Divergência e variabilidade genética de genótipos superiores de seringueira

The objective of this work was to estimate the genetic variability and divergence among 22 superior rubber tree (Hevea sp.) genotypes of the IAC 400 series. Univariate and multivariate analyses were performed using eight quantitative traits (descriptors), including yield. In the univariate analyses, the estimated parameters were: genetic and environmental variances; genetic and environmental coefficients of variation; and the variation index. The Mahalanobis generalized distance, the Tocher agglomerative method and canonical variables were used for the multivariate analyses. In the univariate analyses, variability was verified among the genotypes for all the variables evaluated. The Tocher method grouped the genotypes into 11 clusters of dissimilarity. The first four canonical variables explained 87.93% of the cumulative variation. The highest genetic variability was found in rubber yield-related traits, which contributed the most to the genetic divergence. The most divergent pairs of genotypes are suggested for crossbreeding. The genotypes evaluated are suitable for breeding and may be used to continue the IAC rubber tree breeding program.O objetivo deste trabalho foi estimar a divergência e a variabilidade genética entre 22 genótipos superiores de seringueira (Hevea sp.) da série IAC 400. Análises univariadas e multivariadas foram realizadas com oito caracteres quantitativos (descritores), incluindo produtividade. Na análise univariada, os parâmetros estimados foram: variâncias genética e ambiental, coeficientes de variação genética e ambiental, e índice de variação. A distância generalizada de Mahalanobis, o método aglomerativo de Tocher e variáveis canônicas foram utilizados nas análises multivariadas. Nas análises univariadas, verificou-se variabilidade entre os genótipos para todas as variáveis avaliadas. O método de Tocher agrupou os genótipos em 11 grupos de dissimilaridade. As quatro primeiras variáveis canônicas explicaram 87,93% da variação acumulada. A maior variabilidade genética foi encontrada em variáveis relacionadas à produtividade de borracha, que foram as que mais contribuíram para a divergência genética. Os pares de genótipos identificados como mais divergentes são indicados para cruzamentos. Os genótipos avaliados são adequados para o melhoramento genético e podem ser utilizados para continuar o programa de melhoramento da seringueira do IAC

Common bean genotypes for agronomic and market-related traits in VCU trials

Value for Cultivation and Use (VCU) trials are undertaken when evaluating improved common bean (Phaseolus vulgaris L.) lines, and knowledge of agronomic and market-related traits and disease reaction is instrumental in making cultivar recommendations. This study evaluates the yield, cooking time, grain color and reaction to anthracnose (Colletotrichum lindemuthianum), Fusarium wilt (Fusarium oxysporum f. sp. phaseoli) and Curtobacterium wilt (Curtobacterium flaccumfaciens pv. flaccumfaciens) of 25 common bean genotypes derived from the main common bean breeding programs in Brazil. Seventeen VCU trials were carried out in the rainy season, dry season and winter season from 2009 to 2011 in the state of São Paulo. Analyses of grain color and cooking time were initiated 60 days after harvest, and disease reaction analyses were performed in the laboratory under controlled conditions. In terms of yield, no genotype superior to the controls was observed for any of the seasons under consideration. Grains from the dry season exhibited better color, while the rainy season led to the shortest cooking times. The following genotypes BRS Esteio, BRS Esplendor and IAC Imperador were resistant to anthracnose, Fusarium wilt and Curtobacterium wilt and, in general, genotypes with lighter-colored grains were more susceptible to anthracnose and Fusarium wilt

Diversidade genética em acessos de feijoeiro avaliada por meio de dados morfo-agronômicos e de RAPD

Bancos de germoplasma guardam amostras de genótipos, variedades melhoradas, crioulas e espécies selvagens, todas genericamente denominadas acessos. A importância da caracterização de bancos de germoplasma reside na identificação e no conhecimento de características relevantes para o melhoramento genético e para conservação ex situ do germoplasma. Avaliou-se a diversidade genética entre 220 acessos de feijoeiro de um banco brasileiro de germoplasma de feijoeiro localizado no IAC (Instituto Agronômico, Campinas), por meio de 23 descritores morfo-agronômicos e 19 locos de RAPD. Os acessos correspondem a genótipos do pool gênico andino e mesoamericano e também por cultivares resultantes de programas de melhoramento de feijoeiro. Os acessos mesoamericanos e as cultivares melhoradas foram agrupados em um mesmo grupo, distintamente dos acessos andinos. Com base nos dados moleculares, 47% de similaridade genética foi detectada entre acessos mesoamericanos e resultados semelhantes foram observados para as cultivares melhoradas (50%). Os andinos apresentaram 60% de similaridade genética. O cluster formado pelas cultivares melhoradas e genótipos mesoamericanos apresentou diferenças quanto à coloração do tegumento. Ambos os conjuntos de dados, moleculares e morfo-agronômicos, foram igualmente eficientes para quantificação e estruturação da diversidade genética de acessos de feijoeiro. Essas informações poderão ser utilizadas para orientação de cruzamentos e para a conservação adequada do banco de germoplasma de feijoeiro do IAC.Germplasm banks store genotype samples, improved varieties, landraces and wild species, all generically denominated accessions. The importance of characterizing germplasm banks is based on the identification and knowledge of relevant traits for genetic improvement and ex situ germplasm conservation. Thus, the present study had as aim the evaluation of the genetic diversity among 220 accessions of a Brazilian common bean germplasm bank of the "Instituto Agronômico de Campinas" (IAC) by means of 23 morpho-agronomical descriptors and 19 RAPD loci. These accessions correspond to genotypes from the Andean and Middle American gene pool as well as from cultivars derived from common bean improvement programs. The Middle American accessions and the improved cultivars were clustered into one group, distinct from the one formed by the Andean accessions. In relation to the molecular data, 47% of the genetic similarity was detected among the Middle American accessions, and similar results were observed for the improved cultivars (50%). The Andean accessions revealed 60% of genetic similarity. The cluster constituted by the improved cultivars and the Middle American genotypes differed, basically, in tegument color. Both molecular and morpho-agronomical data sets were equally effective to quantify and organize the genetic diversity of common bean accessions. This information may be useful to direct crosses and for the proper organization of the IAC germplasm bank

