Caracteres agronômicos e fisiológicos associados ao progresso do melhoramento genético de trigo no Brasil

Knowledge the processes responsible for the progress of genetic gain in grain yield in wheat plant is an essential step for the development of high yield cultivars. The aims of the study were: a) Evaluate the duration of developmental phases in wheat cultivars and quantify the importance of each phase on grain yield and its components. b) characterize physiological and agronomically wheat cultivars released in different decades, to identify selection criteria for continued improvement of genetic progress in Brazil. c) Characterize Brazilian wheat cultivars developed in different decades for the nitrogen use efficiency (NUE). Ten wheat cultivars released from1940 to 2009, were examined for two years in a competition essay (2010 and 2011) and in 2011 an essay in green house was conducted with four nitrogen rates (0, 60, 120 e 180 kg N ha-1). We compared the duration of periods, agronomic and physiological traits (gas exchange) and nitrogen use efficiency (EUN) characters. The Breeding reduced time to anthesis and increased the grain filling, contributing to the increase in thousand kernel weight. The modern cultivars had the period terminal spikelet to anthesis increased (0,68 to 1,35 degree days year-1) over the years, contributing to the increase in the number of grains per spikelet, number of grains per spike, spike dry weight at anthesis and spike fertility index. The increase in grain yield was 29 kg ha-1 yr-1, with a genetic gain of 0,92% yr-1 from 1940 to 2009, this is largely related to the increased of harvest index, number of grains m-2 and biological yield, which were achieved through improving stomatal conductance and photosynthetic rate in pre and post-anthesis and reduced in plant height. The nitrogen uptake efficiency (NUpE) was positively associated with nitrogen use efficiency (NUE) in the absence of fertilization. Nitrogen utilization efficiency (NutE) and NUpE were positively associated with NUE in higher N. The modern cultivars (Quartzo, CD 117, BRS Tangará, BRS 220, BRS 208 and BRS Guamirim) were more efficient in the use of nitrogen and more tolerant to low N input compared to the group formed by BRS 179, BR 23, Toropi and Frontana.CNPqConhecer os processos responsáveis pelo avanço do progresso genético do rendimento de grãos é uma etapa essencial para o desenvolvimento de cultivares mais produtivas. Os objetivos do estudo foram: a) Avaliar a duração dos subperíodos de desenvolvimento de cultivares de trigo brasileiros, lançados entre 1940 e 2009, e quantificar a importância de cada fenofase sobre o rendimento de grãos e seus componentes. b) Caracterizar, fisiologica e agronomicamente, cultivares de trigo desenvolvidos entre 1940 e 2009, a fim de identificar critérios de seleção mais efetivos à continuidade do progresso genético de melhoramento no Brasil. c) Caracterizar cultivares antigos e modernos brasileiros, lançados em diferentes décadas, quanto à eficiência do uso do nitrogênio e seus componentes. Dez cultivares de trigo brasileiros, antigos e modernos, foram avaliados em ensaios de competição, em duas safras agrícolas (2010 e 2011); na safra agrícola de 2011 um ensaio foi conduzido em casa de vegetação, com quatro doses de nitrogênio (0, 60, 120 e 180 kg N ha-1). Comparou-se a duração dos subperíodos, caracteres agronômicos e fisiológicos (trocas gasosas) e caracteres da eficiência do uso do nitrogênio (EUN). O melhoramento reduziu a fase de semeadura a antese e aumentou a fase de enchimento de grãos, contribuindo com o aumento da massa de mil grãos. Os genótipos modernos tiveram o subperíodo de espigueta terminal a antese aumentado (0,68 a 1,35 graus dias ano-1) ao longo dos anos, contribuindo com o incremento do número de grãos por espigueta, número de grãos por espiga, peso seco de espiga em antese e índice de fertilidade da espiga. O incremento de rendimento de grãos foi de 29 kg ha-1 ano-1, com um ganho genético de 0,92% ano-1 no período de 1940 e 2009. O progresso genético para rendimento de grãos foi principalmente relacionado ao incremente do índice de colheita, número de grãos e rendimento biológico, que foram alcançados pelo aumento da condutância estomática e da taxa fotossintética em pré e pós-antese e redução da estatura de planta. A eficiência de absorção de nitrogênio (EAN) foi positivamente associada com a eficiência do uso do nitrogenio (EUN) na ausência de adubação nitrogenada. A eficiência de utilização do nitrogenio (EUtN) e a EAN foram positivamente associadas a EUN nas doses elevadas de N. Os cultivares mais recentemente disponibilizados para cultivo (Quartzo, CD 117, BRS Tangará, BRS 220, BRS 208 e BRS Guamirim) foram mais eficientes no uso do nitrogênio e mais tolerantes a baixas doses em comparação ao grupo formado pelos cultivares BRS 179, BR 23, Toropi e Frontana

