Differential tolerance of sugarcane cultivars to clomazone

Weed control is one of the most relevant costs of sugarcane production. If weeds are not controlled at the right time, the productivity and longevity of sugarcane plantations are reduced. In this crop, chemical control is the most used method, since it is efficient and it has a lower cost. Differentiated tolerance of sugarcane cultivars to the herbicide clomazone has been observed in the fields. However, there is no scientific evidence of this effect on the productivity of crops. This study evaluated the effects of clomazone on three sugarcane cultivars (RB966928, RB93579 and RB867515). Herbicide application was performed 40 days after the emergence of sugarcane plants and 7, 14, 21 and 28 days after the application, the toxicity caused by the herbicide in the culture was evaluated through grades ranging from 0 (no toxicity) to 100 (plant death). The harvest was performed 580 days after the herbicide application. On this occasion, the length and diameter of the stem, number of tillers, tons of stems per hectare, total soluble solids of the juice, sucrose of the juice, apparent purity of the juice, sugarcane fiber, reducing sugars and total recoverable sugars were evaluated. The differential tolerance among sugarcane cultivars in response to clomazone application in the early stages of crop development was confirmed. Nevertheless, in all cultivars, the symptoms of intoxication disappeared over time and did not reflect on crop productivity. It was concluded that plant control in the sugarcane crop with clomazone, following the recommendation of the manufacturer, does not interfere negatively in the growth, development and productivity of the crop.As plantas daninhas, se não controladas no momento adequado, reduzem a produtividade e longevidade dos canaviais. Nesta cultura, o método químico de controle das plantas daninhas, por ser eficiente e de menor custo, é o mais utilizado. No campo, tem-se observado tolerância diferenciada de cultivares de cana-de-açúcar ao herbicida clomazone. Contudo, não existe comprovação científica desse efeito sobre a produtividade dos cultivares. Neste trabalho foram avaliados os efeitos do clomazone em três cultivares de cana-de-açúcar (RB966928, RB93579 e RB867515). A aplicação do herbicida foi feita aos 40 dias após emergência das plantas de cana, e aos 7, 14, 21 e 28 dias após a aplicação foram avaliadas as intoxicações causadas pelo herbicida na cultura, atribuindo-se notas que variaram de 0 (ausência de intoxicação) até 100 (morte das plantas). Aos 580 dias após a aplicação foi realizada a colheita da cultura. Nessa ocasião, foram avaliados o comprimento e diâmetro do colmo, número de perfilho, tonelada de colmos por hectare, sólidos solúveis totais do caldo, sacarose do caldo, pureza aparente do caldo, fibra da cana, açúcares redutores e açúcares totais recuperáveis. Foi confirmada a tolerância diferenciada entre cultivares de cana-de-açúcar à aplicação do clomazone no início de desenvolvimento da cultura. Entretanto, os sintomas de intoxicação desapareceram ao longo do tempo e não refletiram na produtividade da cultura. Concluiu-se que o controle de plantas na cultura da cana-de-açúcar com o clomazone, seguindo a recomendação do fabricante, não interfere no crescimento, no desenvolvimento e na produtividade da cultura

Spirulina does not decrease muscle damage nor oxdidative stress in cycling athletes with adequate nutritional status

The objective of this study was to assess the effect of Spirulina maxima on oxidative stress and muscle damage in cycling athletes subjected to high volume and intensity of training. Eighteen male athletes were randomly divided into an experimental group (n=11) with age 27.8±3.5 and placebo (n=7) with age 34.3±2.3 in a double-blind fashion. They carried out a protocol of Spirulina dietary supplementation (7.5 g/day) of placebo for four weeks and maintained their trainings during this period. A nutritional anamnesis was performed and blood tests were done to determine pre and post levels of creatine kinase (CK), lactic dehydrogenase (LHD), superoxide dismutase (SOD) and malondialdehyde (MDA). The supplemented and placebo groups performed the same volume training, has adequate macronutrients and antioxidant vitamins ingestion before study, as well as initial CK, LDH, SOD and MDA levels. Supplementation did not promote a significant alteration in CK levels on supplemented group (158.4±16.3 for 140.0±16.6 U/l, p>0.05), LDH (420±13.2 for 394.9±27.9 UI/l, p>0.05), MDA (2.8±0.2 for 2.9±0.4 nmol/ml, p>0.05), nor an increase in the SOD (7.3±0.6 for 7.0±0.6 U/mg Hb, p>0.05). We conclude that administration of Spirulina does not interfere in the magnitude of muscle damage nor in antioxidant status of cycling athletes that practice intense training

