Evaluation of the initial growth of Jatropha curcas L. under different doses of phosphorus applied to the base

Objetivou-se com este trabalho analisar a influência de diferentes doses de fósforo (P2O5) aplicados na base, no crescimento inicial de Jatropha curcas L. Utilizou-se o delineamento experimental em blocos casualizados, com quatro repetições. Os tratamentos foram constituídos pelas seguintes doses de adubação fosfatada: 0, 50, 100, 150 e 200g planta-1de P2O5 aos 36, 60, 71, 85, 106, 140, 177, 199, 235, 263 dias após o transplantio das mudas. Os parâmetros de crescimento avaliados foram: altura da planta, diâmetro do caule, número de ramos primários e secundários, número de inflorescências, número de frutos, área foliar e produtividade de sementes. As doses de P2O5 influenciaram o crescimento inicial das plantas. Para a maioria das características avaliadas (altura de plantas, número de ramos primários, inflorescências, número de frutos), a dose de 150 g planta-1 foi a que promoveu maior incremento aos 140 DAT. Devido a grande variabilidade genética existente entre plantas, e ao fato de que cientistas da área de melhoramento genético estão trabalhando para o desenvolvimento de cultivares com características agronômicas desejáveis, torna-se necessário a realização de novos estudos com adubação fosfatada para a cultura do pinhão manso.This study aimed to analyze the influence of different doses of phosphorus (P2O5) applied at the base on the initial growth of Jatropha curcas L. The experimental randomized blocks design was used with four replications. The treatments consisted of the following doses of phosphorus fertilization: 0, 50, 100, 150 and 200 g plant-1 of P2O5 at 36, 60, 71, 85, 106, 140, 177, 199, 235 and 263 days after seedlings transplanting. Growth parameters evaluated were as follows: plant height, stem diameter, number of primary and secondary branches, number of inflorescences, fruits number, leaf area and seed yield. The P2O5 levels influenced the early growth of the plants. For most of the evaluated characteristics (plant height, number of primary branches, inflorescences, number of fruits), a dose of 150 g plant-1 was the one that promoted greater increase to 140 DAT. Due to the high genetic variability among plants, and the fact that scientists in the field of genetic improvement are working for the development of cultivars with desirable agronomic characteristics, it is necessary to conduct further studies with phosphate fertilizer for the cultivation of Jatropha

Cana de açúcar no cenário energético tocantinense: influência da adubação química sobre variáveis agroindustriais

A implantação do experimento ocorreu em área cultivada com cana de açúcar pela Usina de produção de açúcar e bioenergia, do Grupo Bunge, no município de Pedro Afonso/TO. O delineamento experimental foi em blocos casualizados, em esquema fatorial 5x2, com quatro repetições, sendo 5 variedades de cana (RB935744, RB867515, RB928064, CTC 15 e SP83-5073) e  2 níveis de adubação ( nível 1 e nível 2), a saber: Nível 01: A adubação utilizada foi 25 kg ha-1 de N, 150 kg ha-1 de P e 100 kg ha-1 de K + 0,3% de Boro e 0,5% de Zn, sem fosfatagem no plantio; Nível 02: Utilizou-se fosfatagem com 220 kg de Superfosfato Triplo, utilizando fosfatos parcialmente solúveis após aração, ao passo que a adubação de plantio foi realizada com 50% a mais da dose, sendo 37 kg ha-1 de N, 225 kg ha-1 de P e 150 kg ha-1 de K+ 0,45% de Boro e 0,75% de Zn. Neste trabalho foram avaliados os seguintes parâmetros de rendimento de campo: O TCH (total de cana por hectare) e o ATR (Açúcares Totais Recuperáveis). Foram avaliados também parâmetros industriais: PCC, Pza, Pol e °Brix. Os resultados demonstraram que não houve diferenças entre os níveis de adubação, portanto a adubação básica é economicamente mais viável. A variedade SP83-5073 apresentou o melhor resultado em toneladas de ATR por hectare

Avaliação da toxicidade de Tiametoxam, Ciproconazol e Paraquat em invertebrados aquáticos

