Leandro Homrich Lorentz

Spatial distribution of sunflower cultivars and the relationship between growth features

This work aimed to evaluate the performance of six genotypes of sunflower under two spatial distributions between plant rows, and verify the cause effect relation between growth features. The experiment was carried at experimental area of Federal Technological University of Parana (Campus Dois Vizinhos), evaluating six sunflower cultivars and two spatial distributions (40 and 80 cm between rows), remaining the total plant population similar, 55.000 plants by hectare. It was performed a path analysis, identifying the features that have most influence on sunflower grain yield and one hundred grain weight, also multiple regression analysis was used to estimate the equation for grain yield and one hundred grain weight. It was verified that sunflower genotypes do not present different performances under the evaluated spatial distributions, however, the genotypes showed to be significantly different for most of the features evaluated. Direct effect under grain yield was observed for the features number of plants and stem diameter at 15 days, while the indirect effects were observed for plant stature via stem diameter, both at 15 days. For the feature one hundred grain weight it was verified that only plant stature at 90 days promoted a direct effect, but negative.

Effect of neighborhood and plot size on experiments with multiple-harvest oleraceous crops

The objective of this work was to determine the efficiency of the Papadakis method on the quality evaluation of experiments with multiple-harvest oleraceous crops, and on the estimate of the covariate and the ideal plot size. Data from nine uniformity trials (five with bean pod, two with zucchini, and two with sweet pepper) and from one experiment with treatments (with sweet pepper) were used. Through the uniformity trials, the best way to calculate the covariate was defined and the optimal plot size was calculated. In the experiment with treatments, analyses of variance and covariance were performed, in which the covariate was calculated by the Papadakis method, and experimental precision was evaluated based on four statistics. The use of analysis of covariance with the covariate obtained by the Papadakis method increases the quality of experiments with multiple-harvest oleraceous crops and allows the use of smaller plot sizes. The best covariate is the one that considers a neighboring plot of each side of the reference plot.

Proposta de método para estimação de tamanho de parcela para culturas agrícolas

Dentre as formas reconhecidas para reducao do erro experimental, destaca-se o tamanho otimo da parcela experimental para aplicacao dos tratamentos, existindo varios metodos para sua estimacao, baseados em diferentes principios. O objetivo deste trabalho e propor um metodo alternativo para a estimacao do tamanho otimo de parcela, para culturas agricolas, compara-lo com metodos classicos para esse fim e identificar com quais parâmetros seus resultados estao correlacionados. Realizou-se a validacao dos resultados, utilizando-se dados de quatro experimentos com plantas de pimentao, em que se avaliou a producao de frutos, acumulada nas varias colheitas, cultivado em estufa com cobertura plastica. Os resultados obtidos pelo metodo proposto, denominado Metodo da Maxima Distância, sao coerentes, mas fracamente associados aos resultados observados pelos demais metodos classicos. O tamanho otimo da parcela, estimado pelo Metodo da Maxima Distância, e fortemente influenciado pelo indice de heterogeneidade da producao, que mede a correlacao entre as producoes de parcelas contiguas. Ha, ainda, as caracteristicas de ser de facil aplicacao, praticamente invariavel a acumulacao da producao em diversas colheitas, adequando-se para culturas com duas ou mais colheitas nas mesmas plantas, como em experimentos com culturas olericolas ou forrageiras.

Mechanism of Rhinella icterica (Spix, 1824) Toad Poisoning using in vitro Neurobiological Preparations

