 g ha-1), ametryn (625 e 1.250 g ha-1), imazaquin (75 e 150 g ha-1), imazethapyr (50 e 100 g ha-1) e flumetsulam (70 e 140 g ha-1), além de uma testemunha sem aplicação de herbicidas. As espécies foram avaliadas separadamente no campo. Os experimentos foram instalados no delineamento em blocos casualizados com quatro repetições. Os herbicidas ametryn (625 g ha-1), imazaquin (75 e 150 g ha-1), imazethapyr (50 e 100 g ha-1) e flumetsulam (70 e 140 g ha-1) foram os que proporcionaram maior seletividade às plantas de B. brizantha, enquanto para B. decumbens o diuron (800 e 1.600 g ha-1), o ametryn (625 e 1.250 g ha-1) e o imazethapyr (50 e 100 g ha-1) foram mais seletivos, destacando-se o diuron na menor dose. Contudo, os herbicidas avaliados não alteram a produção e a qualidade das sementes das forrageiras estudadas.

Optimizing activity of herbicides at reduced rate on Emex spinosa campd. with adjuvants

In pot experiments, two adjuvants were evaluated for their efficacy in enhancing activity of five herbicides applied at reduced rates (75% of the recommended rates) on Emex spinosa at the cotyledon-leaf and at the two- to four- leaf stage. Herbicides (at recommended rates) including fluroxypyr+MCPA at 450 g a.i. ha-1, carfentrazone-ethyl at 20 g a.i. ha-1, bromoxynil+MCPA at 450 g a.i. ha-1, thifensulfuron-methyl at 75 g a.i. ha-1 and tribenuronmethyl at 75 g a.i. ha-1 alone and tank mixed at reduced rates with adjuvants, namely, alkyl ether sulphate sodium salt at 625 mL ha-1 or fatty alcohol ethoxylate at 375 mL ha-1. Addition of the adjuvants to reduced rates of fluroxypyr+MCPA and carfentrazone-ethyl, increased their efficacy with 100% mortality and biomass reduction of E. spinosa at the cotyledon- leaf stage and at the two- to four- leaf stage which was similar to their recommended rates without the adjuvants except for carfentrazone-ethyl at a reduced rate without adjuvants at the two- to four- leaf stage. Bromoxynil+MCPA at reduced rates with alkyl ether sulphate sodium salt also gave 100% control of E. spinosa over weedy check at the two- to four- leaf stage. Both the adjuvants generally increased the efficacy of tribenuron-methyl at reduced rates when sprayed at both leaf stages. These findings suggest that the use of adjuvants may increase the efficacy of the above mentioned herbicides against E. spinosa and it may be incorporated in an integrated weed management program.

Weed suppression in the formation of brachiarias under three sowing methods

The success of conservation systems such as no-till depends on adequate soil cover throughout the year, which is possible through the use of cover crops. For this purpose the species belonging to the genus Urochloa has stood out by virtue of its hardiness and tolerance to drought. Aiming ground cover for the no-till system, the objective was to evaluate the establishment of two species of the genus Urochloa, in three sowing methods, in the weed suppression and the sensitivity of these forages to glyphosate. The study design was a randomized block with a 2 x 3 x 3 factorial arrangement, in which factor A was composed of Urochloa ruziziensis and Urochloa hybrid CIAT 36087 cv. Mulato II, factor B was formed by sowing methods: sown without embedding, sown with light embedding and sown in rows, and factor C was composed of three doses of glyphosate (0.975, 1.625 and 2.275 kg ha-1 of acid equivalent). For determination of weed suppression, assessment of biomass yield and soil cover was performed, by brachiaria and weeds, at 30, 60, 90, 120 and 258 days after sowing. Visual assessment of the desiccation efficiency at 7 and 14 days after herbicide application was performed. It is concluded that embedding Urochloa seeds stands out in relation to sowing in the soil surface. Urochloa ruziziensis is more efficient in the dry weight yield, weed suppression, in addition to being more sensitive to glyphosate herbicide.

