ABSTRACT. Black spot (Asperisporium caricae) is one of the main foliar fungal diseases of papaya crops. This disease acts directly on leaves and fruits causing leaf area reduction and fruit deterioration. The quantification of diseases is a fundamental part of the disease management and control process; therefore, a scale is required to help quantify black spot disease. The objective of this work was to propose a standardized methodology to quantify black spot severity in papaya leaves. A scale was developed considering the maximum and minimum values of the disease in the field that included eight levels of severity: 0.1, 0.3, 0.6, 1.0, 2.3, 5.0, 10.0, and 20.0%. Without the aid of a scale the disease is often overestimated, with absolute errors of approximately 75%. When the scale was used, 100% of the evaluators showed improved accuracy and precision, and absolute error was reduced to the 10% range. The scale also provided good repeatability and high reproducibility. The use of the scale provided an improvement in the R2 values, with mean values of 93 and 92 in the second and third evaluations, respectively, demonstrating that the scale is useful for different aspects of the pathosystem of A. caricae, such as for determining the efficiency of fungicides, characterization of varietal resistance, construction of the disease progression curve, and estimation of damage.

Resumo: O objetivo deste trabalho foi avaliar as influências dos fatores genótipos de milho (Zea mays), safras agrícolas, texturas dos endospermas, fundo genético e bases genéticas nas taxas de haploides putativos (THPs), conforme a expressão do gene R1-navajo (R1-nj). Foram avaliados 41 genótipos de milho como receptores de pólen, em cruzamentos com o indutor “Krasnodar haploid inducer”, em duas safras (verão e inverno), no município de Maringá, no estado do Paraná, Brasil. O delineamento experimental foi o inteiramente casualizado com dez repetições (espigas). A variável resposta analisada foi a THP determinada pela proporção de haploides putativos, obtidos com base no marcador R1-nj, em relação ao número de sementes diploides por espiga. Posteriormente, foram utilizados modelos lineares generalizados para escolher o mais adequado para explicar a THP em função dos fatores testados. As safras, os genótipos e a interação safras x genótipos afetaram significativamente a THP, o que evidencia a dependência destes fatores na expressão do marcador fenotípico baseado na pigmentação por antocianina e determinado pelo gene dominante R1-nj. O número de agrupamentos formados pelos genótipos foram diferentes em cada safra. Dez genótipos apresentaram taxas maiores no verão do que no inverno. As texturas dos endospermas, as bases genéticas e o fundo genético não interferiram na THP.

Abstract: The objective of this work was to evaluate the influences of the factors corn (Zea mays) genotypes, crop seasons, endosperm texture, genetic background, and genetic basis on putative haploid rates (PHRs) according to the expression of gene R1-navajo (R1-nj). Forty-one corn genotypes were evaluated as pollen receptors, in crosses with the Krasnodar haploid inducer, in two crops (summer and winter), in the municipality of Maringá, in the state of Paraná, Brazil. The experimental design was completely randomized with ten replicates (ears). The response variable analyzed was the PHR, determined by the proportion of putative haploids, obtained through the R1-nj marker, in relation to the number of diploid seeds in each ear. Subsequently, generalized linear models were used to choose the one best fit to explain the PHR in function of the tested factors. Crop seasons, genotypes, and the crop seasons x genotypes interaction affected significantly the PHR, showing the dependence of these factors on the expression of the phenotypic marker based on anthocyanin pigmentation and determined by gene R1-nj. The number of clusters formed by the genotypes was different in each crop season. Ten genotypes showed higher rates in summer than in winter. Endosperm texture, genetic basis, and genetic background did not affect the PHR.

RESUMO A aplicação de fungicidas é a principal medida de controle da pinta-preta do mamoeiro. O controle biológico é uma alternativa, sendo a seleção de fungos micoparasitas a primeira etapa em programas com essa finalidade. Objetivou-se obter e selecionar fungos com potencial para o biocontrole da pinta-preta do mamoeiro. Coletaram-se, em diferentes regiões e patossistemas, 24 isolados, os quais foram identificados morfologicamente e pelo sequenciamento da região ITS. Para avaliar o potencial micoparasita, conduziram-se, em telado, dois ensaios, em blocos casualizados, com três repetições, sendo os isolados obtidos inoculados sobre folhas de mamoeiro com lesões de pinta-preta. Avaliaram-se o tempo médio para o aparecimento dos sinais de micoparasitismo e a incidência de lesões de pinta-preta micoparasitadas. Dos 24 isolados obtidos, dez eram de Hansfordia pulvinata, dois de Lecanicillium lecaniium, dois de Simplicillium lanossoniveum, um de Sarocladium implicatum e nove de Acremonium spp. Observou-se ampla variabilidade dos isolados em micoparasitar a pinta-preta, com destaque para os isolados H-611, H-613, H-614 e H-615, por apresentarem as maiores médias de colonização. Os resultados permitem afirmar que H. pulvinata apresenta grande potencial para ser utilizado como agente de biocontrole de Asperisporium caricae.

