[Show abstract][Hide abstract] ABSTRACT: The black oat (Avena strigosa Schreb) is commonly used for forage, soil cover, and green manure. Despite its importance, little improvement has been made to this species, leading to high levels of genotypic disuniformity within commercial cultivars. The objective of this study was to evaluate the efficiency of different doses of gamma rays [(60)Co] applied to black oat seeds on the increase of genetic variability of agronomic traits. We applied doses of 0, 10, 50, 100, and 200 Gy to the genotype ALPHA 94087 through exposure to [(60)Co]. Two experiments were conducted in the winter of 2008. The first aimed to test forage trait measurements such as plant height, dry matter yield, number of surviving tillers, and seedling stand. The second test assessed seed traits, such as yield and dormancy levels. Gamma irradiation seems not to increase seed yield in black oats, but it was effective in generating variability for the other traits. Tiller number and plant height are important selection traits to increase dry matter yield. Selection in advanced generations of mutant populations can increase the probability of identifying superior genotypes.
[Show abstract][Hide abstract] ABSTRACT: The goal of this work was to determine the combining ability of three white oat parental genotypes (UPF 18, URS21 and URS 22) and to estimate the heterosis of F1 hybrids in two conditions, with and without water stress. The results indicate a large effect of the environment on the evaluated characters (cycle, leaf area, plant stature, grain yield per plant, main panicle weight and number of grains of the main panicle). The condition without stress was the most efficient for the selection of superior genotypes. Based on the general and specific combining ability, the cultivar URS 22 was shown to be indicated for cycle and stature reduction, while UPF 18 lead to increases in leaf area, main panicle weight and number of grains of the main panicle. The specific cross URS 22 x URS 21 was the best for the selection of superior genotypes.
[Show abstract][Hide abstract] ABSTRACT: The area sown to black oat in Brazil has experienced a dramatic growth as a consequence of the expansion of minimum tillage, crop rotations and crop-livestock systems. This growth was not accompanied by research work providing data on the relevant agronomic traits from this forage grass, which would eventually lead to the creation of new varieties meeting the growers' demands. This work evaluated traits related to forage production and seed dormancy in black oat populations originating from artificial breeding between pure lines derived from the "Preta Comum" variety and commercial varieties from this species. Two experiments were carried out during the winter of 2008, at the Capão do Leão, Rio Grande do Sul State, one to assess forage production traits and the second to measure seed traits such as yield and dormancy levels. The results showed that artificial breeding enhanced genetic variability through improvement on the expression of forage traits, seed yield and dormancy levels. In relation to the former, plant stand was highly associated to dry matter production during the early stages of seedling development and establishment, while tiller production remained the major component explaining biomass production later stages of forage production. Artificial breeding produced large differences on seed-related traits such as yield and dormancy level, suggesting the existence of adequate levels of variability for these traits among the parent lines.
[Show abstract][Hide abstract] ABSTRACT: The objectives of this work were to determine the grain yield adaptability and stability of ten wheat genotypes (Triticum aestivum L.), contrasting for the character tillering potential, conducted in different seeding densities. The experiments were conducted in the years 2005, 2006 and 2007 in Capão do Leão -RS and in Pato Branco-PR and Ijuí-RS in the year 2007. A split-plot design was used considering the genotype as the plot and seeding density as the sub-plot. The seeding densities used were 50, 200, 350, 500 and 650 viable seeds m-2. The analyses of adaptability and stability were performed using the method proposed by Eberhart and Russell. The changes in seeding density and location intensely influenced the adaptability and stability parameters for grain yield. Genotypes adapted to various seeding densities were found (FUNDACEP 29 - except for 650 seeds m-2), as well as those with specific adaptability and a predictable performance only in favorable (CD 114) and unfavorable (CD 108) environments, indicating the need of an adequate fitting of seeding density to the performance predictability for grain yield in wheat.
[Show abstract][Hide abstract] ABSTRACT: Plant breeding is based on the pursue of an amplification of genetic variability through planned crosses. Thus, it is of fundamental importance to study the formed populations, in order to predict the potential of different parental combinations, allowing a higher selection efficiency for the desired trait, optimizing genetics gains. Thus, the objective of this work was to observe the phenotypic variability of the characters plant stature, vegetative cycle and reproductive cycle in F2 generation and to predict the best combinations to obtain superior genetic constitutions. Therefore, five oat genotypes (UPF 16, UPF 18, UFRGS 7, UFRGS 17 and URPEL 15) were crossed in a diallelic format, without reciprocal crosses, for the development of F2 populations. To analyze population variability, the following parameters were used: mean, variance and asymmetry of frequency distribution. The crosses UPF 16 x UFRGS 17 and UFRGS 17 x URPEL 15 produced a large amount of plants with shorter stature. For the character vegetative cycle, UPF 16 x UPF 18, UPF 16 x UFRGS 7, UPF 16 x UFRGS 17, UPF 16 x URPEL 15, UFRGS 7 x UFRGS 17 and UFRGS 7 x URPEL 15 were the crosses that produced short cycle plants. UPF 16 x UFRGS 17 and UPF 16 x URPEL 15 produced a large number of long-cycled progenies.
