Sample size for estimation of averages of agronomic traits in cassava seedlings

O método de multiplicação rápida melhora o uso de material de propagação. No entanto, melhorar o gerenciamento e as técnicas experimentais é crucial para avaliar a produção e a qualidade da planta. Este estudo calculou o tamanho da amostra para estimar médias de caracteres agronômicos em mudas de mandioca originárias de estacas de caule com um número diferente de folhas e diâmetros diferentes. Um total de 600 mudas (cada uma com duas gemas) com um diâmetro de 15,00 a 19,99 mm (N = 300) ou 20,00 a 25,00 mm (N = 300) da cultivar Apronta Mesa foram plantadas em diferentes épocas de cultivo (julho, agosto, Setembro e outubro). Em cada estação de plantio (22 de setembro, 7 de outubro, 19 de outubro e 25 de novembro), 300 estacas, com três a cinco ou até mais de cinco folhas visíveis, foram coletadas. As seguintes estatísticas foram analisadas: mínimo, máximo, intervalo, média, mediana, variação, desvio padrão e coeficiente de variação. O tamanho da amostra foi determinado por reamostragem usando 2.000 reamostragens, com substituição, e foi definido pelo número de plantas a partir das quais o intervalo de confiança de 95% foi de 10%, 15% e 20% da estimativa média. O uso de estacas de caule com diâmetro superior a 20 mm e com mais de cinco folhas foi adequado para a produção de mudas de mandioca. Independentemente da faixa no diâmetro de corte e número de folhas, 87 plantas foram suficientes para estimar as médias das características quando a faixa do intervalo de confiança foi de 20% da estimativa média. e 20% da estimativa média. O uso de estacas de caule com diâmetro superior a 20 mm e com mais de cinco folhas foi adequado para a produção de mudas de mandioca. Independentemente da faixa no diâmetro de corte e número de folhas, 87 plantas foram suficientes para estimar as médias das características quando a faixa do intervalo de confiança foi de 20% da estimativa média. e 20% da estimativa média. O uso de estacas de caule com diâmetro superior a 20 mm e com mais de cinco folhas foi adequado para a produção de mudas de mandioca. Independentemente da faixa no diâmetro de corte e número de folhas, 87 plantas foram suficientes para estimar as médias das características quando a faixa do intervalo de confiança foi de 20% da estimativa média

Fungicides application in corn disease control and mycotoxin accumulation in grain

In Brazil, corn planted area increased by 30%. Therefore, there was also an increase in the incidence of pathogens in the crop. The objective of this work was to evaluate the influence of fungicide applications on corn crops in the different growth stages for the control of the diseases and its effect on the occurrence of mycotoxins in the grain. The experiment was carried out in the 2017/2018 summer crop, in the municipality of Cruz Alta, state of Rio Grande do Sul/BR. This study used P 1630 hybrid, in a randomized block design with eight treatments (control, V8, PT, V4 + V8, V4 + V8 + PT, V8 + PT, V8 + PT + 15, PT + 15) and three replicates. The fungicide fluxapiroxade + pyraclostrobin + epoxiconazole at the dose of 1.0 L/ha-1 was used. The diseases that affected the crop were the white spot and helmintosporiosis, therefore, reducing the incidence of diseases. Also the highest yields were obtained where the applications started at the phenological stage V4 and V8. The levels of mycotoxins detected in this work remained within the limits of the legislation, with a significant reduction in the accumulation of fumonisin and aflatoxin with fungicide applications

Herbicide resistance technologies in soybean cultivars

The objective of this work was to carry out a technical analysis of the biotechnologies that confer resistance to herbicides in soybeans. Two experiments were carried out (I and II) in the agricultural years 2016/17 and 2017/18, using a randomized block design with six  and four  replicates. In experiment I, two forms of management in weed control were evaluated for each technology studied (Roundup Ready® and Liberty Link®) and for conventional soybeans, as well as grain yield. In experiment II, the efficiency of using different herbicides to control voluntary soybeans (with and without technology) was evaluated. The pre-emergent herbicides in both managements proposed for the cultivars controlled the weeds from the emergence of the soybean crop to the application of the post-emergent herbicides in both crops. Likewise, all post-emergent herbicides showed weed control above 90% at 14 and 28 days after application. In the evaluation of the chemical control of Garra IPRO voluntary soybean, the herbicide 2,4-D stood out among the others for being more efficient in both agricultural years (above 90%). The herbicides glyphosate, 2,4-D and metsulfuron-methyl are the most effective in controlling voluntary soybean cultivars BRS 284 and CZ16B39LL

Use of isolated fungicides for the control of Phakopsora pachyrhizi in soybean

The occurrence of diseases in soybean crop has negatively affected its development and caused significant losses in productivity. Among the diseases, Asian rust caused by the fungus Phakopsora pachyrhizi Sydow stands out because of its high severity. As a way of controlling, chemical fungicides is a tool used to mitigate the damage. The objective of this work was to evaluate the efficiency of different isolated fungicides in the control of Asian rust. The experiment was carried out in the experimental area of ​​the University of Cruz Alta in the state of Rio Grande do Sul with a randomized block design and four replications. The cultivar used was BMX Ativa, and the fungicide applications occurred before the interline closure and later with 15 days of interval between applications. The fungicides tested in the experiment were: metominostrobin + tebuconazole, piraclostrobin + fluxpyroxade, picoxystrobin + cyproconazole, Azoxystrobin + benzovindiflupir, picoxystrobin + benzovindiflupir, Trifloxystrobin + protioconazole, Pyraclostrobin + epoxiconazole + fluxpyroxade, Bixafen + protioconazole + Trifloxystrobin, Mancozebe + picoxystrobin + tebuconazole and control. The variables analyzed were yield kg ha-1, weight of one thousand seeds and disease severity. The fungicides Mancozebe + picoxystrobin + tebuconazole and bixafen + protioconazole + trifloxystrobin showed the highest yield, one thousand grain weight and lower severity of Asian soybean rust