ABSTRACT The use of fungicides is the main control measure against the black-spot disease of papaya. The biological control is an alternative to that, being the selection of mycoparasitic fungi the first step in programs aiming at this kind of control. This study aimed to obtain and select fungi with potential to the biocontrol of the black spot disease of papaya. For this purpose, 24 isolates were collected from different regions and pathosystems, and then identified morphologically and by the ITS region sequencing. In order to evaluate the mycoparasite potential, two assessments, in a randomized block design, with three replications, were carried out in a shadehouse, being the obtained isolates inoculated on papaya leaves with black spot lesions. The average time for the appearance of mycoparasitism signs and the incidence of mycoparasitized black spot lesions were evaluated. Of the 24 isolates obtained, ten were from Hansfordia pulvinata, two from Lecanicillium lecaniium, two from Simplicillium lanossoniveum, one from Sarocladium implicatum and nine from Acremonium spp. A wide variability, concerning the mycoparasitism on black spot lesions, was observed, especially for the isolates H-611, H-613, H-614 and H-615, which showed the highest colonization averages. The results demonstrate that H. pulvinata has a great potential to be used as a biocontrol agent against Asperisporium caricae.

Abstract In support of breeding of papaya (Carica papaya), the disease incidence and severity of powdery mildew (Ovulariopsis caricicola) were evaluated in papaya genotypes. Two experiments in complete randomized blocks were carried out, one in the field and the other in a greenhouse. In field experiments, the lowest mean disease incidence was observed on the genotypes ‘Costa Rica’ and ‘Baixinho Super’, and the lowest mean disease severity on ‘Caliman M5’, ‘GTF’, ‘SH 11-08’, and ‘JS 11’. In the greenhouse experiment, the genotypes ‘Caliman M5’, ‘Golden’, ‘Kapoho Solo’, ‘Waimanalo’, ‘Mamão Bené’, ‘SH 12-07’, ‘JS 12’, and ‘GTF’ had the lowest mean incidence in at least one evaluation. On the other hand, for severity, the genotypes ‘Diva’, ‘Sunrise Solo 72/12’, ‘Kapoho Solo PA’, ‘Waimanalo’, ‘Maradol’, ‘Maradol GL’, ‘SH 15-04’, ‘FMV, ‘JS 12-4’, ‘SH 12-07’ and ‘Sekati FLM’ had the lowest means. These results indicate these genotypes for a possible use in breeding for reduction of powdery mildew intensity.

ABSTRACT Because of its multi-purpose nature, popcorn has sparked the interest of the World Trade Organization as regards fungal contamination by mycotoxins. However, no investigations have been conducted on popcorn for resistance of genotypes to ear rot. The aim of this study was to evaluate the potential of popcorn genotypes as to resistance to ear rot and rotten kernels, as an initial step for the implementation of a breeding program with the popcorn crop in Northern Rio de Janeiro State, Brazil. Thirty-seven accessions from different ecogeographic regions of Latin America were evaluated in 2 cultivation periods, in a randomized block design with 4 replications. We evaluated the incidence of rotten ears, incidence of rotten ears caused by Fusarium spp., severity of ears with Fusarium spp. rot, and incidence of rotten kernels. The results were subjected to analysis of variance, and means were compared by the Scott-Knott clustering test (p < 0.05). A significant effect was observed for all evaluated variables, characterizing them as efficient in the discrimination of genotypic variability for reaction to fungal injuries in popcorn. The gene pool of the tropical and temperate Germplasm Collection evaluated here has the potential to generate superior segregants and provide hybrid combinations with alleles of resistance to diseases affecting ears and stored kernels. Based on the different variables and times, the experiment was conducted, and genotypes L65, L80, and IAC 125 showed the highest levels of resistance.

A pinta-preta é a principal doença fúngica foliar do mamoeiro, sendo o controle químico necessário para se conseguir produção comercial econômica. Medidas de controle alternativas aos fungicidas são necessárias para a produção sustentável de frutos de mamão de melhor qualidade. Objetivou-se, neste trabalho, determinar as condições de temperatura adequadas ao crescimento micelial e à esporulação in vitro de fungos hiperparasitas do agente causal da pintapreta do mamoeiro, potenciais agentes de biocontrole. Foram avaliados 18 isolados fúngicos (oito de Hansfordia pulvinata e dez de Acremoniumspp.), cultivados em meio BDA, às temperaturas de 15 ºC, 20 ºC, 23 ºC, 25 ºC, 27 ºC e 30 ºC, sob fotoperíodo de 12 horas. Observou-se, para isolados de H. pulvinata, que temperaturas amenas (em torno de 21 ºC) propiciam máximas de crescimento micelial e esporulação. Para os isolados de Acremonium spp., o ponto ótimo para crescimento micelial e esporulação ocorre no intervalo de 20-25 ºC.

