Escalas diagramáticas para avaliação do fenótipo de tubérculos de batata

Nos programas de melhoramento de batata existem diversos caráteres dos tubérculos que são avaliados com o auxílio de escalas diagramáticas. Entretanto, não há padronização das escalas entre os programas de melhoramento, fazendo com que cada programa adote a sua própria escala. O objetivo do trabalho foi elaborar e validar diferentes escalas diagramáticas para avaliação de caracteres relacionados ao fenótipo de tubérculos de batata. Foram considerados os caracteres: textura da periderme; formato; profundidade de olhos; coloração de polpa; coloração de palito após a fritura; coloração de “chips” após a fritura e coloração de pele. Dez avaliadores atribuíram notas aos tubérculos para os caracteres sem e com o uso das escalas. Foram avaliadas dez repetições classificadas em cada nota da respectiva escala utilizando o delineamento inteiramente casualizado. Os dados de todos avaliadores foram submetidos à análise de regressão linear entre as notas reais e as médias das notas dos avaliadores sem e com o uso da escala. Quando a avaliação foi realizada com o uso das escalas, todos os avaliadores melhoraram sua precisão, com aumento nos coeficientes de determinação para todos os caracteres estudados. Essas escalas apresentam-se como uma ferramenta bastante oportuna para auxiliar nas avaliações dos caracteres que compõe a aparência geral dos tubérculos, haja vista a falta de um sistema padrão de avaliação

Evaluating the impact of modeling the family effect for clonal selection in potato-breeding programs

Because of its wide distribution, high yield potential, and short cycle, the potato has become essential for global food security. However, the complexity of tetrasomic inheritance, the high level of heterozygosity of the parents, the low multiplication rate of tubers, and the genotype-by-environment interactions impose severe challenges on tetraploid potato–breeding programs. The initial stages of selection take place in experiments with low selection accuracy for many of the quantitative traits of interest, for example, tuber yield. The goal of this study was to investigate the contribution of incorporating a family effect in the estimation of the total genotypic effect and selection of clones in the initial stage of a potato-breeding program. The evaluation included single trials (STs) and multi-environment trials (METs). A total of 1,280 clones from 67 full-sib families from the potato-breeding program at Universidade Federal de Lavras were evaluated for the traits total tuber yield and specific gravity. These clones were distributed in six evaluated trials that varied according to the heat stress level: without heat stress, moderate heat stress, and high heat stress. To verify the importance of the family effect, models with and without the family effect were compared for the analysis of ST and MET data for both traits. The models that included the family effect were better adjusted in the ST and MET data analyses for both traits, except when the family effect was not significant. Furthermore, the inclusion of the family effect increased the selective efficiency of clones in both ST and MET analyses via an increase in the accuracy of the total genotypic value. These same models also allowed the prediction of clone effects more realistically, as the variance components associated with family and clone effects within a family were not confounded. Thus, clonal selection based on the total genotypic value, combining the effects of family and clones within a family, proved to be a good alternative for potato-breeding programs that can accommodate the logistic and data tracking required in the breeding program

Genomic prediction for complex traits across multiples harvests in alfalfa (Medicago sativa L.) is enhanced by enviromics

Abstract Breeding for dry matter yield and persistence in alfalfa (Medicago sativa L.) can take several years as these traits must be evaluated under multiple harvests. Therefore, genotype‐by‐harvest interaction should be incorporated into genomic prediction models to explore genotypes’ adaptability and stability. In this study, we investigated how enviromics could help to predict the genotypic performance under multiharvest alfalfa breeding trials by evaluating 177 families across 11 harvests under four cross‐validation scenarios. All scenarios were analyzed using six models in a Bayesian mixed model framework. Our results demonstrate that models accounting to the enviromics information led to an increase of genetic variance and a decrease in the error variance, indicating better biological explanation when the enviromic information was incorporated. Furthermore, models that accounted for enviromic data led to higher predictive ability (PA) in a reduced number of harvests used in the training data set. The best enviromic models (M2 and M3) outperformed the base model (GBLUP model—M0) for predicting adaptability and persistence across all cross‐validation scenarios. Incorporating environmental covariates also provided higher PA for persistence compared with the base model, as predictions increased from 0 to 0.16, 0.20, 0.56, and 0.46 for CV00, CV1, CV0, and CV2. The results also demonstrate that GBLUP without enviromics term has low power to predict persistence, thus the adoption of enviromics is a cheap and efficient alternative to increase accuracy and biological meaning