BIOESTIMULANTE APLICADO NA SEMENTE E VIA FOLIAR NA PRODUÇÃO DE REPOLHO

O objetivo foi avaliar o efeito de doses do bioestimulante ácido 4-indol-3-ilbutírico + ácido giberélico + cinetina no crescimento, desenvolvimento e produtividade do repolho hibrido cultivar Musashi. Conduziu-se dois experimentos com doses de bioestimulante (0, 3, 5, 7 e 9 ml) no delineamento inteiramente casualizado com 5 repetições. O bioestimulante ácido 4-indol-3-ilbutírico + ácido giberélico + cinetina não influencia o crescimento, o desenvolvimento, e a produtividade de repolho

Seed cassava cuttings production: alternative use of growing substrates

Este experimento foi realizado para melhorar a técnica de propagação rápida em diferentes substratos aplicados às culturas de mandioca, a fim de multiplicar genótipos tradicionais com base em características selecionadas. A primeira etapa do estudo foi realizada em setembro de 2016 em camas ao ar livre cobertas com plástico transparente. Foram testados quatro genótipos tradicionais de mandioca e uma cultivar de mandioca (Fepagro RS13). Medições das temperaturas do ar e do solo foram realizadas durante todo o experimento até que mais da metade dos adubos plantados foram germinados. As medições pararam quando a maioria das plântulas brotou. A segunda etapa do experimento foi realizada em novembro de 2016 (corte em diferentes substratos), quando as plantas apresentaram quatro folhas totalmente expandidas. Os brotos foram cortados e transplantados para recipientes individuais com quatro substratos diferentes (água, areia, solo e substrato comercial). Após o transplante, as mudas foram armazenadas em casa de vegetação, sob temperatura e irrigação controladas. Folhas, caule e raízes secas e massas frescas e o tamanho das três raízes mais longas por planta foram avaliados 40 dias após o início do experimento. As cultivares Fepagro RS13 e SJ13 se destacaram entre as variedades avaliadas, por apresentarem bom potencial para multiplicação rápida. Substratos comerciais podem ser uma alternativa para propagação rápida. porque eles apresentaram bom potencial para multiplicação rápida. Substratos comerciais podem ser uma alternativa para propagação rápida. porque eles apresentaram bom potencial para multiplicação rápida. Substratos comerciais podem ser uma alternativa para propagação rápida

Nonlinear models. An approach to model irrigated and non-irrigated common bean (Phaseolus vulgaris L.) growth

Common beans reduce their development and productivity when facing soil water deficit. Comprehension about growth response under this condition can be a tool for cultivar selection and escape from scarcity periods. Therefore, the objective was to characterize bean growth in different water conditions using logistic and chanter models. Two experiments (crop season= EI and fallow season = EII) were carried out in Santa Maria, RS, Brazil in a bifactorial scheme (cultivars: Triunfo, Garapiá, FC104; water condition: irrigated, not irrigated) in a completely randomized design. Fortnightly evaluations of height, number of nodes, stem diameter, root length, aerial part, roots, and nodules dry matter were carried out. The data were adjusted according to the accumulated thermal sum by the logistic and chanter models. From the results, it is noted that there was a dissimilar performance between water conditions, cultivars, and experiments. The best adjustment occurred for stem diameter, node number, and aerial part dry matter. Between models, the logistic is the most suitable to describe common bean growth

Biomass and nutrient cycling by winter cover crops

ABSTRACT Cover crops are of fundamental importance for the sustainability of the no-tillage system, to ensure soil coverage and to provide benefits for the subsequent crop. The objective of this study was to evaluate the production of biomass and the content and accumulation of nutrients by winter cover crops. The experimental design used in the experiment was a randomized complete block with four replications and six treatments: oilseed radish, vetch, black oats, vetch + black oats, vetch + oilseed radish and fallow. Black oat, oilseed radish in single cultivation and black oat + vetch and vetch + oilseed radish intercroppings showed higher dry matter production. Vetch + oilseed radish intercropping demonstrates higher performance regarding cycling of nutrients, with higher accumulations of N, P, K, Ca, Mg, S, Cu, Zn, Fe, Na and B

Population survey of phytonematodes in soybean crop in the Middle Plateau region in Rio Grande do Sul

The objective of this study was to determine and quantify the main phytonematodes found in soybean crops in the state of Rio Grande do Sul and to estimate the population level where they are found. Therefore, samples of soil and soybean roots were received from 154 municipalities of the Middle Plateau region  of Rio Grande do Sul, from 2014 to 2016. After receiving and registering the samples, nematodes were extracted, identified and quantified in each sample. Through these data, it was determined the absolute frequency (AF), relative frequency (RF), absolute density (AD) and relative density (DR) of each nematode genus as well as their average population level in the municipalities. The main genera found in the study were Meloidogyne (found in 7.5% of the samples), Pratylenchus (6.2%), Heterodera (4.3%), Rotylenchulus (1.6%) and Helicotylenchus (22.9%). The species Meloidogyne species was not identified, but for Pratylenchus two species were identified, P. brachyurus and P. zeae. Besides these two genera, others were found, among them Heterodera glycines, Rotylenchulus reniformis and Helicotylenchus dihystera. The most frequently found nematode was H. dihystera, and in relation to population level, Meloidogyne spp. stands out for showing the highest levels in the municipalities in the three years of evaluation