HighlightsRhinella icterica poison induces neuromuscular blockade.Rhinella icterica poison induces central neurotoxicity.Rhinella icterica poison presents bufalin.The poison mechanisms relay on biochemical and ionic channels interactions. ABSTRACT The biological activity of Rhinella icterica toxic secretion (RITS) was evaluated on chick neuromuscular junctions, rat heartśs tissue and mice hippocampal slices. At chick biventer cervicis preparation, RITS (5, 10 and 20 &mgr;g/mL) produced a concentration‐independent irreversible neuromuscular blockade, which was preceded by a transitory increase of muscle twitch tension with the lowest concentration, in 120 min recordings. In this set of experiments, RITS incubation partially prevented the curare neuromuscular blockade. The assessment of chick biventer cervicis muscle acetylcholinesterase (AChE) in the presence of RITS showed a significant inhibition of the enzyme, similarly to neostigmine. The incubation of muscles with digoxin or ouabain mimicked the poison activity by increasing the amplitude of the twitches followed by a progressive depression of the muscle strength. In addition, RITS demonstrated a digitalic‐like activity, by inhibiting significantly the cardiac Na+, K+‐ATPase. When the central nervous system was accessed, RITS induced an increase in the cell viability, in the lowest concentration. In addition, the poison protected slices subject to oxygen/glucose deprivation. Altogether, these data indicate that the poisonous extract of R. icterica is able to interfere with peripheral and central neurotransmission, probably due to a direct interaction with AChE, calcium channels and Na+, K+‐ATPase. A further investigation upon the poison toxic components will unveil the components involved in such a pharmacological activity and the potential biotechnological application of this poison.

Genetic profile of Holstein and Jersey dairy bull lines available in Brazil

As racas de bovinos de leite Holandesa e Jersey estao entre as mais prevalentes no Brasil. Para avaliar as diferencas entre as PTAs (habilidades de transmissao preditas) destas racas e suas linhagens, foram coletadas informacoes de 385 touros Holandes e 82 touros Jersey disponibilizados por nove empresas comercializadoras de semen no Brasil. Tres diferentes linhagens de cada raca foram encontradas. O metodo dos modelos lineares generalizados foi utilizado para a comparacao entre linhagens e entre racas. As duas linhagens da raca Holandesa mais prevalentes apresentaram as maiores PTAs medias para producao de leite (1.061,04 libras e 975,32 libras) e as menores PTAs para a porcentagem de solidos no leite (de -0,05% a -0,0003%) (P<0.05). Estes resultados sugerem a oferta de touros no mercado nacional que sao capazes principalmente de aumentar a producao de leite. A raca Jersey apresentou um coeficiente de endogamia mais elevado (6,62%) que o da raca Holandesa (5,14%) (P<0.05). Embora a raca Holandesa tenha apresentado maiores PTAs para producao de leite e as menores PTAs para a porcentagem de solidos no leite, a vida produtiva da raca Jersey apresentou-se mais longa (1,17 meses) (P<0.05) que a da raca Holandesa (0,40 meses). Houve uma importante variabilidade do material genetico disponivel, permitindo a escolha do semen mais adequado para cada sistema de producao. Faz-se necessario conhecer o perfil genetico dos touros disponibilizados para inseminacao artificial no Brasil, com vistas ao conhecimento e direcionamento do padrao genetico dos bovinos leiteiros no pais.

Relações entre medidas de qualidade de lotes de sementes de arroz

A qualidade de um lote de sementes nao e uma grandeza mensuravel diretamente. E preciso a realizacao de diversos testes, cujos resultados conjuntamente permitem concluir quanto a sua qualidade. Dessa forma, pode haver a realizacao de testes redundantes, altamente relacionados entre si, sem que acrescente em poder de discriminacao dos lotes e levando a desperdicio de tempo e recursos para obtencao de uma recomendacao. O objetivo desta pesquisa e identificar o conjunto de testes nao correlacionados entre si para avaliar a qualidade de lotes de sementes de arroz. Assim, submeteu-se 67 lotes de sementes de arroz de diferentes procedencias a nove testes para avaliacao da sua qualidade fisiologica, incluindo variaveis morfologicas, de vigor e germinacao. Estimou-se a matriz de correlacao entre as nove variaveis e aplicou-se a analise fatorial, optando-se pelo numero de fatores cuja variância acumulada fosse superior a 70%. Observou-se que a utilizacao de tres fatores foi suficiente para acumular 80,4% da variância total e concluiu-se que a massa verde das plântulas, a percentagem de germinacao e o comprimento da parte aerea, avaliadas aos 14 dias apos a semeadura ou apenas o indice de velocidade de germinacao e emergencia no solo sao suficientes para a identificacao da qualidade dos lotes de sementes de arroz.

