Inheritance of Nitrogen Use Efficiency in Inbred Progenies of Tropical Maize Based on Multivariate Diallel Analysis

The objective of our study was to characterize and determine the patterns of genetic control in relation to tolerance and efficiency of nitrogen use by means of a complete diallel cross involving contrasting inbred progenies of tropical maize based on a univariate approach within the perspective of a multivariate mixed model. Eleven progenies, previously classified regarding the tolerance and responsiveness to nitrogen, were crossed in a complete diallel cross. Fifty-five hybrids were obtained. The hybrids and the progenies were evaluated at two different nitrogen levels, in two locations. The grain yield was measured as well as its yield components. The heritability values between the higher and lower nitrogen input environment did not differ among themselves. It was observed that the general combining ability values were similar for both approaches univariate and multivariate, when it was analyzed within each location and nitrogen level. The estimate of variance of the specific combining ability was higher than general combining ability estimate and the ratio between them was 0.54. The univariate and multivariate approaches are equivalent in experiments with good precision and high heritability. The nonadditive genetic effects exhibit greater quantities than the additive genetic effects for the genetic control of nitrogen use efficiency

Ingestive Behavior and Nutritional and Physiological Parameters of Sheep Fed Diets Based on Cashew Byproduct

Objective of this study was to evaluate the ingestive behavior, feed efficiency, and nutritional and physiological parameters of sheep that were fed diets based on byproducts from the processing of cashew. The experiment was conducted in a completely randomized design with a 4 × 2 factorial arrangement with four levels of inclusion (6 %, 11 %, 16 %, and 21 % of cashew byproduct) and two forms of processing—with chemical treatment (CT) and without chemical treatment (NCT). The interaction levels of inclusion of the byproduct of cashew versus chemical treatments was not (P>0.05) for the dry matter intake, consumption of organic matter. No effect was observed (P>0.05) for the intake of dry matter in function of the type of chemical treatment used in the byproduct of cashew. There was no effect of interaction (P0.05). The inclusion of the byproduct of cashew did not influence the behavioral parameters, intake and digestibility of the diets of sheep, being recommended to use up to the level of 21%

Genetic progress with reciprocal recurrent selection for interpopulation hybrids of maize

O objetivo deste trabalho foi avaliar o progresso genético na obtenção de híbridos interpopulacionais com a seleção recorrente recíproca. Na safra 2005/2006, foram avaliados os híbridos interpopulacionais de milho (Zea mays) originados de três ciclos de seleção (0, 1 e 2) iniciados em 2003, os híbridos simples parentais e o híbrido duplo de F1, em blocos ao acaso com cinco repetições, em dois locais. Na safra seguinte, somente os híbridos interpopulacionais dos ciclos 0 e 2 foram avaliados nas mesmas condições, com 40 repetições por local. O híbrido interpopulacional apresentou desempenho equivalente ao do melhor híbrido parental simples em poucos ciclos seletivos. As estimativas do progresso genético por ciclo foram de 7,9% (ou 0,7 Mg ha-1) para produtividade de espigas despalhadas e de 3,5% para prolificidade. É possível inferir que a seleção recorrente recíproca é eficiente em elevar a produção de híbridos interpopulacionais obtidos a partir de populações F2 de híbridos simples de milho.The objective of this work was to evaluate the genetic progress obtained in interpopulation hybrids with the reciprocal recurrent selection. During the 2005/2006 planting season, maize (Zea mays) interpopulation crosses from three selection cycles (0, 1 and 2) initiated in 2003, single-cross parental hybrids and the double-cross F1 hybrid were evaluated in randomized blocks with five replicates, at two locations. In the next planting season, only interpopulational hybrids from cycles 0 and 2 were evaluated under the same conditions, with 40 replicates per location. The interpopulation hybrid had a yield performance equivalent to that of the best single-cross parent in few selection cycles. The estimates of genetic progress per cycle were of 7.9% (or 0.7 Mg ha-1) for unhusked ear yield and of 3.5% for prolificacy. It is possible to infer that the reciprocal recurrent selection effectively improves the yield of interpopulational hybrids obtained from F2 generations of single-cross maize hybrids

Influência dos sistemas de cultivo sobre a emissão de voláteis na alfacicultura / Influence of cropping systems on volatile emissions in the lettuce crop

Os metabólitos secundários sintetizados por alguns grupos de vegetais são responsáveis por aumentarem suas chances de sobrevivência pois influenciam diretamente nas relações das cadeias tritróficas atraindo, repelindo ou matando alguns insetos de forma direta ou indireta. Os principais grupos de metabólitos secundários são os compostos fenólicos, terpênicos e esteróides, e os alcalóides. Esses compostos apresentam ações antivirais, antifúngicas, defesa contra pragas e inibição a competição de outras espécies de plantas. Dessa forma é de suma importância o reconhecimento desses compostos orgânicos voláteis (COVs) assim como a compreensão de como os fatores abióticos tais como as mudanças ambientais e estresses podem influenciar no tipo de volátil produzido pelo vegetal. O presente estudo teve como objetivo avaliar se há diferença entre os compostos voláteis produzidos pela alface no manejo orgânico e no convencional. Os COVs emitidos pela alface foram coletados utilizando a técnica de headspace. Os COVs obtidos foram injetados em um sistema de cromatografia gasosa acoplada a um espectrômetro de massa (GC/MS) QP5050A. O sistema orgânico apresentou dois voláteis (3-metil-ciclopent-2-en-1-ona e 4-Hidroxibenzoato de etila) que foram ausentes no sistema convencional. Já o convencional apresentou três compostos (4-etilacetofenona, Benzofenona, Nonacosano) ausentes no sistema orgânico. Esses resultados sugerem que fatores abióticos como o tipo de manejo escolhido podem afetar as vias biossintéticas das plantas e influenciar na produção de determinados voláteis. O estudo da emissão de voláteis poderá auxiliar na escolha das espécies a serem cultivadas em uma mesma área possibilitando um benefício para elas em relação a redução de pragas e o aumento da presença de inimigos naturais e de polinizadores

