ABSTRACT This study aimed to verify if the genetic divergence between papaya lines, obtained by means of molecular markers, is correlated with heterosis in the hybrids for characteristics related to production, fruit quality and disease resistance. Eight parents and 56 hybrids obtained from diallel crosses were evaluated in randomized blocks, with four replicates. The number of commercial fruits (NCF), the average fruit weight (AFW), the productivity (PROD), the fruit firmness (FIRM) and the total soluble solids (TSS) were evaluated, as well as the severity of black spot on leaves (BSS) and fruits (BSSFr), phoma spot (PSS) and powdery mildew on leaves (PMS). Correlations were estimated between genetic divergence, obtained based on SSR, and heterosis, estimated for each characteristic in four possibilities of crossings within the diallel: i) all crossings; ii) between parents of the ‘Solo’ group; iii) between parents of the ‘Formosa’ group; and iv) between parents of ‘Solo’ with ‘Formosa’ group and ‘Formosa’ with ‘Solo’ group. Results indicate the possibility of exploring heterosis both in crossings between groups and in crossings within groups. The low magnitude of the estimates of correlation between heterosis and morphological characteristics of the hybrids with genetic distance obtained by SSR in the parents indicates that the behavior of hybrids cannot be inferred based on the genetic divergence between parents.
Abstract Recurrent selection is a method for developing new popcorn ( Zea mays L.) cultivars. We aimed to determine the selection accuracy and genetic gains for different selection strategies: estimates based exclusively on phenotypic data (PhEN), estimates based on phenotypic and genotypic data (PhEN + GEN), and estimates based exclusively on single nucleotide polymorphism (SNP) marker genotyping (GEN). For the GEN strategy, we tested, via simulation, the possibility of reducing the number of SNPs and increasing the training population. The traits evaluated were 100‐grain weight, ear height, grain yield, popping expansion, plant height, and popping volume. Field trials were undertaken with 98 S 1 progenies at two locations in an incomplete block design with three replications. The progenies’ parents were genotyped with a panel of ∼10,507 SNPs. As predicted by the GEN strategy at different selection intensities, the average annual genetic gain for the different traits were 29.1 and 25.2% higher than those of PhEN and GEN + PhEN for 98 candidates; 148.3 and 140.9% higher for 500; and 187.9 and 179.4% higher for 1,000 selection candidates, respectively. Recurrent genomic selection may result in high genetic gain, provided that: (a) phenotyping is accurate; (b) selection intensity is explored by genotyping several progenies and increasing the number of candidates; (c) genomic selection is used for early selection; and (d) the model is adjusted for a few more cycles of phenotyping. The simulation suggests that desirable values of genetic gain may be obtained by reducing the number of SNPs and increasing the training population size.
Snap bean is a popular and promising vegetable in Southeastern Brazil .The aim of the current study is to use the multivariate analysis as tool to select snap bean genotypes presenting desired agronomic traits.The study followed a randomized block experimental design, with 4 repetitions and 30 genotypes.The principal component and biplot analyses, as well as clustering, were conducted according to the UPGMA method in order to investigate the mean pod weight (MPW), number of seeds per pod (NSP), pod length (PL), pod width (PWi), total pods (MNP), weight of one hundred seeds (W100S), pod yield (PY) and grain yield (GY).The PL, NSP, MPW and W100S presented positive correlation with GY, besides their indication to direct genotype selection.The PWi and TP were efficient for PY selection.The multivariate analyses suggested the selection of lines UENF 7-10-1, UENF 7-12-1 and UENF 7-20-1, which presented good seed yield, as well as of UENF 14-22-3 and UENF 14-23-3, which showed aptitude to production.Lines located in Group II (UENF 14-4-3, UENF 15-6-4, UENF 7-4-1, UENF 7-9-1, UENF 7-7-1, UENF 7-5-1) did not have good performance in the measured traits and could be discarded.Line UENF 1445 "PARENT 19" proved its potential for seed yield, thus it was promising for the development of productive genotypes.Line 14-3-3 presented good aptitude for negatively correlated variables, because it associated good trait with morphology, seed yield, and pod and grain yield morphological traits.
Similar to many other human activities, the energy sector has a global concern with environmental issues. The use of renewable energy sources such as biomass is an alternative to the use of fossil fuels. Eight elephant grass genotypes showing energy production potential were herein assessed. The genotypes were grown from February 2014 to March 2016 in Campos dos Goytacazes County – Rio de Janeiro State, Brazil. They were fertilized with three different nitrogen doses (400, 1000 and 1600 kg N ha-1) and two potassium doses (200 and 500 kg K2O ha-1). The experiment followed a randomized block design, with three repetitions, using a split-plot factorial scheme. The aim of the current study was to assess the effect of different nitrogen and potassium doses in fertilizing different genotypes of elephant grass by analyzing the morphoagronomic traits. The lowest K dose (200 kg ha-1) was enough to generate the best outcomes in characteristics presenting significant effects. The N increase in the fertilization process did not promote dry matter production gains. The lowest N dose (400 kg ha-1) was enough to promote the highest values. As for the other traits assessed in the current study, although there was a genotype that showed statistically significant difference from any other genotype at a particular dose, the increasing N doses in the fertilization did not influence the performance of the genotypes. Key words: Renewable energy, biomass, mineral nutrients, Pennisetum purpureum Schum.