SELECTIVITY OF FOMESAFEN TO COTTON

ABSTRACT The aim of this work was to evaluate the selectivity of fomesafen alone or in a tank mixture with other preemergent herbicides, with or without S-metolachlor application in early postemergence in cotton plant, cultivar DP 555 BG RR(r). The design utilized was a randomized complete block, organized in a split-plot arrangement, with four replications. For that, 24 herbicides were evaluated with fomesafen (0.45 and 0.625 kg ha-1), prometryn (1.25 kg ha-1), diuron (1.25 kg ha-1), trifluralin (1.8 kg ha-1), and S-metolachlor (0.77 kg ha-1), applied as preemergent, with or without S-metolachlor (0.77 kg ha-1) applied in early postemergence. The variables evaluated were: phytotoxicity, insertion height of the first reproductive branch, plant height, stand, number of reproductive branches per plant, number of bolls per plant, bolls weight, and productivity of cotton seed. Fomesafen alone or in a tank mixture with preemergent prometryn, diuron, trifluralin and S-metolachlor was selective to cotton plant. Preemergent fomesafen isolated application followed by the application of S-metolachlor in early postemergence was also selective. However, on average, preemergent tank mixtures applied in association with preemergent S-metolachlor early application was not selective to cotton crop.

Florística e fitossociologia dos estratos arbustivo e arbóreo de um remanescente de cerradão em uma Unidade de Conservação do Estado de São Paulo

Neste trabalho foram empregadas 25 parcelas permanentes de 10 m × 25 m e amostrada a vegetação com DAS (Diâmetro à Altura do Solo) igual e superior a 1,0 cm. Em uma área de 0,625 ha foram amostrados 8.454 ind.ha-1, 121 espécies, 74 gêneros e 42 famílias. As espécies de maior IVI foram Ocotea corymbosa (Meissn.) Mez, Pterodon pubescens Benth. e Xylopia aromatica (Lam.) Mart. Os altos valores de PSoR e de IVIA mostraram que O. corymbosa e P. pubescens estão representadas nos três estratos da comunidade, embora essas espécies predominem no estrato superior. O índice de Shannon mostrou alta diversidade florística (H' = 3,47 nat.ind.-1) e o índice de eqüabilidade (J' = 0,40) indicou dominância de P. pubescens e O. corymbosa na área. As distribuições diamétrica e de altura revelaram a abundância no componente da regeneração natural devido ao grande estoque de plantas jovens que compõem o estrato inferior da comunidade. Dentre as 114 espécies consideradas na análise fitossociológica, 20 podem ser classificadas como raras por apresentarem baixa densidade de indivíduos por hectare. O levantamento florístico caracterizou a fitofisionomia da área como cerradão. A estimativa dos parâmetros fitossociológicos verticais permitiu valorar as espécies através da PSoR e do IVIA, associando a estrutura fitossociológica horizontal com a heterogeneidade e irregularidade dos estratos do cerradão da área do Oitocentos Alqueires.

Genetic control of characters associated with bean golden mosaic geminivirus resistance in Phaseolus vulgaris L.