Nested association mapping and accuracy of predicting genomic breeding value for agronomic and seed composition traits in three interspecific soybean populations

Includes vitaGiven the narrow genetic base of soybean, discovering useful traits in exotic germplasm could increase the diversity in the current elite gene pool. However, it is essential to characterize beneficial alleles from the wild soybean (Glycine soja) to enhance genetic gain. The objective of this study was to investigate grain yield, agronomic traits and seed composition traits using a soybean NAM panel containing crosses between Williams 82 (hub-parent) and three Glycine soja parents (PI464890B, PI458536, and PI522226). Field tests were conducted in Albany, Columbia, Novelty and Rock Port, Missouri for two years, 2016 and 2017, in an augmented incomplete block design with one replication in 2016 and two replications in 2017. The nested association mapping and linkage mapping could identify three major QTL for plant maturity from Glycine soja in Chromosomes 6, 11 and 12 presenting a significant increment in days to maturity. A major QTL for plant height was identified in Chromosome 13 and showed an increase in plant height for lines that carried the wild soybean allele. A significant QTL for grain yield from Glycine soja was detected in Chromosome 17 and showed a positive effect of 166.1 kg ha-1 and yielded an average of 6% more than the Glycine max parent (Williams 82) across environments. Also, we identified 61 and 12 QTLs associated with seed composition traits in the NAM analysis and linkage analysis, respectively. Four QTLs showed pleiotropic effects with soybean seed composition traits. Two QTLs, one on Chromosome 5 and another on Chromosome 15 were associated with the fatty acid profile, explaining 3-18% of the phenotypic variance. The confirmed QTLs for protein and oil cqSeed protein-001 on Chromosome 15 and cqSeed protein-003 on Chromosome 20 were identified. Also, the QTL on chromosome 20 was associated with ten amino acids. However, the allele associated with protein concentration was also responsible for a reduction in amino acid concentration. Another QTL on Chromosome 19 was associated with Cysteine, Methionine, and Leucine and explained 9-30% of the phenotypic variation. Our results reinforce that increasing protein may not increase amino acid concentrations and suggest independent genetic control for protein and sulfur-containing amino acids. In addition to the mapping study, we conducted a genomic prediction study in the NAM panel. Increasing the training population size from 50 to 300 individuals improved prediction accuracy from 0.49 to 0.77 (57% increase) across all traits, with little increment between 300 and 390 individuals (1%). Marker density had little impact on the prediction accuracy across traits, with a significant increment in prediction accuracy up to 1423 markers (18.5%). The training population design Across all families had higher prediction accuracies for all the traits compared with Leave one family out and Within families designs, with prediction accuracies ranged from moderate (0.55) to high (0.75). The NAM panel containing interspecific crosses, successfully predict polygenic traits. Our results showed encouraging prediction accuracies for grain yield (0.55-0.73), which is impressive from crosses originating from wild soybean. In conclusion, training population strategies where population size and multiple families were maximized (Across all families design) produce robust prediction accuracies for yield, maturity, protein, and oil. Genomic predictions might also accelerate genetic gain in pre-breeding efforts using wild soybeans.Includes bibliographical reference