Black spot is the major papaya foliar fungal disease, being its chemical control necessary to achieve an economic commercial production. Alternative control methods, concerning fungicides, are necessary for the sustainable production of higher quality papaya fruits. Among them, biological control lacks basic studies. This study aimed to determine the proper temperature conditions for in vitro mycelial growth and sporulation of hyperparasites fungi isolated from Asperisporium caricae in papaya, which are potential biocontrol agents. A total of 18 fungal isolates (eight from Hansfordia pulvinata and ten from Acremonium spp.) were grown on PDA medium, at 15 ºC, 20 ºC, 23 ºC, 25 ºC, 27 ºC and 30 ºC, under a 12-hour photoperiod. For H. pulvinata isolates, mild temperatures around 21 ºC result in maximum mycelial growth and sporulation. For Acremonium spp. isolates, the optimum temperature for mycelial growth and sporulation occurs at 20-25 ºC.

Genótipos crioulos são importantes fontes de genes de adaptação, rusticidade e resistência de plantas a doenças bióticas e a estresse ambiental. Avaliou-se neste trabalho o potencial genético de contribuição de genótipos crioulos de mamoeiro na resistência a mancha-de-phoma. O experimento, implantado em blocos casualizados com seis repetições, foi composto de 24 progênies dioicas de meios-irmãos de mamoeiro que segregaram para o sexo, sendo avaliadas apenas as plantas com flores femininas. Foram estimados os componentes de variância e o valor genético de progênies para incidência e severidade de mancha-de-phoma via modelos mistos. As estimativas de herdabilidade e acurácia seletiva permitiram predizer situação muito favorável à seleção de progênies resistentes, com destaque para as progênies STA-02, STA-04, STA-05, STA-06, STA-07, STA-11, STA-12, STA-16, STA-21 e STA-22, com valores negativos de efeitos genéticos aditivos tanto para severidade quanto para incidência da doença nas folhas.

Landraces genotypes present with source of genes for adaptation, rusticity and resistance to disease and environmental stress. In this work the potential of landraces papaya genotypes in contributing to resistance genes phoma-spot was evaluated. The experiment was implemented in a randomized block design with six replications, was composed of 24 half-sib progenies of dioecious papaya - which segregated for sex. Only plants with female flowers were evaluated and estimate variance components and predict genetic value of landraces to incidence and severity of phoma-spot, by mixed model. Heritability estimates and selective accuracy demonstrate a favorable situation to the selection of progeny that can contribute to the reduction of disease. 'STA-02', 'STA-04', 'STA-05', 'STA-06', 'STA-07', 'STA-11', 'STA-12', 'STA-16', 'STA-21' and 'STA-22' showed negative values of additive genetic effects for both t incidence and severity of phoma-spot.

Variedades crioulas constituem alternativas para a ampliação da base genética e incorporação de genes de resistência a doenças em programas de melhoramento genético de plantas. Para tanto, há necessidade de utilização de métodos de seleção capazes de explorar eficientemente o material genético disponível. Com a finalidade de selecionar progênies de meios-irmãos derivadas de mamoeiros dióicos, para a efetiva concentração de alelos que condicionam resistência à pinta-preta, testaram-se os índices de seleção de Smith & Hazel, Pesek & Baker, Williams e Mulamba & Mock. A proposta de utilização de um índice visa buscar uma alternativa mais robusta na identificação de genótipos resistentes. Definiu-se a intensidade de seleção de 41,66%, correspondendo ao número de dez progênies. Os índices de Mulamba & Mock e Willians proporcionaram ganhos mais adequados para as características avaliadas quando utilizado o coeficiente de variação genético (CVg) como critério de peso econômico, sendo selecionadas as progênies 'STA-02', 'STA-04', 'STA-05', 'STA-08', 'STA-13', 'STA-15', 'STA-16', 'STA-17', 'STA-22' e 'STA-24', para compor um novo ciclo de seleção.

