RESUMO O feijão-caupi [Vigna unguiculata (L.) Walp.] é uma importante cultura socioeconomicamente, principalmente na região nordeste e, mais recentemente no centro-oeste do Brasil. Podridão cinzenta do caule causada pelo fungo Macrophomina phaseolina (Tassi) Goid, é importante em regiões semiáridas, onde as condições edafoclimáticas são favoráveis para o desenvolvimento da doença. O objetivo deste estudo foi avaliar a reação de 100 linhagens de feijão-caupi à dois isolados de M. phaseolina. Os experimentos foram conduzidos em delineamento inteiramente casualizado com cinco repetições (duas plantas por parcela). As principais variáveis analisadas foram comprimento da lesão e crescimento relativo a testemunha. Entre os acessos avaliados, 15% das linhagens foram resistentes ao isolado 59 e 11% foram resistentes ao isolado CMM 2106 de M. phaseolina. Portanto, os acessos podem ser utilizados como fontes de resistência a M. phaseolina pelos agricultores diretamente como cultivares ou em futuros cruzamentos de programas de melhoramento genético do feijão-caupi.

ABSTRACT Cowpea [Vigna unguiculata (L.) Walp.] is an important socioeconomic crop in Brazil, mainly in the Northeast and more recently in the Midwest of Brazil. Charcoal rot caused by Macrophomina phaseolina (Tassi) Goid, is an important disease in semiarid regions, where edaphoclimatic conditions are favorable to the development of disease. The aim of this study was to evaluate the response of 100 cowpea lines to two isolates of M. phaseolina. The experiments were conducted in a completely randomized design, with five replications (two plants per pot). The main variables evaluated were lesion length and relative growth compared to control (RGCC). Among the evaluated accessions, 15% of the lines were resistant to isolate 59 and 11% of the lines were resistant to isolate CMM 2106 of M. phaseolina. Therefore, these accessions can be used as a source of resistance to M. phaseolina by farmers directly as new cultivars or in future hybridizations of cowpea genetic breeding programs.

Resumo Cycnoches haagii é uma orquídea epífita alvo de muitos coletores, mas nenhuma referência foi encontrada na literatura sobre sua biologia reprodutiva. Assim, o objetivo deste estudo foi obter informações preliminares sobre os tipos de polinização e sua influência na viabilidade das sementes desta orquídea nativa do Cerrado brasileiro, a fim de viabilizar futuros programas de multiplicação e preservação. Foram realizadas polinizações entre flores da mesma planta (geitonogamia) ou plantas diferentes (xenogamia). As sementes obtidas das cápsulas foram semeadas em meio B&G, com concentração total e parcial de sais. Sementes de geitonogamia resultaram em 25% dos protocormos albinos e consequentemente em plântulas albinas. Este fenômeno não ocorreu em sementes oriundas de polinização xenogâmica. A análise de pigmentos mostrou que mesmo as plântulas albinas apresentaram clorofilas e carotenoides, porém em concentrações significativamente menores, 16% e 37% respectivamente, em relação às plântulas pigmentadas. A polinização geitonogâmica deve ser evitada em programas de propagação da orquídea C. haagii devido à origem de plântulas albinas. Além disso, a polinização xenogâmica mostrou-se um método muito interessante para a obtenção de mudas com fenótipo albino, material vegetal muito intrigante para futuras investigações.

Abstract Cycnoches haagii Barb. Rodr. is an epiphytic orchid very targeted by collectors, but no reference was found in the literature about its reproductive biology. Thus, the purpose of this study was to obtain initial information regarding pollination types and its influence on seed viability of this native orchid of the Brazilian Cerrado, in order to enable future propagation and preservation programs. Pollination among flowers of the same plant (geitonogamy) or different plants (xenogamy) were carried out. Seeds extracted from the capsules were sown in B&G medium, with full and half strength. Seeds from geitonogamic resulted in 25% of albino protocorms and consequently in albino seedlings. This phenomenon did not occur in seedlings derived from xenogamic pollination. Pigment analysis showed that even the albino seedlings presented chlorophylls and carotenoids, however, in significantly minor concentrations, 16% and 37% respectively, in relation to green seedlings. Geitonogamic and xenogamic pollinations resulted in C. haagii viable seeds with high germination percentage (90%) under in vitro conditions. The germination of seeds from xenogamic pollination resulted in chlorophyll or normal seedlings only, and can be recommended at conservation programs. On the other hand, although geitonogamic pollination should be avoided at conservation programs of this orchid species as it leads to albino seedlings, it showed a very interesting system to obtain seedlings with this phenotype, an interesting plant material to future investigation.

