Sensibilidade de plantas de eucalipto (Eucalyptus urograndis) à subdoses do herbicida dicamba

In view of the widespread increase in herbicide-resistant weeds, biotechnology companies have developed dicamba-tolerant soybean and cotton cultivars. This technology can, however, increase the risk of the product drifting to adjacent areas. This study was developed with the objective of the to evaluate the phytotoxicity and biometric variables of young eucalyptus plants exposed to subdoses of the herbicide dicamba. The experiment was carried out under field conditions in Rio Verde, state of Goiás, Brazil. The treatments were represented by the application of 0 (control), 7.5, 15, 30, 60, 120 or 240 g ae ha-1 of dicamba 45 days after the seedlings were planted in the field. In terms of phytotoxicity, the dicamba doses of 120 and 240 g ae ha-1 caused greater damage to the eucalyptus plants in all periods of evaluation. The predominant symptoms were epinasty, increased number of shoots and necrosis and senescence of young branches and leaves. The herbicide doses of 120 and 240 g ae ha-1 significantly compromised plant height and diameter, number of branches and dry mass of leaves and roots, interfering with the growth and development of the eucalyptus crop. The results indicate that the effect of subdoses of the herbicide dicamba can interfere with the proper development of young eucalyptus plants, which may cause losses in the initial planting phase and future losses for producers.Em decorrência do aumento generalizado de plantas daninhas com resistência a herbicidas, empresas de biotecnologia desenvolveram cultivares de soja e algodão tolerantes ao herbicida dicamba. Essa tecnologia pode, no entanto, aumentar o risco do produto ser deslocado para áreas adjacentes às aplicadas. Neste trabalho objetivou-se avaliar a fitotoxicidade e variáveis ​​biométricas de plantas jovens de eucalipto tratadas com subdoses do herbicida dicamba. O experimento foi realizado em condições de campo em Rio Verde, Goiás, Brasil. Os tratamentos foram representados pela aplicação de 0 (testemunha), 7,5, 15, 30, 60, 120 ou 240 g ea ha-1 de dicamba aos 45 dias após o plantio das mudas no campo. Em termos de fitotoxicidade, as doses de dicamba de 120 e 240 g ea ha-1 causaram maiores danos às plantas de eucalipto em todos os períodos de avaliação. Os sintomas predominantes foram epinastia, aumento do número de brotações e necrose e senescência de ramos e folhas jovens. As doses de herbicidas de 120 e 240 g ea ha-1 comprometeram significativamente a altura e diâmetro das plantas, número de ramos e massa seca de folhas, caules e raízes, interferindo no crescimento e desenvolvimento da cultura do eucalipto. Os resultados indicam que o efeito de subdoses do herbicida dicamba pode interferir no bom desenvolvimento de plantas jovens de eucalipto, podendo causar prejuízos na fase inicial de plantio e prejuízos futuros para os produtores

Listening to Music in the First, but not the Last 1.5 km of a 5-km Running Trial Alters Pacing Strategy and Improves Performance

We examined the effects of listening to music on attentional focus, rating of perceived exertion (RPE), pacing strategy and performance during a simulated 5-km running race. 15 participants performed 2 controlled trials to establish their best baseline time, followed by 2 counterbalanced experimental trials during which they listened to music during the first (M-start) or the last (M-finish) 1.5 km. The mean running velocity during the first 1.5 km was significantly higher in M-start than in the fastest control condition (p < 0.05), but there was no difference in velocity between conditions during the last 1.5 km (p > 0.05). The faster first 1.5 m in M-start was accompanied by a reduction in associative thoughts compared with the fastest control condition. There were no significant differences in RPE between conditions (p > 0.05). These results suggest that listening to music at the beginning of a trial may draw the attentional focus away from internal sensations of fatigue to thoughts about the external environment. However, along with the reduction in associative thoughts and the increase in running velocity while listening to music, the RPE increased linearly and similarly under all conditions, suggesting that the change in velocity throughout the race may be to maintain the same rate of RPE increase.Australian Department of Education, Employment and Workplace RelationsAustralian Department of Education, Employment and Workplace Relation

Suplementação de nitrato e sua relação com a formação de óxido nítrico e exercício físico

A ingesto de nitrato vem crescendo em popularidade no meio esportivo. Esta reviso objetiva esclarecer os mecanismos responsveis pelo efeito da suplementao de nitrato relacionadas ao xido ntrico, bem como descrever os efeitos agudos e crnicos da suplementao com nitrato sobre o desempenho. O xido ntrico um radical livre endgeno de meia vida curta e contribui de forma significativa na regulao de muitas funes corporais tais como: contratilidade muscular, metabolismo energtico, mensageiro intercelular, citotoxicidade mediada por macrfagos, inibio da agregao plaquetria, presso arterial, fluxo sanguneo e respirao mitocondrial. A suplementao com nitrato aumenta a disponibilidade de xido ntrico no organismo, este por sua vez age sobre a mitocndria promovendo efeitos importantes no consumo de oxignio durante o exerccio. Tem sido demonstrado que a suplementao diettica com nitrato acarreta aumento no tempo de exausto durante exerccios de alta intensidade, melhora no desempenho em exerccios contra relgio e promove reduo significativa no consumo de oxignio pulmonar em intensidades submximas. Por outro lado, apesar de haver tendncia ao uso de suco de beterraba, no existe consenso em relao forma de administrao de nitrato, tampouco conformidade quanto a melhor dose resposta