Clomazone leaching estimate in soil columns using the biological method

The chemical control of weed is a necessary practice in large-scale agriculture. However, when herbicides are used in the wrong way, they can remain into soil for long periods and/or be leached in its profile, and they may even contaminate groundwater. In this research, clomazone leaching in soil samples collected from different Brazilian regions was estimated by biological method. To do so, columns containing soils were used, and samples were collected every 5 cm. After preparing columns and applying a 1,500 g a.i. ha-1 clomazone dose, rain simulation was performed. Sorghum was used in order to detect the herbicide. More than 60% similarity was found for the studied variables; it was chosen to use only data referring to toxicity percentage. Clomazone did not cause reduction in sorghum cultivated in Organosol, thus indicating a strong herbicide sorption in this soil. Increased pH in Oxisol reduced leaching. More rainfall caused increased herbicide leaching in Oxisol (pH 5.1) and Quartzarenic Neosol. The highest leaching occurred in soils with lower pH and lower organic matter content. It is possible to conclude that, in soils with higher organic matter content, clomazone has lower risks of being leached.O controle químico das plantas daninhas é prática consolidada na agricultura em larga escala. No entanto, quando os herbicidas são utilizados da forma incorreta, eles podem permanecer no solo por longos períodos e/ou serem lixiviados no seu perfil, podendo contaminar águas subterrâneas. Nesta pesquisa foi estimada, por método biológico, a lixiviação do clomazone em amostras de solos, coletados em diferentes regiões do Brasil. Para isso, foram usadas colunas contendo os solos, seccionadas de 5 em 5 cm. Após o preparo das colunas e aplicação do clomazone na dose de 1.500 g i.a. ha-1, foi feita a simulação das chuvas (60 e 90 mm). O sorgo foi utilizado para detecção do herbicida. Similaridade superior a 60% foi constatada nas variáveis em estudo, optando-se por utilizar apenas os dados referentes à porcentagem de intoxicação. O clomazone não causou intoxicação ao sorgo cultivado no Organossolo indicando forte sorção do herbicida nesse solo. O aumento do pH do Latossolo Vermelho-Amarelo reduziu a lixiviação. Maior precipitação causou aumento da lixiviação do herbicida no Latossolo Vermelho-Amarelo (pH 5,1) e no Neossolo Quartzarênico. A maior lixiviação ocorreu em solos com menor pH e menor teor de matéria orgânica. Conclui-se que, em solos com maiores teores de matéria orgânica, o clomazone tem menor risco de ser lixiviado

Sorption of Clomazone in Brazilian Soils with Different Physical and Chemical Attributes1

ABSTRACT Knowledge of herbicides sorption by colloids predicts its movement in the soil profile and its effectiveness in controlling weeds and crops poisoning when directly applied to the soil. This knowledge becomes even more important for herbicides which have long persistence in the soil. In this research, clomazone sorption was estimated by the biological method in Brazilian soil samples with different physical and chemical characteristics, cultivated with sugarcane crops. As an indicator of the presence of clomazone in the soil, Sorghum bicolor was used. The data relating to assessments of poisoning and accumulation of dry matter of the plants were subjected to multivariate analysis of similarity among variables. After that, clomazone doses that caused 50% of intoxication in sorghum plants grown (C50) as well as sorption ratio (SR) of the herbicide in different soil types were estimated. There was similarity greater than 80% for data regarding the percentage of intoxication and accumulated dry matter, with the option to use only those related to the first variable. RS and C50 were higher in Organosol and lower in red-yellow Latosol with and without changing the pH. It was concluded that the clomazone dose to be recommended must be differentiated for different soils, since the value of clomazone sorption in the soil is dependent on its attributes, and the organic matter content is of the utmost importance

Application height in herbicides efficiency in bean crops

Inadequate herbicide application can result in failures in weed control and/or poisoning of the crops, resulting in yield losses. In this research were assessed the effects of the sprayer nozzle boom height in the distribution of the spray solution for weed control, influencing intoxication of beans and crop yield. Experiments were conducted in laboratory and field conditions. In laboratory, the performance of flat spray tip TT 11002 was assessed at heights 0.20, 0.30, 0.40 and 0.50 meters with respect to the target surface. In the field the same heights were assessed in applications of herbicides fomesafen, fluazifop-P-butyl and fomesafen + fluazifop-P-butyl. There was an inverse relationship between the height of the spray boom and the coefficients of variation of the patterns. The mixture better efficiency in a tank of fluazifop-P-butyl + fomesafen was obtained with the height of 0.50 m from the target. This treatment resulted in better weed control, lower poisoning of the bean plants and better crop yield rates.Aplicações de herbicidas de forma inadequada podem resultar em falhas no controle das plantas daninhas e/ou intoxicação da cultura, ocasionando em perda de produtividade. Nesta pesquisa foram avaliados os efeitos da altura da barra porta-bicos na distribuição da calda para o controle de plantas daninhas, influenciando a intoxicação do feijoeiro e a produtividade da cultura. Foram realizados experimentos em condições de laboratório e de campo. Em laboratório, avaliou-se o desempenho das pontas de pulverização TT 11002 de jato plano nas alturas de 0,20, 0,30, 0,40 e 0,50 m, em relação à superfície do alvo. No campo, as mesmas alturas foram avaliadas nas aplicações dos herbicidas fomesafen, fluazifop-p-butil e fomesafen + fluazifop-p-butil. Observou-se relação inversa entre a altura da barra e o coeficiente de variação dos perfis. Melhor eficiência da mistura em tanque de fluazifop-p-butil + fomesafen foi obtida com altura de 0,50 m do alvo. Este tratamento resultou em melhor controle das plantas daninhas, menor intoxicação do feijoeiro e melhores índices produtivos da cultura