Bean golden mosaic is the most important viral disease of the bean crop (Phaseolus vulgaris L.) in Latin America. The genetics of resistance to a Brazilian strain of bean golden mosaic virus (BGMV), was studied in a 4 x 4 diallel cross without reciprocals, among the parental genotypes DOR 303, EMGOPA 201 Ouro, Carnaval, and Redlands Greenleaf C. Seedlings of the four parents, six F1 hybrids, 12 backcrosses, and F2 generations for each combination were inoculated on the eighth day after sowing by exposure to a viruliferous whitefly (Bemisia tabaci Genn.) population for 24 h, in a glasshouse, prior to transplantation to field conditions. The full set of two parents, F1, F2 and respective backcrosses for each combination was considered to be a family. Data were recorded and analyzed for foliar yellowing, plant dwarfing, and pod malformation, using a randomized block design, with two replications. Weighted generation mean analysis was performed for each of the six families. An additive gene action model was significant for the three characteristics evaluated. On the other hand, non-additive gene action had greater absolute value in most cases. Resistance to foliar yellowing conferred by genes from DRO 303 was highly heritable and was expressed equally well in the different genetic backgrounds evaluated. Such resistance may be oligogenic. Broad- and narrow-sense heritabilities were relatively high for all response traits. The three traits studied were all positively correlated, indicating that they can be simultaneously selected for enhancement. The highest correlation coefficient was obtained for dwarfing x pod malformation.

Detection of specific IgE antibodies in parasite diseases

Activation of Th1 or Th2 cells is associated with production of specific immunoglobulin isotypes, offering the opportunity to use antibody measurement for evaluation of T cell function. Schistosomiasis and visceral leishmaniasis are diseases associated with Th2 activation. However, an IgE response is not always detected in these patients. In the present study we evaluated specific IgE antibodies to S. mansoni and L. chagasi antigens by ELISA after depletion of serum IgG with protein G immobilized on Sepharose beads or RF-absorbent (purified sheep IgG antibodies anti-human IgG). In schistosomiasis patients, specific IgE to SWAP antigen was demonstrable in only 10 of 21 patients (48%) (mean absorbance ± SD = 0.102 ± 0.195) when unabsorbed serum was used. Depletion of IgG with protein G increased the number of specific IgE-positive tests to 13 (62%) and the use of RF-absorbent increased the number of positive results to 20 (95%) (mean absorbances ± SD = 0.303 ± 0.455 and 0.374 ± 0.477, respectively). Specific IgE anti-L. chagasi antibodies were not detected in unabsorbed serum from visceral leishmaniasis patients. When IgG was depleted with protein G, IgE antibodies were detected in only 3 (11%) of 27 patients, and the use of RF-absorbent permitted the detection of this isotype in all 27 visceral leishmaniasis sera tested (mean absorbance ± SD = 0.104 ± 0.03). These data show that the presence of IgG antibodies may prevent the detection of a specific IgE response in these parasite diseases. RF-absorbent, a reagent that blocks IgG-binding sites and also removes rheumatoid factor, was more efficient than protein G for the demonstration of specific IgE antibodies.

Hormone replacement therapy increases levels of antibodies against heat shock protein 65 and certain species of oxidized low density lipoprotein

Hormone replacement therapy (HRT) reduces cardiovascular risks, although the initiation of therapy may be associated with transient adverse ischemic and thrombotic events. Antibodies against heat shock protein (Hsp) and oxidized low density lipoprotein (LDL) have been found in atherosclerotic lesions and plasma of patients with coronary artery disease and may play an important role in the pathogenesis of atherosclerosis. The aim of the present study was to assess the effects of HRT on the immune response by measuring plasma levels of antibodies against Hsp 65 and LDL with a low and high degree of copper-mediated oxidative modification of 20 postmenopausal women before and 90 days after receiving orally 0.625 mg equine conjugate estrogen plus 2.5 mg medroxyprogesterone acetate per day. HRT significantly increased antibodies against Hsp 65 (0.316 ± 0.03 vs 0.558 ± 0.11) and against LDL with a low degree of oxidative modification (0.100 ± 0.01 vs 0.217 ± 0.02) (P<0.05 and P<0.001, respectively, ANOVA). The hormone-mediated immune response may trigger an inflammatory response within the vessel wall and potentially increase plaque burden. Whether or not this immune response is temporary or sustained and deleterious requires further investigation.