Prior Exercise Reduces Fast-Start Duration and End-Spurt Magnitude during Cycling Time-Trial

We examined the pacing strategy and the magnitude of the end spurt during a 200-kJ cycling time trial performed 12–14 h after an exercise protocol designed to reduce muscle glycogen content. 9 physically-active men performed 5 familiarization sessions and 2 experimental 200-kJ time trials in either a control condition (CON) or after an exercise protocol performed the previous evening that was designed to induce muscle glycogen depletion (EP). Mean total time was faster and power output was higher in the CON than in the EP (P<0.01). A fast-start was maintained until the 50-kJ section in CON, but only the 25-kJ section for EP (P<0.05). The power outputs during the 50-, 150- and 200-kJ sections, and the magnitude of the end-spurt, were significantly higher for the CON than for the EP condition (P<0.05). There was no significant difference in the rating of perceived exertion (overall feeling and feeling in legs) between conditions. In conclusion, a protocol designed to decrease muscle glycogen stores reduced the duration of the fast-start and the magnitude of the end spurt during a 200-kJ cycling time trial, impairing the overall performance

VARIÁVEIS FISIOLÓGICAS ASSOCIADAS COM O DESEMPENHO EM PROVAS DE LONGA DURAÇÃO: das tradicionais as contemporâneas

Diversas variáveis fisiológicas têm sido associadas com o desempenho em provas de longa duração. Sendo assim, o objetivo dessa revisão é apresentar evidencias da relação entre as principais variáveis fisiológicas associadas com o desempenho aeróbio para modalidades de longa duração. Para tanto foi realizada um busca eletrônica no banco de dados PubMed, sendo selecionados estudos desde 1923 até os mais recentes. Com base nos estudos apresentados nesta revisão, pode-se compreender que a utilização de somente uma variável fisiológica pode ser insuficiente para representar a aptidão aeróbia para modalidades de longa duração

The effects of acute and chronic sprint-interval training on cytokine responses are independent of prior caffeine intake

We examined the effect of acute and chronic sprint interval training (SIT), with or without prior caffeine intake, on levels of exercise-induced inflammatory plasma cytokines [interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α]. Twenty physically-active men ingested either a placebo (n = 10) or caffeine (n = 10) 1 h before each SIT session(13-s × 30-s sprint/15 s of rest) during six training sessions (2 weeks). The early (before, immediately after, and 45 min after the exercise) and late (24 and 48 h after the exercise) cytokine and creatine kinase (CK) responses were analyzed for the first and last training sessions. Plasma IL-6 and IL-10 peaked 45 min after the exercise, and then returned to basal values within 24 h (p \u3c 0.05) in both groups on both occasions (p \u3e 0.05). On both occasions, and for both groups, plasma TNF-α increased from rest to immediately after the exercise and then decreased at 45 min before reaching values at or below basal levels 48 h after the exercise (p \u3c 0.05). Serum CK increased from rest to 24 and 48 h post-exercise in the first training session (p \u3c 0.05), but did not alter in the last training session for the PLA group (p \u3e 0.05). Serum CK was unchanged in both the first and last training sessions for the CAF group (p \u3e 0.05). Two weeks of SIT induced a late decrease in the IL-6/IL-10 ratio (p \u3c 0.05) regardless of caffeine intake, suggesting an improved overall inflammatory status after training. In conclusion, a single session of SIT induces muscle damage that seems to be mitigated by caffeine intake. Two weeks of SIT improves the late SIT-induced muscle damage and inflammatory status, which seems to be independent of caffeine intake

First records of Chthonerpeton arii Cascon and Lima-Verde, 1994 (Amphibia: Gymnophiona: Typhlonectidae) out of the type locality

Chthonerpeton arii was described from a large series of specimens from Limoeiro do Norte municipality, state of Ceará, Brazil. Here we provide the first records of the species out of the type locality, in the state of Bahia, and in its border with the state of Pernambuco, Brazil. We also provide color photographs of a preserved specimen

FENOLOGIA REPRODUTIVA DA ESPÉCIE Carapa guianensis Aubl. (ANDIROBEIRA) EM ECOSSISTEMAS DE TERRA FIRME E VÁRZEA, AMAPÁ, BRASIL.

The aspects phenology of Carapa guianensis Aubl. are presented, related to the precipitation pluviometric of the region, in two ecosystems of natural occurrence of the species. The period of monthly observation was of 28 months. The flowering phenophase was more evidenced in the period of smaller precipitation pluviometric, while the fructification happened with larger intensity during the months of larger precipitation pluviometric the species presented annual pattern in the phenophases flowering and fructification in the studied period. Regarding the change to foliate, the pattern perennial was detected with fall of leaves during the whole year in the two environments.Keyword: Amazon, ecology, pluviometric.São apresentados aspectos fenológicos de Carapa guianensis Aubl., relacionados à precipitação pluviométrica da região, em dois ecossistemas de ocorrência natural da espécie. O período de monitoramento mensal foi de 28 meses. A fenofase de floração foi mais evidenciada no período de menor precipitação pluviométrica, enquanto que a frutificação ocorreu com maior intensidade durante os meses de maior precipitação pluviométrica. A espécie apresentou padrão anula nas fenofases floração e frutificação no período estudado. Com relação à mudança foliar, foi detectado o padrão perenifólio com queda de folhas durante o ano todo nos dois ambientes.Palavras-chave: Amazônia, ecologia, pluviometria