[Show abstract][Hide abstract] ABSTRACT: The knowledge of how the agronomical traits are correlated in segregating populations is of primary importance for plant breeders, specially when one considers indirect selection through a character easily measurable or with high heritability correlated to the trait of interest with lower heritability. Agronomical traits in F2 and F3 generations of four wheat crosses, were evaluated on 2004 agricultural year in the Centro Agropecuário da Palma, of the Centro de Genômica e Fitomelhoramento - FAEM/UFPel, located in Capão do Leão country in Rio Grande do Sul State. The present work had the objectives to estimate for evaluated traits: a) genotypic, phenotypic and environmental correlation coefficients between the traits; and b) path coefficients for grain yield. For all populations, the single correlations indicated that the selection of higher yielding plants can be performed by indirect selection for number of fertile tillers per plant. The path analysis showed that it was possible to identify the indirect effect of the trait number of fertile tillers the as cause of the correlation between other traits (ear length x grain yield, spikelet number per ear x grain yield and number of ear grain x grain yield). Thus suggesting that the number of fertile tillers is the major trait to select for in order to obtain gains on grain yield.
[Show abstract][Hide abstract] ABSTRACT: The selection in yield primary components and lodging resistance with goal of increasing grain yield can represent efficient strategies for optimizing genetic gain in wheat. In this sense, the objective of the present work was to detect characters that enable the identification of high grain yield potential and lodging resistant genotypes through the use of indirect selection. The experiment was conducted at the Centro Agropecuário da Palma, Capão do Leão/RS, consisting of nineteen wheat genotypes arranged in random block design with three replications. In this work conditions the hectoliter weight can be efficiently used through indirect selection aiming increasing grain yield, average grain weight, number of grains per ear and ear weight. The character ear weight showed high indirect effect on grain yield and can be used for indirect selection due to its ease of measurement. The line TB 951 is indicated as an excellent source for lodging resistance in wheat, and can contribute to increase ear length, number of spikelets per ear, ear weigh and number of grain per ear.
[Show abstract][Hide abstract] ABSTRACT: Oat crown rust is the most important disease for the oat crop, occurring in practically all the areas where oat is cultivated. The most indicated form of control for this disease is the use of resistant cultivars. However, for the durable resistance to be acquired, it is necessary to know the genetics of resistance to crown rust in oats. Thus, the objective of this work was to determine the type of inheritance of resistance to three Puccinia coronata f. sp. avenae Fraser & Led., isolates (collected in southern Brazil) in brazilian white oat genotypes. To determine the inheritance of resistance to each one of three isolates,F2 populations were used generated through artificial crosses, between resistant (R) and susceptible (S) and between resistant genotypes (R). Thus, F2 populations from the following artificial crosses: i) URPEL 15 (R) x UFRGS 7 (S), UPF 16 (R) x UFRGS 7 (S) and URPEL 15 (R) x UPF 16 (R), were used to determine the inheritance of resistance to isolate one (1); ii) URPEL 15 (R) x UFRGS 7 (S), UPF 18 (R) x UFRGS 7 (S) and URPEL 15 (R) x UPF 18 (R), to determine the inheritance of resistance to isolate two (2); iii) URPEL 15 (R) x UFRGS 7 (S) and URPEL 15 (R) x UPF 18 (S), to determine the inheritance of resistance to isolate three (3). The obtained results indicate that the genotype URPEL 15 present dominants genes for resistance to the three oat leaf rust isolates evaluated, the cultivar UPF 16 presents a recessive gene for resistance to isolate 1 and the cultivar UPF 18 has a recessive gene of resistence to isolate 2. Also, the resistance genes presented by genotypes URPEL 15, UPF 16 and UPF 18, segregate in an independent manner.
[Show abstract][Hide abstract] ABSTRACT: A seleção indireta visando ao incremento no rendimento de grãos pelos seus componentes primários bem como a resistência ao acamamento podem representar estratégias eficientes a serem adotadas para otimização do ganho genético em trigo. Nesse sentido, o objetivo do trabalho foi evidenciar caracteres que possibilitem identificar genótipos de elevado rendimento de grãos e resistentes ao acamamento através de seleção indireta. O experimento foi conduzido no Centro Agropecuário da Palma, em Capão do Leão/RS, utilizando dezenove genótipos de trigo em delineamento de blocos ao acaso, com três repetições. Nas condições deste estudo, o peso hectolítrico pode ser empregado de maneira eficiente na seleção indireta, visando ao incremento no rendimento de grãos, no peso médio de grãos, número de grãos por espiga e no peso de espiga. O caráter peso de espiga evidenciou elevado efeito indireto sobre o rendimento de grãos, podendo ser empregado na seleção indireta pela facilidade de mensuração. A linhagem TB 951 é indicada como excelente fonte de resistência ao acamamento em trigo, podendo contribuir para elevar o comprimento de espiga, o número de espigueta por espiga, o peso de espiga e o número de grãos por espiga.