An improved HPLC method for the quantitation of 6-mercaptopurine and its metabolites in red blood cells

A procedure is described for the rapid determination of the intra-erythrocyte concentration of 6-mercaptopurine (6-MP) and its metabolites, 6-thioguanine nucleotides (6-TGN) and 6-methylmercaptopurine (6-MMP). Erythrocytes (8 x 10(8) cells) in 350 µl Hanks solution containing 7.5 mg dithiothreitol were treated with 50 µl 70% perchloric acid. The precipitate was removed by centrifugation (13,000 g) and the supernatant hydrolyzed at 100°C for 45 min. After cooling, 100 µl was analyzed directly by HPLC using a Radialpack Resolve C18 column eluted with methanol-water (7.5:92.5, v/v) containing 100 mM triethylamine. 6-TG, 6-MP and the hydrolysis product of 6-MMP, 4-amino-5-(methylthio)carbonyl imidazole, were monitored at 342, 322 and 303 nm using a Shimadzu SPD-M10A diode array UV detector. The analytes eluted at 5.3, 6.0 and 10.2 min, respectively. The calibration curves were linear (r² > 0.998), and the analytical recoveries were 73.2% for 6-TG, 119.1% for 6-MP and 97.4% for 6-MMP. The intra- and inter-assay variations were highest for 6-MP (9.6 and 14.3%, respectively). The lowest detectable concentrations were 3, 3 and 25 pmol/8 x 10(8) erythrocytes for 6-TG, 6-MP and 6-MMP, respectively. The quantification limits (coefficients of variation <15%) were 8, 10 and 70 pmol/8 x 10(8) erythrocytes for 6-TG, 6-MP and 6-MMP, respectively. The method was applied to the analysis of 183 samples from 36 children under chemotherapy for acute lymphoblastic leukemia. The concentrations of the metabolites in the red cells of the patients ranged from 0 to 1934 pmol/8 x 10(8) erythrocytes for 6-TGN, and from 0 to 105.8 and 0 to 45.9 nmol/8 x 10(8) erythrocytes for 6-MP and 6-MMP, respectively. The procedure gave results that were in agreement with those obtained with other methods designed to detect cases of non-compliance with treatment, including patient interviews and medical evaluation, among others, demonstrating its applicability to monitoring the treatment of leukemic children.

Effect of sexual steroids on the calcium content of aortic atherosclerotic plaque of oophorectomized rabbits

We determined the effect of conjugated equine estrogen plus medroxyprogesterone acetate on calcium content of aortic atherosclerotic lesions in oophorectomized adult New Zealand rabbits submitted to a cholesterol rich diet. Five groups of 10 animals each were studied: G1 = control, G2 = cholesterol diet only, G3 = diet plus conjugated equine estrogen (0.625 mg/day); G4 and G5 = diet, conjugated equine estrogen (0.625 mg/day) plus medroxyprogesterone acetate (5 and 10 mg/day, respectively). Mean weight varied from 2.7 ± 0.27 to 3.1 ± 0.20 kg (P = 0.38) between groups at the beginning and 3.1 ± 0.27 to 3.5 ± 0.20 kg (P = 0.35) at the end of the experiment. Cholesterol and triglyceride levels were determined at the time of oophorectomy, 21 days after surgery (time 0), and at the end of follow-up of 90 days. The planimetric method was used to measure plaque and caryometric method for histopathologic examination of the aorta. Calcium content was determined by the method of von Kossa. A similar increase in cholesterol occurred in all treated groups without differences between them at the end of the study. Groups G4 and G5 had smaller areas of atherosclerotic lesions (2.33 ± 2.8 and 2.45 ± 2.1 cm², respectively) than the groups receiving no progestogens (G2: 5.6 ± 4 and G3: 4.6 ± 2.8 cm²; P = 0.02). The relation between lesion area and total aorta area was smaller in groups treated with combined drugs compared to the groups receiving no progesterone (G4: 14.9 ± 13 and G5: 14.2 ± 13.4 vs G2: 35.8 ± 26 and G3: 25 ± 8 cm², respectively; P = 0.017). Oral conjugated equine estrogen (0.625 mg/day) plus medroxyprogesterone acetate (5 or 10 mg/day) provoked a greater reduction in atherosclerotic plaque area and calcium content in treated groups, suggesting a dose-dependent effect.