Combining ability of wheat genotypes estimated by multivariate analysis

O objetivo deste trabalho foi estimar capacidades de combinação de genótipos de trigo por meio de análise multivariada, de modo a identificar cruzamentos com desempenho superior. Foram cruzados oito genitores de trigo, na forma de dialelo completo, sem os recíprocos. Os cruzamentos e o avanço de geração foram realizados em 2007 no esquema de semeadura em linha cheia, e os híbridos foram avaliados em 2008, em delineamento de blocos casualizados, com três repetições. Os dados foram submetidos a análise de variância uni e multivariada, análise de componentes principais e análise dialélica parcial e multivariada. Os genitores de melhor desempenho para capacidade geral de combinação para os caracteres do grupo 1 (rendimento de grãos, massa de mil grãos, massa de espiga e número de grãos por espiga) e do grupo 2 (dias da emergência à floração, dias da floração à maturação e estatura de planta) foram as cultivares BRS Guamirim e Fundacep Raízes, respectivamente. Os cruzamentos 'BRS Guamirim' x 'Fundacep Cristalino' (para os caracteres do grupo 1) e 'Abalone' x 'Fundacep Cristalino' e 'Abalone' x 'Fundacep Raízes' (para os caracteres do grupo 2) destacam-se pela capacidade específica de combinação.The objective of this work was to estimate the combining ability of wheat lines using multivariate analysis, in order to identify crossing combinations with superior performance. Eight wheat parental lines were crossed in a complete diallel design without reciprocals. Crosses and advanced generations were obtained in the year 2007 in a full-line sowing system, and the hybrids were evaluated in 2008, in a randomized block design with three replicates. The data were treated using and multivariate , principal component analysis, and partial and multivariate diallel analyses. The cultivar BRS Guamirim was the parental genotype with the best performance for general combining ability for group 1 traits (grain yield, thousand grains weight, spike weight and number of grains per spike), whereas the cultivar Fundacep Raízes was the best for group 2 traits (days from emergence to bloom, days from bloom to maturation, and plant height). 'BRS Guamirim' x 'Fundacep Cristalino' (for group 1 traits) and 'Abalone' x 'Fundacep Cristalino' and 'Abalone' x 'Fundacep Raízes' (for group 2 traits) were the best crossings for specific combining ability

Sowing dates and agronomic performance of soybean cultivars

O objetivo deste trabalho foi avaliar o efeito de épocas de semeadura no desempenho agronômico de cultivares de soja em São Domingos, SC, e indicar as cultivares mais estáveis e adaptadas a cada época. O experimento foi conduzido durante dois anos agrícolas (2008/2009 e 2009/2010), com seis cultivares e quatro épocas de semeadura (15/10, 15/11, 15/12 e 15/1), em delineamento experimental de blocos ao acaso, com três repetições e parcelas com área útil de 3,6 m². A metodologia AMMI (modelos de efeitos principais aditivos com interação multiplicativa) foi utilizada para avaliar o desempenho produtivo das cultivares, e a GGE (genótipo e interação genótipo x ambiente) para avaliar a adaptabilidade e a estabilidade das cultivares nas diferentes épocas de semeadura. Em ambos os anos agrícolas, as semeaduras em 15/10 e 15/11 maximizaram o número de vagens por planta, o número de grãos por vagem, a estatura das plantas, o número de ramos, a massa de mil sementes e, consequentemente, a produtividade de grãos. As cultivares de ciclo médio ou precoce com porte elevado são mais adequadas para semeaduras tardias.The objective of this work was to evaluate the effect of sowing dates on the agronomic performance of soybean cultivars in São Domingos, SC, Brazil, and to indicate stable and adapted cultivars for each sowing date. The experiment was carried out during two crop years (2008/2009 and 2009/2010), using six cultivars and four sowing dates (10/15, 11/15, 12/15, and 1/15), in a randomized complete block design, with threereplicates and a usable plot area of 3.6 m2. The AMMI (additive main effects and multiplicative interaction analysis) method was used to evaluate the yield performance of the cultivars, and the GGE (genotype and genotype‑by‑environment) method to evaluate the adaptability and stability of the cultivars in each sowing date. In both crop years, the sowings on 10/15 and 11/15 maximized the number of pods per plant, the number of grains per pod, plant height, the number of branches, the weight of a thousand seeds, and, consequently, grain yield. Medium or early cycle cultivars, with high plant height, are more adequate for late sowing

