Components of grain yield in wheat and its direct and indirect effects on productivityUsing path analysis it is possible to evaluate the relationships between characters and decompose the correlation into direct and indirect effects. The objective of this study was to estimate genotypic correlations and decompose the direct and indirect effects of yield components on grain yield of wheat cultivars. The experiment was conducted in 2008, in the experimental field of the Cooperativa Central de Pesquisa Agrícola (COODETEC) in Palotina, PR, Brazil. The experiment was arranged in a randomized block design, with three replications. The characteristics evaluated were: ear size, number of spikelets per spike, number of grains per spike, number of spikes per meter, thousand grain weight and grain yield. The results were subjected to analysis of variance and path analysis. The variance analysis showed differences between genotypes, indicating the presence of genetic variability for traits. Indirect selection via number of grains per spike, taking into account the thousand grain weight is the best strategy for obtaining superior genotypes in grain yield.

Wheat (Triticum aestivum) is one of the most important food staples in the south of Brazil. Understanding genetic variability among the assortment of Brazilian wheat is important for breeding. The aim of this work was to molecularly characterize the thirty-six wheat cultivars recommended for various regions of Brazil, and to assess mutual genetic distances, through the use of microsatellite markers. Twenty three polymorphic microsatellite markers (PMM) delineated all 36 of the samples, revealing a total of 74 simple sequence repeat (SSR) alleles, i.e. an average of 3.2 alleles per locus. Polymorphic information content (PIC value) calculated to assess the informativeness of each marker ranged from 0.20 to 0.79, with a mean of 0.49. Genetic distances among the 36 cultivars ranged from 0.10 (between cultivars Ocepar 18 and BRS 207) to 0.88 (between cultivars CD 101 and Fudancep 46), the mean distance being 0.48. Twelve groups were obtained by using the unweighted pair-group method with arithmetic means analysis (UPGMA), and thirteen through the Tocher method. Both methods produced similar clusters, with one to thirteen cultivars per group. The results indicate that these tools may be used to protect intellectual property and for breeding and selection programs.

The objectives of this study were to investigate the pattern of genotype environment interaction and identify megaenvironments (ME), essential test locations, and suitable genotypes for each ME. The genotype plus genotype by environment interaction (GGE) biplot and additive main effects and multiplicative interaction analysis (AMMI) were used to demonstrate the potential of using a graphical biplot to analyze the genotype by environment interaction (GEI) in data of multienvironment trials (MET). These trials of the Central Cooperative Agricultural Research (COODETEC) evaluated 36 advanced breeding lines and 27 check cultivars for 3 years (2008–2010) at 12 test locations. Yield data were analyzed using the genotype plus GGE and AMMI biplot methods. The test environments were classified into two ME (i.e. ME1: Castro, Guarapuava, Não‐Me‐Toque, Abelardo Luz, and Cachoeira do Sul; and ME2: Campo Mourão, Dourados, Palmital, Palotina, Ponta Porã, and Rolândia. In ME1, the locations Guarapuava, Cachoeira do Sul, and Abelardo Luz were classified as ideal, while in ME2, Ponta Porã, Dourados and Palotina were close to ideal. Guarapuava was the essential test location in ME1; however the identification of an essential test location in ME2 was unclear. Superior cultivars and advanced lines were identified in both ME that could be valuable for spring wheat (Triticum aestivum L.) improvement or cultivars released.

The aim of this study was to evaluate the genetic diversity of the wheat germplasm using high-density genotyping with SNP markers. A set of 211 wheat varieties genotyped with 35,142 SNP markers were used in the experiment. Genetic distances ranged from 0.013 to 0.471, with the highest frequency of distances varying between 0.31 and 0.40. In the cluster analysis by the UPGMA method, 81% of the varieties were clustered in three groups. Genetic variability in the Brazilian wheat germplasm has remained constant for over 70 years. Mean genetic distances among the varieties developed in each decade ranged from 0.33 to 0.34. A trend of genetic distance between genotypes from different eras has been observed over time as a result of breeding. Results described in this study can help Brazilian wheat breeders to manage more adequately genetic variability in the Brazilian wheat germplasm.

Resumo -Este trabalho avaliou genótipos de trigo em condições de escassez de água inoculados com Azospirillum brasilense e Herbaspirillum seropedicae, com e sem adubação nitrogenada. Para tanto, amostras para determinação do conteúdo relativo de água na folha (CRA) e do índice de estabilidade da membrana (IEM) foram coletadas no 1º e 8º dias de uma restrição total de água no estágio de emborrachamento. Além disso, os parâmetros de biomassa, nitrogênio total (NT) e produtividade foram determinados na colheita. Como resultado, os genótipos mostraram um desempenho distinto. Os dados de CRA e IEM revelaram que a inoculação de A. brasilense e H. seropedicae são capazes de conduzir o genótipo CD 120 à tolerância à seca. Além disso, o índice de grãos foi melhorado em todas as condições em que H. seropedicae estava presente em ambos os diferentes regimes de água. O H. seropedicae inoculado juntamente com adubo nitrogenado também aumentou o rendimento de grãos sob o regime de escassez de água. Além disso, A. brasilense inoculado com adubo nitrogenado foi capaz de melhorar a massa de 1000 grãos de plantas sob escassez de água. O cultivar Frontana exibiu a capacidade de manutenção do IEM e CRA apenas quando H. seropedicae ou ambas as bactérias mais adubo nitrogenado foram aplicados, no entanto, esta cultivar não apresentou diferenças em termos de massa fresca e seca da parte aérea e radicular, NT ou produtividade. Estes resultados apontaram H. seropedicae como promissora para inoculação em cereais e o CD120 como um bom modelo de planta para estudar a interação de plantas e bactérias.Palavras-Chave -status hídrico, associação planta-bactéria, rizobactérias. Abstract -This work evaluated wheat genotypes under water deficit inoculated with Azospirillum brasilense andHerbaspirillum seropedicae, with and without nitrogen fertilization. Samples of the plants were collected to evaluate its relative water content (RWC) and membrane stability index (MSI) at the 1 st and 8 th day of total water restriction at the booting stage. The plant biomass, total nitrogen (TN) and grain yield were determined at harvesting. The genotypes showed different performances. According to the results of RWC and MSI, inoculation with A. brasilense and H. seropedicae can make the cultivar CD-120 more tolerant to drought. Grain index was improved with H. seropedicae in all conditions and water regimes. H. seropedicae with nitrogen fertilization increased grain yield under water deficit. A. brasilense with nitrogen fertilization improved the 1000-grain weight of plants under water deficit. The cultivar Frontana maintained its cellular integrity and RWC with nitrogen fertilization combined with H. seropedicae and with both bacteria, however the shoot and root fresh and dry weights, TN and yield of this cultivar showed no differences. These results show the inoculation with H. seropedicae as promising to cereals, and the cultivar CD-120 as a good plant model to study plant-bacteria interaction.