Antitrichomonal and antioxidant activities of Dorstenia barteri and Dorstenia convexa

Dorstenia barteri and D. convexa extracts and some isolated components of the former were investigated for effectiveness against Trichomonas gallinarum and compared with quercetin and quercitrin. The antioxidant activity of the extracts/compounds was also determined. The minimum lethal concentrations (MLCs) for the extract of D. barteri leaves and twigs at 24 h were found to be 15.625 and 15.625 µg/ml, respectively. However, the MLCs of the leaf and twig extract of D. convexa were 125 and 437.5 µg/ml, respectively. The prenylated and geranylated chalcones were as active as the prenylated flavones, 6-prenylapigenin and the diprenylated derivative 6,8-diprenyleridictyol. The order of the antitrichomonal activity of the compounds at 24 h was: quercetin (0.121 µg/ml) > quercitrin (0.244 µg/ml) > or = bartericin B (0.244 µg/ml) > bartericin A (0.73 µg/ml) > stigmasterol (0.98 µg/ml) > 6,8-diprenyleridictyol = isobavachalcone = dorsmanin F (31.25 µg/ml). D. barteri extracts, quercitrin, and bartericin A, and the prenylated flavonoids had potent antioxidant properties. The twig extract of D. barteri was more potent than the leaf extract. Moderate (EC50 >50 µg/ml) and high (EC50 <50 µg/ml) antioxidant activities were detected in the leaf and twig extracts of D. barteri and the prenylated flavonoids. Prenylated flavonoids and the isolated compounds with antioxidant properties described here may account for the anti-inflammatory action of these extracts. The antitrichomonal and antioxidant activities shown by the extracts and compounds in this study are consistent with the ethnomedicinal and local use of the Dorstenia species studied.

High baseline serum total and LDL cholesterol levels are associated with MDR1 haplotypes in Brazilian hypercholesterolemic individuals of European descent

The MDR1 gene encodes the P-glycoprotein, an efflux transporter with broad substrate specificity. P-glycoprotein has raised great interest in pharmacogenetics because it transports a variety of structurally divergent drugs, including lipid-lowering drugs. The synonymous single-nucleotide polymorphism C3435T and the nonsynonymous single-nucleotide polymorphism G2677T/A in MDR1 have been indicated as potential determinants of variability in drug disposition and efficacy. In order to evaluate the effect of G2677T/A and C3435T MDR1 polymorphisms on serum levels of lipids before and after atorvastatin administration, 69 unrelated hypercholesterolemic individuals from São Paulo city, Brazil, were selected and treated with 10 mg atorvastatin orally once daily for four weeks. MDR1 polymorphisms were analyzed by PCR-RFLP. C3435T and G2677T polymorphisms were found to be linked. The allelic frequencies for C3435T polymorphism were 0.536 and 0.464 for the 3435C and 3435T alleles, respectively, while for G2677T/A polymorphism allele frequencies were 0.580 for the 2677G allele, 0.384 for the 2677T allele and 0.036 for the 2677A allele. There was no significant relation between atorvastatin response and MDR1 polymorphisms (repeated measures ANOVA; P > 0.05). However, haplotype analysis revealed an association between T/T carriers and higher basal serum total (TC) and LDL cholesterol levels (TC: 303 ± 56, LDL-C: 216 ± 57 mg/dl, respectively) compared with non-T/T carriers (TC: 278 ± 28, LDL-C: 189 ± 24 mg/dl; repeated measures ANOVA/Tukey test; P < 0.05). These data indicate that MDR1 polymorphism may have an important contribution to the control of basal serum cholesterol levels in Brazilian hypercholesterolemic individuals of European descent.