The State of Tocantins is becoming one of the main agricultural centers in Brazil, and the availability of water resources have strengthened agricultural production in the state. Monoculture areas extend mainly along the Araguaia and Tocantins watersheds, which are the two main drainage systems. To achieve high productivity, agricultural crops are highly dependent of pesticide use. As such, agricultural pesticides may reach the aquatic ecosystems through leaching and drift after application, also through the adsorption to biological materials and soil clay particles that are carried to aquatic system by erosion. Consequently, the aquatic ecosystem may be affected due to the toxic effect of these pesticides to aquatic species of different trophic levels. As a result of a field survey of several areas of cultivation in the State of Tocantins, it was found that the insecticide thiamethoxam (TMX), the fungicide cyproconazole (CPZ) and the herbicide paraquat (PQ) are the main pesticides used in many crops, in different areas of cultivation. The aim of this study was to evaluate the toxicity of TMX, CPZ and PQ for freshwater invertebrates, in order to contribute to ecological risk assessment of agricultural pesticides in the ecosystem of the Araguaia-Tocantins watershed. Since information on the lethal and sub-lethal toxicity of the different compounds, particularly for ecologically relevant aquatic species, is crucial for risk assessment of pesticide in aquatic ecosystems, ecotoxicological tests were carried using laboratory tests with two freshwater invertebrates, the dipteran Chironomus riparius and the planarian Dugesia tigrina. Preliminary studies revealed that environmentally relevant concentrations of TMX is did not induced toxicity to D. tigrina and thus, effects of this insecticide were evaluated only using C. riparius (survival, growth, emergence and evaluation of biochemical responses). In the evaluation of CPZ toxicity, the endpoints evaluated in C. riparius included survival, growth and emergence, while in D. tigrina effects were evaluated in terms of survival, regeneration and behavioral responses (locomotion and feeding). For the assessment of PQ toxicity, chronic tests were conducted with C. riparius (growth, emergence and adult weight) and D. tigrina (regeneration, locomotion, and feeding). Our results showed that TMX is highly toxic to C. riparius, since environmentally relevant concentrations affects not only the development rates, but also survival. The CPZ fungicide is moderately toxic to C. riparius (delayed emergence time) and D. tigrina (decreased locomotor activity, feeding activity and delayed regeneration). The herbicide PQ also caused a delay in emergence time and decrease in body weight of C. riparius imagos, as well as reduction in locomotor activity, feeding activity and regeneration of D. tigrina. This study adds ecotoxicological data on the effects of TMX, CPZ and PQ to freshwater invertebrates and suggests that in the long term, these pesticides can potentially disrupt food chains and community structure in freshwater ecosystems. The application of these pesticides namely in the Araguaia-Tocantins watershed should thus be closely monitored in agricultural areas in order to avoid impacts on aquatic ecosystems.O Estado do Tocantins está se tornando um dos principais polos de cultivo agrícola do Brasil e a disponibilidade de recursos hídricos têm fortalecido a produção agrícola no Estado. As áreas de monocultura estendem-se principalmente ao longo da bacia hidrográfica Araguaia e Tocantins, sendo estes os dois principais sistemas de drenagem. Para obtenção de elevadas produtividades, os cultivos agrícolas são altamente dependentes do uso de pesticidas. Adicionalmente, os pesticidas agrícolas podem chegar aos ecossistemas aquáticos através da lixiviação e deriva após a aplicação e também através da adsorção a materiais biológicos e às partículas de argila do solo que são carregados para sistemas aquáticos pelos processos de erosão. Consequentemente, o ecossistema aquático pode ser afetado, devido ao efeito tóxico destes pesticidas para espécies aquáticas de diferentes níveis tróficos. Como resultado de uma pesquisa de campo em várias áreas de cultivo no Estado do Tocantins, verificou-se que o inseticida tiametoxam (TMX), o fungicida ciproconazol (CPZ) e o herbicida Paraquat (PQ) estão entre os principais pesticidas utilizados em diversas culturas e em diferentes áreas de cultivo. O objetivo deste estudo foi avaliar a toxicidade de TMX, CPZ e PQ para invertebrados de água doce, de modo a contribuir para análise de risco ecológico de pesticidas agrícolas no ecossistema da bacia hidrográfica Araguaia-Tocantins. Como a informação sobre a toxicidade letal e sub-letal de diferentes compostos, particularmente para espécies aquáticas ecologicamente relevantes, é crucial para a avaliação dos riscos de pesticidas em ecossistemas aquáticos, foram realizados ensaios ecotoxicológicos, utilizando ensaios laboratoriais com dois invertebrados de água doce, o díptero Chironomus riparius e a planária Dugesia tigrina. Estudos preliminares revelaram que TMX não é tóxico para D. tigrina em concentrações ambientalmente relevantes, logo a toxicidade deste pesticida foi avaliada apenas sobre C. riparius (sobrevivência, crescimento, emergência e avaliação de respostas bioquímicas). Na avaliação da toxicidade de CPZ, os parâmetros avaliados em C. riparius incluem sobrevivência, crescimento e emergência, enquanto que em D. tigrina foram avaliados sobrevivência, regeneração e respostas comportamentais (locomoção e alimentação). Para avaliação da toxicidade de PQ, ensaios crônicos foram conduzidos com C. riparius (avaliação de crescimento, emergência e peso de mosquitos adultos) e D. tigrina (avaliação de regeneração, locomoção e alimentação). Os resultados evidenciaram que TMX é altamente tóxico para C. riparius, uma vez que concentrações ambientalmente relevantes afetam não só o desenvolvimento do organismo, mas também a sobrevivência. O fungicida CPZ é moderadamente tóxico para C. riparius (atraso no tempo à emergência) e D. tigrina (decréscimo da atividade locomotora, atividade alimentar e capacidade de regeneração). O herbicida PQ também provocou atraso no tempo à emergência, além de diminuição do tamanho dos adultos de C. riparius, bem como redução na atividade locomotora, atividade alimentar e capacidade de regeneração de D. tigrina. Este estudo acrescenta dados ecotoxicológicos sobre os efeitos de TMX, CPZ e PQ sobre invertebrados de água doce e sugere que, em longo prazo, estes pesticidas podem potencialmente perturbar cadeias alimentares e estrutura da comunidade nos ecossistemas de água doce. A aplicação destes pesticidas em particular na bacia hidrográfica Araguaia-Tocantins deve ser cuidadosamente monitorada nas áreas agrícolas de modo evitar impactos sobre os ecossistemas aquáticos