RESUMO: O fungo Macrophomina phaseolina é o agente etiológico da podridão cinzenta do caule, uma das mais importantes doenças na cultura do feijão caupi em regiões semiáridas, podendo ocasionar perdas de 100%. A busca por genótipos resistentes exige uma fenotipagem eficiente. Além disso tem o problema da grande variação na agressividade entre isolados. Este trabalho teve como objetivos 1) testar três metodologias de inoculação em condições semiáridas, e 2) avaliar a agressividade de isolados de M. phaseolina. No primeiro experimento, conduzido em ambiente protegido, avaliou-se metodologias de inoculação em duas linhagens de caupi, por três métodos de inoculação e três isolados do patógeno. No segundo experimento, 15 isolados de M. phaseolina foram inoculados em uma cultivar de caupi para avaliar a agressividade do patógeno. Pela avaliação do comprimento das lesões e da severidade da doença por meio de um índice, identificamos o método de inoculação por palito de dente mais eficiente pois permitiu discriminar os genótipos estudados e a agressividade do patógeno.

ABSTRACT: The fungi Macrophomina phaseolina is the charcoal rot causal agent, one of the most important cowpea crop disease in semiarid regions can causes 100% yield losses. The search for resistant genotypes requires efficient phenotyping. In addition, there is the problem of great variation in aggressiveness between isolates. This study aimed to 1) test three methods of inoculation in semiarid conditions, and 2) to evaluate the aggressiveness of isolates of M. phaseolina. In the first experiment carried out in greenhouse, the inoculations methods were evaluated, using two cowpea lines, three inoculation methods and three pathogen isolates. On the second experiment, fifteen M. phaseolina isolates were inoculated in one cultivar to evaluate their aggressiveness. By assessing the length of the lesions and the severity of the disease using an index, we identified the toothpick inoculation method as the most efficient. Toothpick method allowed to discriminate the genotypes and the aggressiveness of the pathogen.

RESUMO No Brasil, as aceroleiras, quando infectadas por Meloidogyne enterolobii, apresentam redução na produtividade e na qualidade dos frutos. Uma das alternativas para solucionar este problema é a utilização de porta-enxerto resistente a esse patógeno. O objetivo deste trabalho foi avaliar a reação de 22 acessos de aceroleira a M. enterolobii, visando identificar, pelo menos, um porta-enxerto resistente. O experimento foi conduzido em blocos ao acaso, com 10 repetições, sendo cada parcela formada por 10 plantas. Cada planta foi inoculada com 350 ovos mais juvenis de segundo estádio de M. enterolobii e, após 90 dias, foram determinados o índice de galhas (IG) e o fator de reprodução (FR). As variáveis foram analisadas pela metodologia de modelos mistos (REML/BLUP). Com base nas duas variáveis avaliadas, destacaram-se os acessos, ACO-13, ACO-14, ACO-18 e BRS Apodi com quatro a seis plantas com reação de resistência ao nematoide-das-galhas, mas a avaliação dos acessos deve ser feita sob maiores doses de inóculo e por tempo mais longo.

ABSTRACT In Brazil, acerola trees infested by Meloidogyne enterolobii present lower yield and fruit quality. The use of rootstocks resistant to this pathogen is one of the alternatives to overcome this problem. This study aimed to assess the reaction of 22 acerola accessions to M. enterolobii, aiming to identify at least one resistant rootstock. The experiment was carried out in a randomized block design with 10 replications and each plot consisting of 10 plants. Each plant was inoculated with 350 eggs and second-stage juveniles of M. enterolobii, with the gall index (GI) and reproduction factor (RF) being determined after 90 days. The variables were analyzed using the mixed model methodology (REML/BLUP). The accessions ACO-13, ACO-14, ACO-18, and BRS Apodi stood out with four to six plants showing resistance reaction to the root-knot nematode, but the assessment of accessions should be performed under a higher density inoculum and longer time.

Abstract The objectives of this study were to estimate genetic parameters and identify traits that contribute to early yield in Manihot esculenta Crantz. Ten traits were evaluated in two experiments, one with 138 genotypes and the other with 133, using a completely randomized block design with four replications. All genotype effects were significant. The accuracy was high for the traits, except leaf retention (0.57), and reliability ranged from 0.33 to 0.75. Root weight (RW) and number of roots (NR) showed the highest selection effectiveness (CV r ), although the estimate was less than 1. Moreover, RW and NR obtained high genetic correlation (0.70). Path analysis showed that only number of roots had a significant direct effect on root weight (0.49), and no indirect effect was found. Therefore, accessions exhibited sufficient genetic variability, and indirect selection based on early evaluation of number of roots can be applied in cassava breeding for fresh root yield, increasing gain over time.

Information about genetic control of plant reaction to pathogens is essential in plant breeding programs focusing resistance. This study aimed to obtain information about genetic control of the angular leaf spot reaction in leaves and pods from common bean (Phaseolus vulgaris L.) line ESAL 686. This line was crossed with cultivars Jalo EEP 558 (resistant), Cornell 49-242 (resistant) and Carioca MG (susceptible). Generations F1, F2 and backcrosses (BC11 and BC21) were obtained. In the dry season (2009), parents and respective populations were evaluated for angular leaf spot reaction under field conditions. Disease severity was evaluated on leaves and pods using diagrammatic scales. Severity scores were obtained and mean and variance genetic components were estimated for both. Segregation of F2 generation was analyzed for some crosses. Different genes control angular leaf spot reaction in leaves and pods. Mean and variance components showed predominance of additive effects. Heritability was high, however, was greater on pods than on leaves which indicated that leaf reaction is more influenced by the environment.