Antixenosis of bean genotypes to Chrysodeixis includens (Lepidoptera: Noctuidae)

O objetivo deste trabalho foi avaliar genótipos de feijoeiro quanto à resistência a lagarta-falsa-medideira (Chrysodeixis includens). Inicialmente, foram realizados testes com chance de escolha com 59 genótipos, divididos em três grupos, de acordo com a intensidade de coloração das folhas (verde‑escura, verde‑clara e verde‑médio), para avaliar a preferência quanto à oviposição. Em seguida, selecionaram-se 12 genótipos com grande potencial de resistência, assim como dois padrões comerciais suscetíveis. Com estes genótipos, realizaram-se novos ensaios de oviposição, em casa de vegetação, além de testes de atratividade e consumo, em condições de laboratório (26±2ºC, 65±10% UR e fotófase de 14 h luz: 10 h escuro). No teste sem chance de escolha, com adultos, em casa de vegetação, os genótipos 'IAC Jabola', Arcelina 1, 'IAC Boreal', 'Flor de Mayo' e 'IAC Formoso' foram os menos ovipositados, tendo apresentado resistência do tipo antixenose à oviposição. No teste com chance de escolha, com larvas, Arcelina 4, 'BRS Horizonte', 'Pérola', H96A102‑1‑1‑1‑52, 'IAC Boreal', 'IAC Harmonia' e 'IAC Formoso' foram os genótipos menos consumidos, o que indica antixenose à alimentação. No teste sem chance de escolha, todos os genótipos (exceto 'IAPAR 57') expressaram níveis moderados de antixenose à alimentação de larvas de C. includens.The objective of this work was to evaluate bean genotypes for resistance to soybean looper (Chrysodeixis includens). Initially, free‑choice tests were carried out with 59 genotypes, divided into three groups according to leaf color intensity (dark green, light green, and medium green), in order to evaluate oviposition preference. Subsequently, 12 genotypes with high potential for resistance were selected, as well as two susceptible commercial standards. With these genotypes, new tests were performed for oviposition in a greenhouse, besides tests for attractiveness and consumption under laboratory conditions (26±2ºC, 65±10% RH, and 14 h light: 10 h dark photophase). In the no‑choice test with adults, in the greenhouse, the 'IAC Jabola', Arcelina 1, 'IAC Boreal', 'Flor de Mayo', and 'IAC Formoso' genotypes were the least oviposited, showing antixenosis‑type resistance for oviposition. In the free‑choice test with larvae, Arcelina 4, 'BRS Horizonte', 'Pérola', H96A102‑1‑1‑1‑52, 'IAC Boreal', 'IAC Harmonia', and 'IAC Formoso' were the less consumed genotypes, which indicates antixenosis to feeding. In the no‑choice test, all genotypes (except for 'IAPAR 57') expressed moderate levels of antixenosis to feeding against C. includens larvae

Efficiency in the use of phosphorus by common bean genotypes

Common bean (Phaseolus vulgaris L.) is frequently grown in weathered soils with low phosphorus (P) availability, and this is one of the main limitations on its production. This study aimed to assess 20 common bean genotypes in a hydroponic system to select the best P concentration for inducing nutritional deficiency and to classify the genotypes in terms of nutrient utilization efficiency. The concentrations of P applied were 8.00, 4.00, 2.00 and 0.05 mg L¹. At 21 days, in the plot subjected to an application of the most severe stress, the 0.05 mg L¹ dose of P, had smaller plant size and early leaf abscission was observed. The 4.00 mg L¹ dose of P was the most efficient in inducing stress for discrimination of cultivars in terms of efficiency of use of P. The following genotypes: IAPAR 81, Carioca Comum, IAC Carioca Tybatã, IAC Imperador and G 2333 stood out as being efficient and responsive to P, while the two cultivars DOR 364 and Jalo Precoce were the most inefficient and unresponsive

Influence of high temperature on the reproductive biology of dry edible bean (Phaseolus vulgaris L.)