ANÁLISE GEOMORFOLÓGICA E PROCESSOS EROSIVOS ACELERADOS NA BACIA HIDROGRÁFICA DO RIO TIBIRI, ILHA DO MARANHÃO

A Geomorfologia tem como finalidade analisar as formas de relevo e os processos ocorrentes, sendo uma ciência fundamental para auxiliar a gestão e o planejamento urbano e ambiental, já que a ocupação inadequada de ambientes urbanos tem aumentado progressivamente. Assim, o objetivo desta pesquisa é analisar os fatores geoambientais, com ênfase à geomorfologia, em relação aos processos erosivos acelerados na bacia do rio Tibiri, localizada na Ilha do Maranhão, a partir da elaboração de mapeamento geomorfológico subsidiado na classificação taxonômica de Ross (1992). As formas de relevo encontradas na bacia são equivalentes ao terceiro até o sexto táxon, sendo o último correspondente às formas erosivas, que recebem influência dos táxons antecessores e suas morfologias. Por meio do levantamento bibliográfico e cartográfico, trabalhos de campo e de gabinete, foram analisados processos erosivos em alto estágio de evolução, como as voçorocas Vila Santana, Matadouro, Cemitério e Cemitério II, além do processo de urbanização com a fixação de residências em localidades frágeis do ponto de vista ambiental. Portanto, percebe-se a necessidade de planejar a ocupação da área, considerando a intensidade dos processos morfodinâmicos e a premência de técnicas para a prevenção e sua consequente conservação.

Larvicidal Activity against Aedes aegypti

This study investigated the biological activities of five benthic marine algae collected from Northeastern Region of Brazil. The tested activities included larvicidal activity against Aedes aegypti, molluscicidal activity against Biomphalaria glabrata, and toxicity against Artemia salina. Extracts of Ulva lactuca (Chlorophyta), Padina gymnospora, Sargassum vulgare (Phaeophyta), Hypnea musciformis, and Digenea simplex (Rhodophyta) were prepared using different solvents of increasing polarity, including dichloromethane, methanol, ethanol, and water. Of the extracts screened, the dichloromethane extracts of H. musciformis and P. gymnospora exhibited the highest activities and were subjected to bioassay-guided fractionation in hexane and chloroform. The chloroform fractions of the P. gymnospora and H. musciformis extracts showed molluscicidal activity at values below 40 μg·mL−1 (11.1460 μg·mL−1 and 25.8689 μg·mL−1, resp.), and the chloroform and hexane fractions of P. gymnospora showed larvicidal activity at values below 40 μg·mL−1 (29.018 μg·mL−1 and 17.230 μg·mL−1, resp.). The crude extracts were not toxic to A. salina, whereas the chloroform and hexane fractions of P. gymnospora (788.277 μg·mL−1 and 706.990 μg·mL−1) showed moderate toxicity, indicating that the toxic compounds present in these algae are nonpolar

Evaluating the impact of modeling the family effect for clonal selection in potato-breeding programs

Because of its wide distribution, high yield potential, and short cycle, the potato has become essential for global food security. However, the complexity of tetrasomic inheritance, the high level of heterozygosity of the parents, the low multiplication rate of tubers, and the genotype-by-environment interactions impose severe challenges on tetraploid potato–breeding programs. The initial stages of selection take place in experiments with low selection accuracy for many of the quantitative traits of interest, for example, tuber yield. The goal of this study was to investigate the contribution of incorporating a family effect in the estimation of the total genotypic effect and selection of clones in the initial stage of a potato-breeding program. The evaluation included single trials (STs) and multi-environment trials (METs). A total of 1,280 clones from 67 full-sib families from the potato-breeding program at Universidade Federal de Lavras were evaluated for the traits total tuber yield and specific gravity. These clones were distributed in six evaluated trials that varied according to the heat stress level: without heat stress, moderate heat stress, and high heat stress. To verify the importance of the family effect, models with and without the family effect were compared for the analysis of ST and MET data for both traits. The models that included the family effect were better adjusted in the ST and MET data analyses for both traits, except when the family effect was not significant. Furthermore, the inclusion of the family effect increased the selective efficiency of clones in both ST and MET analyses via an increase in the accuracy of the total genotypic value. These same models also allowed the prediction of clone effects more realistically, as the variance components associated with family and clone effects within a family were not confounded. Thus, clonal selection based on the total genotypic value, combining the effects of family and clones within a family, proved to be a good alternative for potato-breeding programs that can accommodate the logistic and data tracking required in the breeding program