Behavioral Parameters of Planarians (Girardia tigrina) as Fast Screening, Integrative and Cumulative Biomarkers of Environmental Contamination: Preliminary Results

The present study aims to use behavioral responses of the freshwater planarian Girardia tigrina to assess the impact of anthropogenic activities on the aquatic ecosystem of the watershed Araguaia-Tocantins (Tocantins, Brazil). Behavioral responses are integrative and cumulative tools that reflect changes in energy allocation in organisms. Thus, feeding rate and locomotion velocity (pLMV) were determined to assess the effects induced by the laboratory exposure of adult planarians to water samples collected in the region of Tocantins-Araguaia, identifying the sampling points affected by contaminants. Furthermore, physicochemical and microbiological parameters, as well as the presence of inorganic compounds (dissolved aluminum, total barium, total chloride, dissolved iron, total fluoride, total manganese, nitrates, nitric nitrogen, total sulfate, total zinc) and surfactants, were determined on each specific sampling point. The behavioral biomarkers (feeding rate and pLMV) of the freshwater planarians were significantly decreased when organisms were exposed to water samples from four municipalities (Formoso do Araguaia, Lagoa da Confusão, Gurupi and Porto Nacional), sites of the Tocantins-Araguaia hydrographic region—TAHR. Both behavioral biomarkers decreased up to ~37–39% compared to organisms in ASTM medium only. Our results showed that these behavioral biomarkers can be used for fast screening monitoring of environmental samples of freshwater ecosystems, since a decrease in feeding rate and locomotor activity was observed in sites impacted by anthropogenic activities. However, the absence of effects observed in some sampling points does not represent the absence of contamination, since several other classes of contaminants were not determined. In these negative results, the absence of deleterious effects on behavioral biomarkers might only be indicative that the potential presence of contaminants on such sites does not significantly affect the performance of planarians. This fast screening approach seems to be useful to determine contaminated sites in freshwater ecosystems for biomonitoring purposes. This knowledge will help to develop biomonitoring programs and to decide appropriate sampling sites and analysis

What does not kill it makes it stronger! The tolerance of the F1 larvae of Chironomus xanthus to a neonicotinoid insecticide formulation

Thiamethoxam (TMX) is a systemic neonicotinoid that acts as a partial agonist of the nicotinic acetylcholine receptors (nAChRs). However, target species have shown resistance to formulations based on such neonicotinoids, which can also be expected for non-target insects. This research aimed to study the effects of a formulation based on TMX [Cruiser® 350 FS (CRZ)] on the life traits of Chironomus xanthus filial generation (F1) and compare it with the parental generation (P). Environmentally relevant concentrations of CRZ significantly decreased larvae growth P generation , also slowing and decreasing their emergence. Larvae of the F1 generation were less sensitive than their parents, suggesting that the progeny were able to thrive and perform basic physiological functions better than the parental generation. Our results highlight that insect resistance to neonicotinoids may be associated with the better performance of the filial generation, which is related to the change in affinities of the active ingredient for the sub-units constituting the nAChRs subtypes of F1 organisms, inherited from P organisms that were able to survive and reproduce. Moreover, further studies using biochemical and omics tools should be performed to disentangle the specific changes occurring at the nAChRs throughout insect development

Low concentrations of glyphosate-based herbicide affects the development of chironomus xanthus

Glyphosate is an herbicide commonly used worldwide for weed control and generally applied as part of a formulated product, such as Roundup. Contamination of surface water by glyphosate-based herbicides can cause deleterious effects in organisms, mainly in aquatic systems near to intensive agricultural areas (e.g., transgenic soybean crops). Given the lack of toxicological information concerning effects of glyphosate-based herbicides on tropical aquatic ecosystems, we aimed to evaluate the lethal and sub-lethal effects of Roundup Original® on the dipteran Chironomus xanthus. The endpoints evaluated included survival, growth, and emergence. The results showed that the 48 h LC50 for glyphosate to C. xanthus was 251.5 mg a.e./L. Larval growth of C. xanthus was reduced under glyphosate exposure (LOEC for body length = 12.06 mg/L; LOEC for head capsule width = 0.49 mg/L). No effects were observed in terms of cumulative percentage of imagoes emergence. However, low concentrations of glyphosate caused delayed emergence of females (at 1.53 mg/L) and induced fast emergence of males (at 0.49 mg/L), compared to control treatment. The deleterious effects of environmental relevant concentrations of glyphosate (0.7 mg/L) observed in terms of C. xanthus growth and development suggest that glyphosate-based herbicides can have negative consequences for aquatic non-target invertebrates such as Chironomus. Multigerational assays are needed to assess the long term effects of glyphosate on C. xanthus populations. Finally, our study adds ecotoxicological data on the effects of glyphosate-based herbicides on tropical freshwater invertebrates