Landraces are alternatives for widening the genetic base and for incorporation of disease resistance genes in plant breeding programs. For this the use of screening methods capable of efficiently exploiting the available genetic material are needed. With the goal of selecting half-sib families of papaya for a favorable alleles concentration for resistance to black spot, the selection indices of Smith & Hazel, Pesek & Baker, Williams, and Mulamba & Mock were tested. The proposed use of an index aims to seek a more robust alternative to identify genotypes resistant The selection intensity of 41.66% was defined, corresponding to the number of ten progenies. The indices of Mulamba & Mock and Williams have provided gains more suitable for the evaluated characteristics when used the genetic variation coeficient (CVg) as criterion of economic weight. This two methodologies helped select the following progenies 'STA-02', 'STA-04', 'STA-05', 'STA-08', 'STA-13', 'STA-15', 'STA-16', 'STA-17', 'STA-22' and 'STA-24', to compose a new cycle of selection.

A resistência genética constitui alternativa sustentável para o controle do oídio. Objetivando indicar possíveis combinações híbridas que contribuam para a redução da severidade de oídio em folha de mamoeiro, foi realizado um cruzamento dialélico envolvendo oito genótipos, sendo quatro do grupo 'Solo' e quatro do grupo 'Formosa'. Os 56 híbridos (F1's e recíprocos) juntamente com seus genitores foram avaliados em blocos casualizados com quatro repetições. A severidade do oídio na folha foi quantificada em março e maio de 2010, respectivamente, aos 11 e 13 meses após o plantio. Com a média de cada tratamento foram estimadas as capacidades geral e específica de combinação. Assim, considerando as estimativas da capacidade combinatória obtidas com base na média das duas avaliações, as melhores combinações para os genitores avaliados quanto à severidade do oídio foram 'Maradol x Waimanalo', 'Maradol x Sunrise Solo 72/12', 'JS 12-4 x São Mateus', 'Sekati x Waimanalo', 'Sekati x Golden', 'Sekati x Sunrise Solo 72/12', 'Sekati x São Mateus', 'Waimanalo x São Mateus' e 'Golden x São Mateus'. Os resultados evidenciam ainda a possibilidade de obtenção de híbridos com potencial para redução da severidade do oídio provenientes de cruzamentos entre genótipos dos grupos 'Solo' e 'Formosa' e também em cruzamentos dentro do grupo 'Solo'.

Genetic resistance represents a sustainable alternative to control powdery-mildew in papaya crop. Diallelic crosses were performed among eight papaya genotypes, belonging to 'Solo' and 'Formosa' heterotic groups, four from each one with aiming to indicate possible hybrid combinations that contribute to reducing the severity of powdery-mildew on leaf. The 56 hybrid combinations (F1's and reciprocals) along with their parents were evaluated in a randomized complete block design with four replications. Powdery-mildew severity on leaves was measured in March and May 2010, respectively, at 11 and 13 months after planting. The general and specific combining ability were estimated from the severity data. Thus, considering the estimates of combining ability, the hybrids 'Maradol x Waimanalo', 'Maradol x Sunrise Solo 72/12', 'JS 12-4 x São Mateus', 'Sekati x Waimanalo', 'Sekati x Golden', 'Sekati x Sunrise Solo 72/12', 'Sekati x São Mateus', 'Waimanalo x São Mateus' e 'Golden x São Mateus' are the best combinations for the parents assessed to the severity of powdery-mildew. The results also show the possibility of obtaining hybrids with potential for reducing the severity of powdery-mildew, from crosses between genotypes of the groups 'Solo' and 'Formosa' and at crossings within the 'Solo' group.

A resistência genética constitui-se em alternativa sustentável para o controle de doenças em culturas agrícolas, sendo esta, no entanto, dependente da avaliação de populações naturais ou tradicionais visando à ampliação da base genética. Este trabalho relata a avaliação fenotípica de 24 progênies de mamoeiro, oriundas de genótipos crioulos, cultivados por pequenos agricultores no sul do Estado do Espírito Santo. Avaliaram-se características associadas à resistência à pinta-preta, importante doença desta cultura, causada pelo fungo Asperisporium caricae. Para fins comparativos, foram incluídas uma variedade resistente ('Maradol') e uma suscetível ('Golden') à pinta-preta. Pelos parâmetros genéticos estimados, concluiu-se que na população estudada há variabilidade genética quanto à resistência à pinta-preta suficiente para indicar a seleção recorrente como método de melhoramento.

Genetic resistance is a sustainable alternative to control diseases in crops, being indispensable the enlargement of the genetic base to introduce new resistance genes on developing cultivars. This study reports the phenotypic evaluation of 24 papaya progenies, originated of landraces cultivated for small farmers in south of the Espírito Santo State, Brazil. Characteristics related to the resistance to black-spot disease, induced by the fungi Asperisporium caricae were evaluated. For comparison one genotype resistant ('Maradol') and one susceptible ('Golden') to black-spot disease were included on the study. Based on the genetic parameters estimated, the studied population has genetic variability for resistance to black spot diseases appropriates for use of recurrent selection as crop breeding method.