Nitrogen fertilization and genotype jointly drive bermudagrass (Cynodon spp.) productivity but are not associated with differences in SOC

Abstract Pastureland contributes a large share of the global soil C stock, much of which derives from root systems. Management practices like fertilization and the introduction of improved forages have clear benefits to aboveground forage production, but their impacts on belowground biomass (BGB) and hence soil C are less clear, especially in relatively understudied subtropical pastures. If fertilization and improved cultivars increase BGB, C sequestration may benefit. However, long‐term soil C stocks, and their associated ecosystem services, may be compromised if these practices sacrifice roots in favor of shoot production. We studied the aboveground and belowground biomass of nine bermudagrass (Cynodon spp.) genotypes in response to four escalating NPK fertilization rates and compared the soil C and N stocks among them. As expected, increasing fertilization improved forage accumulation (FA) although gains from additional N diminished at higher fertilization rates. A positive relationship between fertilization and BGB emerged but varied among genotypes. The latter identified potential tradeoffs between aboveground and belowground allocation in newly released and commercial forage varieties, which may affect pasture persistence and contributions to soil organic matter over time. Overall, we found subtle differences in soil organic C/soil organic N stocks among NPK fertilization rates and genotypes, with the strongest signal emerging from C isotopic analysis. Our results suggest that fertilization at the recommended rate and improved genotype selection minimized negative tradeoffs between aboveground and belowground biomass and did not elicit differences in SOC in the top 15 cm but likely contributed to ecosystem disservices as it relates to N losses

Ploidy Level and Genetic Parameters for Phenotypic Traits in Bermudagrass (Cynodon spp.) Germplasm

Bermudagrass (Cynodon spp.) is a forage and turf crop commonly used worldwide. The USDA bermudagrass germplasm set is composed of plant introductions (PI’s) collected around the world and contains different Cynodon species, primarily C. dactylon. The collection was screened in a replicated trial in Florida for forage yield, leaf width, nutritive value (NV), and Bermudagrass Stem Maggot (Atherigona reversura) (BSM), which is an invasive pest to the southeastern United States that damages bermudagrass fields. The goal of this research was to determine ploidy level and genome size in this USDA collection, and evaluate the influence of ploidy level in the estimation of genetic parameters for BSM, leaf width, dry matter yield, and NV traits. For chromosome counts using classical cytogenetics techniques, root tips and meristems were collected from a set of PI’s with known ploidy. The PI’s and cultivars with known chromosome counts were used as internal standards to run flow cytometry and estimate genome size of the PI’s with unknown ploidy. Ploidy level was determined for all accessions and were used to estimate genetic parameters of phenotypic traits. By providing information on ploidy levels and genetic parameters, this research will support breeding efforts and future selections for forage bermudagrass

Delayed colorectal cancer care during covid-19 pandemic (decor-19). Global perspective from an international survey

Background The widespread nature of coronavirus disease 2019 (COVID-19) has been unprecedented. We sought to analyze its global impact with a survey on colorectal cancer (CRC) care during the pandemic. Methods The impact of COVID-19 on preoperative assessment, elective surgery, and postoperative management of CRC patients was explored by a 35-item survey, which was distributed worldwide to members of surgical societies with an interest in CRC care. Respondents were divided into two comparator groups: 1) ‘delay’ group: CRC care affected by the pandemic; 2) ‘no delay’ group: unaltered CRC practice. Results A total of 1,051 respondents from 84 countries completed the survey. No substantial differences in demographics were found between the ‘delay’ (745, 70.9%) and ‘no delay’ (306, 29.1%) groups. Suspension of multidisciplinary team meetings, staff members quarantined or relocated to COVID-19 units, units fully dedicated to COVID-19 care, personal protective equipment not readily available were factors significantly associated to delays in endoscopy, radiology, surgery, histopathology and prolonged chemoradiation therapy-to-surgery intervals. In the ‘delay’ group, 48.9% of respondents reported a change in the initial surgical plan and 26.3% reported a shift from elective to urgent operations. Recovery of CRC care was associated with the status of the outbreak. Practicing in COVID-free units, no change in operative slots and staff members not relocated to COVID-19 units were statistically associated with unaltered CRC care in the ‘no delay’ group, while the geographical distribution was not. Conclusions Global changes in diagnostic and therapeutic CRC practices were evident. Changes were associated with differences in health-care delivery systems, hospital’s preparedness, resources availability, and local COVID-19 prevalence rather than geographical factors. Strategic planning is required to optimize CRC care