The aim of this study was to investigate the effect of heat stress on 12 bean genotypes through the analysis of their reproductive biology in terms of flowering, pollen viability, meiotic behavior, and production. Plants were grown in a climate chamber at 25-20 °C (day and night) and at a high temperature treatment 37-26 °C (day and night) from the vegetative (V4) development stage to physiological maturity. The experimental design was 2 × 12 factorial arrangement with six replications and the factors consisted of heat treatments and genotypes. In three replications, the number of newly opened flowers was checked daily. At physiological maturity, the following traits were evaluated: percentage of pod set, number of pods, number of viable seeds, number of aborted seeds, 100 seed weight, and seed yield (g per plant). The other three replications were used to collect flowers to create slides to study viability of the pollen grain and analyze the meiotic behavior. The heat treatment factor significantly affected the following traits: total number of pollen grains, number of flowers, number of pods, pod set, number of viable seeds, 100 seed weight, and seed yield. The raised temperature reduced these variables, except for percentage of pod set, and increased meiotic irregularities. The mean values regarding seed yield were 16.39 g per plant for the control treatment and 7.46 g per plant under high temperature. IAC Imperador, FT Nobre, Pérola, BRS Estilo, and IAC Diplomata stood out for higher bean seed yield under increased temperature

Desempenho da erva-cidreira (Lippia alba) para características relacionadas à produção de óleos essenciais

A Lippia alba (Verbenaceae) é um arbusto produtor de óleo essencial com importantes atividades biológicas, farmacológicas e aromatizantes. Visando o cultivo sustentado de uma nova espécie com potencial econômico, os objetivos deste trabalho foram avaliar o desempenho da L. alba para massa de folha fresca (MF), massa de folha seca (MS), sintomas de vírus (SV - Cucumber mosaic virus, CMV), rendimento de óleo essencial (RE) e composição química do óleo (CQ), e avaliar a estabilidade e adaptabilidade fenotípica para o caráter MS. Dez genótipos pertencentes a quatro grupos químicos foram testados em seis experimentos instalados no estado de São Paulo, Brasil, com delineamento em blocos ao acaso e duas plantas por parcela. Em Monte Alegre do Sul e Pindorama, foi utilizado espaçamento de 2,0 x 0,4 x 1,6 m e em Campinas, foram instalados quatro experimentos 1,0 x 0,4 x 0,6 m sob condições distintas de adubação e irrigação. O efeito de genótipo foi significativo para todas as características avaliadas, revelando elevada produtividade de folhas do IAC-16 (citral), RE Yamamoto et al. superior dos quimiotipos linalol e limoneno/carvona e susceptibilidade deste último ao CMV. As oscilações no desempenho dos genótipos nos diferentes experimentos foram de baixa magnitude para os caracteres fitoquímicos (RE e CQ) e nenhuma variação qualitativa foi observada para CQ. Os genótipos IAC-2 (linalol) e IAC-13 (limoneno/carvona) apresentaram-se estáveis para MS e com ampla adaptabilidade, e são recomendados para o início do cultivo da espécie. A presente pesquisa fornece subsídios também para o início de programas de melhoramento genético em L. alba.Lippia alba (Verbenaceae) is a shrub whose essential oil has important biological, pharmacological, and aromatizing properties. To reach the sustained cultivation of new species with economic potential, the present study aimed to evaluate L. alba performance for fresh leaf matter (FM), leaf dry matter (DM), virus symptoms (VS - Cucumber mosaic virus, CMV), oil yield (OY), and oil chemical composition (OC), and to evaluate DM stability and adaptability. Ten genotypes of four chemical groups (chemotypes) were evaluated in six experiments designed as randomized blocks with two plants per plot, over the whole State of São Paulo, Brazil. A 2.0 x 0.4 x 1.6 m spacing was used in Monte Alegre do Sul and Pindorama, while a 1.0 x 0.4 x 0.6 m spacing was used in Campinas, where four experiments were established under different irrigation and fertilization conditions. The genotype effect was significant (p < 0.05) for all traits evaluated, with high leaf productivity of IAC-16 (citral chemotype), best OY means in the linalool and limonene/carvone chemotypes, and susceptibility of the latter chemotype to CMV. The genotype performance oscillations in the six environments were significant for FM and DM, and despite their significance for phytochemical traits (OY and OC), they were of low magnitude. No qualitative variation was detected for OC. The IAC-2 (linalool) and IAC-13 (limonene/carvone) genotypes showed high stability and wide adaptability, and are recommended to establish initial cultivations of this species. This research also indicated genetic sources to start Lippia alba genetic breeding programs