This work was carried out to study the physiological potential of artificially aged seed lots of maize. The specific aim of this study was to fit a simplified equation from Andreoli, , and present a methodology using probit regression analysis, given by the equation . We used seeds from three lots of the maize hybrid OC 705 which were submitted to the accelerated aging test, at the temperature of 43 ºC, every 24 hours. The simplified equation did not provide a good fit to the data, with r2 of at most 92%. Pearson's Chi-square test and the log-likelihood ratio Chi-square test indicated that probit regression had a good fit to the data, providing estimated values with high accuracy. It was observed that lot three maintained the highest vigor throughout the storage period.
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.
ABSTRACT Compared with the common corn, popcorn shows greater susceptibility to pests and diseases occurrence, being the use of resistant cultivars the most efficient strategy. In this regard, Germplasm Banks deserve special attention because they contain accessions that can be used as sources of resistance in breeding programs. The State University of Northern Rio de Janeiro (UENF) maintains a popcorn Germplasm Bank with accessions from tropical and temperate countries, including Diversity Centers for the species. In this study, we investigated the performance of 37 popcorn accessions landraces, hybrids, and inbreed lines ― from the Germplasm Collection of UENF’s Popcorn Breeding Program with respect to the fungal leaf diseases northern leaf blight (NLB) and southern leaf blight (SLB), caused by Exserohilum turcicum and Bipolaris maydis, aiming to select promising accessions for genetic resistance to be used in future crosses to generate new resistant cultivars for farmers. The dendrogram scattering by the UPGMA multivariate technique was efficient in discriminating resistant accessions. Satisfactory results were obtained for resistance to NLB in accessions L71, L75, L76, P7, and PARA-172, which can thus be considered remarkable sources of resistance. For resistance to SLB, the superior accessions that can be indicated as sources of resistance are ARZM-05083, ARZM-07049, and PARA-172.
RESUMO A mancha de Bipolaris, causada por Bipolaris maydis, é uma das principais doenças foliares de Zea mays, apresentando um considerável potencial de dano, notadamente, na cultura do milho-pipoca, embora trabalhos sobre este patossistema ainda sejam escassos. Neste trabalho, avaliaram-se as influências de diferentes meios de cultura sobre o crescimento micelial, esporulação e a infectividade de inóculo conidial de B. maydis em folhas da cultivar suscetível Beija-flor, de milho-pipoca. Para tal, instalaram-se experimentos em laboratório e em casa de vegetação em blocos casualizados com quatro repetições. Em laboratório, avaliaram-se o crescimento micelial e a esporulação de B. maydis em diferentes meios de culturas (Batata Dextrose Ágar, Feijão Ágar, Água de Coco Ágar, Arroz Polido Ágar, Folha de Milho Ágar e Lactose Caseína Ágar). Em casa de vegetação, avaliaram-se o número de lesões por folha e a incidência de doença na planta suscetível inoculada com uma suspensão de 104 conídios/mL. O meio de Arroz Polido Ágar foi o que mais promoveu o crescimento micelial do fungo, porém não favoreceu a esporulação. Para esporulação, destacaram-se os meios de cultura Batata Dextrose Ágar e Feijão Ágar. Maior número de folhas com sintoma da doença e maior número de lesões por folha foram obtidos com o inóculo produzido no meio Feijão Ágar. Palavras-Chave: Zea mays L., Crescimento micelial, Mancha de Bipolaris, Esporulação, Milho-pipoca.CULTURAL AND PATHOLOGICAL FEATURES OF Bipolaris maydis IN DIFFERENT CULTURE MEDIAABSTRACT. The Southern corn leaf blight, caused by Bipolaris maydis, is a major foliar disease of corn, presenting considerable potential of damage, especially in Zea mays, although studies with this pathosystem are still scarce. In this paper, the effect of different culture media was evaluated on mycelial sporulation and infectivity of conidial inoculum of B. maydis on leaves of the susceptible cultivar Beija-Flor, of corn-popcorn. Experiments in laboratory and greenhouse were installed in a randomized blocks design with four replications. The mycelial growth and sporulation of B. maydis on different culture media (Potato Dextrose Agar, Bean Agar, Coconut Water Agar, Rice Polished Agar, Corn Leaf Agar Lactose Casein Agar) were evaluated in the laboratory. In the greenhouse it was evaluated the number of lesions per leaf and the incidence of disease in susceptible plants inoculated with a suspension of 104 conidia/ml. The culture medium Polished Rice Agar promoted the highest mycelial growth, but did not promote sporulation. Sporulation was higher on culture media Potato dextrose Agar and Agar Bean. A greater number of leaves with symptoms of the disease and a higher number of lesions per leaf were obtained with the inoculum produced in the culture medium Bean Agar.Keywords: Zea mays L, Mycelial growth, Southern corn leaf bligh, Sporulation, Popcorn.
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