Genetic progress in sunflower crop in Rio Grande do Sul State, Brazil

The sunflower has adaptability to growing regions with different climatic and soil characteristics, showing drought tolerance and high-quality oil production. The State of Rio Grande do Sul is the third largest sunflower producer in Brazil, with research related to the sunflower breeding initiated after the decade of 1950. The aim of this study was to evaluate the genetic progress for grain yield, oil content, and oil yield of sunflower (Helianthus annuus L.) in the State of Rio Grande do Sul. Data of grain yield, oil content, and oil yield obtained from 58 sunflower cultivar yield trials in 19 municipalities in Rio Grande do Sul during the period from 2005 to 2014 were used. Genetic progress was studied according to the methodology proposed by Vencovsky and data from sunflower cultivar yield trials were used. Annual genetic progress of sunflower during the period of 10 years (2005-2014) was 132.46 kg⋅ha-1⋅year-1 for grain yield, -0.17%/year for oil content, and 48.11 kg⋅ha-1⋅year-1 for oil yield. The sunflower-breeding programs in the State of Rio Grande do Sul were efficient for the traits grain yield and oil yield and presented no efficiency for oil content.

Effects of different cultivation systems in leaf traits and herbivory damage in Ilex paraguariensis (Aquifoliaceae)

Different environmental conditions are crucial to determine many attributes in plants by selective pressures. Plant traits and ecological interactions may present variation in outputs in these distinctive selection scenarios. In south Brazil, yerba mate (Ilex paraguariensis A. St.-Hil.) has been cultivated in monoculture and in consortium systems, differing significantly in lightning intensity and associated plant richness. In this study, three areas of both cultivation systems were monitored to verify the plant outputs in leaf area and herbivory damage. Our results showed that consortium system cultivation presents higher values of leaf area and higher damage by herbivory. Higher leaf area in consortium system corresponds to numerous studies and corroborates the phenotypic plasticity expected for Ilex paraguariensis. On the other hand, the higher leaf damage opposed the hypothesis that greater plant richness should promote the best herbivory control by natural enemies. Despite the higher foliar loss plants cultivated under consortium system present adequate leaf area to farmers. Beside species richness, other plant community traits play important role in mitigation of herbivory.

Tamanho e forma da unidade amostral para quantificação da serapilheira em fragmento de Floresta Estacional Subtropical

Para o estudo do ciclo de nutrientes em uma floresta, e necessaria a estimacao precisa da quantidade de serapilheira depositada e de suas fracoes. Entre as formas reconhecidas para minimizar a variabilidade entre amostras esta o uso do tamanho otimo de unidades amostrais para a coleta da serapilheira. Entretanto, existem poucas recomendacoes nesse sentido, o que gera variacao no tamanho da unidade amostral utilizada em experimentos similares. Assim, o objetivo deste trabalho foi determinar o tamanho e a forma otimos da unidade amostral para quantificacao de serapilheira em Floresta Estacional Subtropical. Para isso, foram alocadas, aleatoriamente, na area cinco parcelas de dimensoes 3,0 x 2,0 m em cada uma das quatro estacoes do ano, subdivididas em 96 unidades basicas de 0,25 x 0,25 m. Em cada unidade basica foi coletada toda a materia orgânica acima do solo, sendo esta separada nas fracoes folhas, galhos finos, residuo. A estimativa do tamanho otimo da unidade basica foi obtida por dois metodos distintos. Observou-se que o coeficiente de variacao diminui a medida que aumenta o tamanho da unidade amostral; ha diferencas na variabilidade da producao de serapilheira entre as parcelas na mesma estacao de coleta; unidades amostrais retangulares sao mais homogeneas entre si que as quadradas; recomenda-se a utilizacao de unidades amostrais de 0,40 m2 (1,5 m x 0,25 m) para a coleta de serapilheira em fragmento de Floresta Estacional Subtropical.