Eficiência de uso de nitrogênio em cultivares de trigo pioneiras e modernas

The objective of this work was to characterize Brazilian wheat cultivars, developed in different decades, as to their nitrogen use efficiency, under different availabilities of the nutrient. Ten wheat cultivars, released between 1940 and 2009, were subjected to four nitrogen fertilization rates (0, 60, 120, and 180 kg ha‑1 N), under a controlled environment, in a randomized complete block design, with three replicates. Grain yield increased in 0.54, 0.74, 0.74, and 0.82% per year at the rates of 0, 60, 120, and 180 kg ha‑1 N, respectively. Nitrogen uptake and utilization efficiencies were positively associated with N use efficiency, with strengthening relation under high N availability conditions. Modern cultivars are more efficient in N use and tolerate lower rates of the nutrient in comparison to pioneer cultivars. For the development of more efficient cultivars in N use, wheat‑breeding programs should prioritize the selection of genotypes with higher N uptake, remobilization, and utilization efficiencies.O objetivo deste trabalho foi caracterizar cultivares brasileiras de trigo, desenvolvidas em diferentes décadas, quanto à eficiência de uso de N, sob diferentes disponibilidades do nutriente. Dez cultivares de trigo, lançadas entre 1940 e 2009, foram submetidas a quatro doses de adubação nitrogenada (0, 60, 120 e 180 kg ha‑1 de N), em ambiente controlado, em delineamento de blocos ao acaso, com três repetições. A produtividade de grãos aumentou em 0,54, 0,74, 0,74 e 0,82% ao ano, nas doses de 0, 60, 120 e 180 kg ha‑1 de N, respectivamente. As eficiências de absorção e de utilização de N estiveram positivamente associadas à eficiência de uso do nitrogênio, com estreitamento na relação em condições de alta disponibilidade de N. As cultivares modernas são mais eficientes no uso do N e toleram doses mais baixas do nutriente, em comparação às cultivares pioneiras. Para o desenvolvimento de cultivares mais eficientes no uso de N, os programas de melhoramento genético de trigo devem priorizar a seleção de genótipos com maiores eficiências de absorção, remobilização e utilização de N

Agronomic performance of wheat cultivars in response to nitrogen fertilization levels=Desempenho agronômico de cultivares de trigo em resposta a doses de adubação nitrogenada

The release of wheat cultivars with different nutritional demands and yield potential hinders generalized recommendations for nitrogen fertilization. This study was designed to evaluate the effects of different nitrogen fertilization levels (0, 60, 120 and 180 kg ha-1 of N) on the agronomic performance of six wheat cultivars (Triticum aestivum L.) in two harvests. A randomized block factorial design with three replications was used. The response to fertilization levels was evaluated through AMMI (Additive Main effects and Multiplicative Interaction) and GGE (Genotype main effects and Genotype x Environment interaction) biplot graphic methodologies and polynomial regression. There was genetic variability in response to nitrogen fertilization in the cultivars studied. The biggest increases in yield were observed under a more suitable water regime. The higher performance of yield components was associated with higher nitrogen fertilization levels.<br><br>O lançamento de cultivares, com diferentes exigências nutricionais e potencial produtivo inviabilizam recomendações generalizadas de adubação nitrogenada para a cultura do trigo. O objetivo do presente trabalho foi de avaliar os efeitos de doses de adubação nitrogenada (ausência de fertilização, 60, 120 e 180 kg ha-1 de N) sobre o desempenho agronômico de seis cultivares de trigo (Triticum aestivum L.), em duas safras agrícolas. O delineamento experimental foi em blocos ao acaso em esquema fatorial, com três repetições. A resposta às doses empregadas foi avaliada através das metodologias em gráfico biplot AMMI (Additive Main effects and Multiplicative Interaction) e GGE (Genotype main effects and Genotype x Environment interaction) e regressão polinomial. Há variabilidade genética quanto à resposta a adubação nitrogenada, no conjunto de cultivares avaliados. Os maiores incrementos em produtividade ocorreram em condições mais adequadas de precipitação pluvial. O maior desempenho dos componentes do rendimento foram associados às maiores doses de adubação nitrogenada

Identifying superior spring wheat genotypes through diallel approaches

Abstract Diallel crosses enable plant breeders taking decisions concerning the parental choice for developing new varieties. Recently, a large number of methodological models have been reported. The objective of this study was to investigate the relationship between different methods of diallel analysis and their associations with grain yield performance in wheat (Triticum aestivum L.) segregating populations. In this study, four methods of diallel analysis were used to estimate the general (GCA) and specific (SCA) combining abilities: (a) Griffing, (b) Multivariate analyses of diallel crosses, (c) Restricted Maximum Likelihood / Best Linear Unbiased Prediction (REML/BLUP) and d) Genotypes and Genotypes x Environments biplot (GGE biplot). Six wheat cultivars were hybridized in a partial diallel scheme and later evaluated in the along with 15 F 2 segregating populations. Griffing and REML/BLUP analysis produced equivalent results for GCA and SCA and are meaningful for identifying superior inbred lines. Multivariate diallel analysis suggested the best crosses for simultaneous improvement of traits. GGE biplot method is an effective method for visual comparisons of GCA and SCA effects. Conventional and innovative methods of diallel analysis are useful, complementary and should be applied in the selection of parents and superior crosses