Search

Bayesian methods and frequency-based approaches such GBLUP are used to estimate genomic genetic values in recurrent genomic selection. An important factor in genetic gain is prediction accuracy; therefore, the objective of the present study was to estimate the prediction accuracy of the following methods: GBLUP, Bayes A, Bayes B, Bayes Cπ, Bayes Lasso, and RKHS. After establishing the best method, different densities of SNP markers were tested. The experiment was implemented using an incomplete block design with three repetitions in two locations. Ninety-eight individuals were evaluated using 10,507 SNPs; the assessed traits were grain yield, popping expansion, and popcorn volume. The analyses were performed using R software and a ten-fold cross-validation system. The methods were compared using the t-test, via correlation networks and according to the time required to perform the analysis. The obtained results showed that the methods did not differ statistically with regard to selection accuracy, with high correlation estimates (

The aim of the present study was to investigate relations among ten traits in super-sweet corn genotypes assessed by means of simple correlation, path and canonical variable analyses, as well as to investigate the relative importance of such traits to the super-sweet corn breeding program developed at Darcy Ribeiro Northern Fluminense State University in order to develop strategies able to improve the efficiency in the selection of superior genotypes. Thus, trials comprising 3 × 6 partial diallel of super-sweet (sh2) corn were carried out, according to a short_textrandomized block design (RBD)short_text with four repetitions, in two different environments located in Northern Rio de Janeiro State, Brazil (Itaocara and Campos dos Goytacazes counties). The correlation study showed that traits such as ear diameter and useful short_textearshort_text length contributed the most to increase short_textearshort_text yield (without husk); the variable ear diameter stood out for having stronger direct effect on ear yield, as well as for presenting high heritability (0.95). The trait number of grains per ear row contributed the most to the variation between hybrids, whereas the trait useful ear length contributed the least. The canonical variables showed that the genetic backgrounds of sh2-gene donor populations had effect on recurrent populations, even after five backcrossing cycles, thus resulting in the formation of two divergent groups.

To date, no studies on the inheritance of Fusarium spp. ear rot resistance in popcorn are available. The purpose of this paper was to investigate the additive-dominance model to estimate the genetic components of variance, heritability and the inheritance pattern in a diallel for popcorn, by Hayman’s approach. The experiment was carried out in two environments, using eight parent lines. The following traits were measured: grain yield (GY), popping expansion (PE), incidence of ears infected by Fusarium (FusIE), total number of kernels infected by fungi (FunIK) and total number of kernels infected by Fusarium spp. (FusIK). The results indicated that the incidence of FusIK (Fusarium-infected kernels), FunIK (fungus-infected kernels), and FusIE (Fusarium-infected ears) is controlled by dominant genes. Parent L77 had a high number of favorable alleles for all resistance-related traits, as well as for PE. The strategy recommended for reduction of FunIK, FusIK, and FusIE consists of exploiting hetorosis using inbred lines with favorable alleles.

Among the ear rot pathogens, species of Fusarium cause significant economic losses to popcorn production. To generate popcorn genotypes resistant to Fusarium ear rot, the combining ability of popcorn lines in diallel crosses were assessed during two cropping years: the first from Mar to Sep 2015 and the second from Sep 2015 to Jan 2016. The traits analyzed were: average ear weight (AEW, kg ha−1); grain yield (GY, kg ha−1); popping expansion (PE, g mL−1), Fusarium incidence on ears (EIFU, %); Fusarium ear rot severity index (FSI, %), percentage of fungal-infected kernels (KIF), and percentage of Fusarium-infected kernels (KIFU). Non-additive genetic effects prevailed in the expression of resistance to Fusarium ear rot and grain yield, while additive effects were the most prominent in the expression of popping expansion. Among 56 hybrids, seven showed outstanding grain yield, desirable popping expansion, and resistance to Fusarium ear rot. The less susceptible hybrids to ear rot produced high grain yield and popping expansion. Two disease-related traits, KIFu and EIFu, allowed to best differentiate among the genotypes.

Polysora rust, caused by Puccinia polysora, is one of the most economically important foliar diseases of maize, and the use of resistant genotypes is the most efficient and economically appropriate measure to control this disease. In popcorn, damage caused by this disease is equivalent to that found in common maize. However, studies on the identification of sources of resistance in popcorn are much more scarce. This study aimed to evaluate the reaction of popcorn genotypes regarding polysora rust resistance. For this purpose, 37 temperate and tropical popcorn genotypes were evaluated in randomized block experiments with four replicates in two crop seasons, in Campos dos Goytacazes, RJ, Brazil. Disease intensity was estimated by quantifying incidence and severity using a diagrammatic scale, based on the plant and the leaf immediately below the first ear. We found that incidence can efficiently replace severity at low epidemic levels, facilitating field diagnostics. Also, we observed genetic variability for traits related to polysora rust resistance. The landraces PARA 172, ARZM 05083 and the line L80 are recommended to integrate breeding populations for Puccinia polysora resistance as they may carry favorable alleles for disease control.

The identification of the genes responsible for complex traits is highly promising to accelerate crop breeding, but such information is still limited for popcorn. Thus, in the present study, a mixed linear model-based association analysis (MLMA) was applied for six important popcorn traits: plant and ear height, 100-grain weight, popping expansion, grain yield and expanded popcorn volume per hectare. To this end, 196 plants of the open-pollinated popcorn population UENF-14 were sampled, selfed (S1), and then genotyped with a panel of 10,507 single nucleotide polymorphisms (SNPs) markers distributed throughout the genome. The six traits were studied under two environments [Campos dos Goytacazes-RJ (ENV1) and Itaocara-RJ (ENV2)] in an incomplete block design. Based on the phenotypic data of the S1 progenies and on the genetic characteristics of the parents, the MLMA was performed. Thereafter, genes annotated in the MaizeGDB platform were screened for potential linkage disequilibrium with the SNPs associated to the six evaluated traits. Overall, seven and eight genes were identified as associated with the traits in ENV1 and ENV2, respectively, and proteins encoded by these genes were evaluated for their function. The results obtained here contribute to increase knowledge on the genetic architecture of the six evaluated traits and might be used for marker-assisted selection in breeding programs.

The expansion of agriculture, coupled with the need for sustainable cropping, is one of the greatest challenges of the scientific community working on the generation of new cultivars adapted to abiotic stress conditions. The aim of this study was to evaluate the variability of popcorn lines as to responsiveness and efficiency in phosphorus use, as a first step towards the implementation of a breeding program interested in the practice of sustainable agriculture. Twenty-five popcorn lines were evaluated in two locations with different phosphorus levels in the soil, using a randomized block design. The following traits were measured: plant height, ear height, female flowering date, male flowering date, male-female flowering interval, ear diameter, ear length, 100-grain weight, grain yield, popping expansion, and expanded popcorn volume per hectare. A combined analysis of variance and test of means were performed, and the lines were classified as to their phosphorus use efficiency, according to their production performance in the different environments. The genetic diversity between the lines was estimated by Tocher’s and UPGMA clustering methods, using generalized Mahalanobis distance. Lines L59, P7, P2, P3, P4, P8, P10, P9, L66, L70, L69, and P5 were efficient and responsive, whereas lines L75, L80, L61, L77, L63, L65, P1, L54, L53, L88, and L71 were inefficient and nonresponsive. Genetic variability was greater in the environments with low phosphorus in the soil, suggesting that the selection pressure exerted in the stressing environment is a decisive factor to obtain a higher expression of variability.

É importante dimensionar adequadamente o tamanho de amostra, para estimação, com confiabilidade aceitável, do coeficiente de correlação linear de Pearson entre pares de caracteres. O objetivo deste experimento foi determinar o tamanho de amostra (número de plantas) para estimação do coeficiente de correlação linear de Pearson, entre 21 caracteres de crambe (Crambe abyssinica Hochst). Um experimento em campo foi conduzido no ano de 2008. Na colheita foram selecionadas, aleatoriamente, 75 plantas, nas quais foram mensurados 21 caracteres. Foram calculadas medidas de tendência central, de variabilidade, de assimetria e de curtose, verificada a normalidade e investigada a linearidade entre os caracteres. Foi calculado o tamanho de amostra, para estimação do coeficiente de correlação de Pearson, para as amplitudes do intervalo de confiança de 95%, iguais a: 0,15; 0,20; 0,25; 0,30; 0,35 e 0,40, para cada um dos 210 pares de caracteres. Para os 210 pares de caracteres de crambe estudados, o tamanho de amostra, para estimação do coeficiente de correlação linear de Pearson, para a amplitude do intervalo de confiança de 95% igual a 0,15, oscilou entre 8 e 665 plantas.