Igor Pires Valério

Adaptabilidade e estabilidade em aveia em ambientes estratificados

Twenty oat genotypes (Avena sativa L.) were evaluated for grain yield in the crop year of 2001 and 2002 in nine different locations in Parana, Rio Grande do Sul and Sao Paulo states, Brazil. The objectives of this work were to obtain adaptability and stability parameters estimates in favorable and unfavorable environments with and without fungicide application. The methodology of EBERHART & RUSSELL (1966) was applied. The significance for years, genotypes, fungicides and locals indicated a differential behavior of genotypes in favorable and unfavorable environments with and without fungicide application. Data analysis shows that fungicide application and the favorable and unfavorable environment affected intensely the parameters of adaptability (b1) and stability (s2di), indicating that these estimates must be performed in stratified environmental conditions, despite the fact that no ideal biotype was found, as predicted by the adopted model.

Morphological and AFLP markers for describing genetic relationships among white-oat genotypes

The use of different genetic dissimilarity indicators can help in both the selection of crop improvement strategies and as artificial crosses. The objectives of this work were to estimate the genetic dissimilarity among seven oat genotypes (Avena sativa L.) through molecular (dg) and morphological (dm) markers. Data were obtained from two experiments carried out in Capao do Leao County, RS, Brazil, in 2000. The estimated correlation coefficient (r = 0.33) indicated a low association between dg and dm estimates. The genotypes with similar pedigrees (UPF 16 and UPF 17), with a bootstrapping value of 82.7%, performed the most consistent group (dg) and clustered more closely in both techniques (dg and dm). However, genotypes with similar pedigree clustered in distant groups. Both dissimilarity estimates need to be used in order to obtain a more reliable choice of dissimilar parents, with higher probability of developing promising base populations.

Variabilidade fenotípica de caracteres adaptativos da aveia branca (Avena sativa L.) em cruzamentos dialélicos

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.

Caráter stay-green e produtividade de grãos em trigo

ABSTRACTSTAY-GREEN TRAIT AND WHEAT GRAIN YIELD The stay-green trait is one of the factors that can aid the breeder in obtaining higher yieldingplants due to a delay in leaf senescence, favouring grain filling. The objective of this study was to evaluatethe performance of different wheat lines with and without the stay-green trait and investigate if longergreen period; foster an increment of grain yield. The field experiment was conducted in randomizedcomplete block design with three replications in two crop years. Genetically superior lines facilitate thebenefits of the stay-green trait for grain yield. The stay-green trait promotes yield stability under differentenvironments.Key words: Triticum aestivum L., green permanence, plant breeding.( 1 ) Recebido para publicacao em 5 de dezembro de 2006 e aceito em 5 de julho de 2007.( 2 ) Departamento de Estudos Agrarios - Agronomia/Universidade Regional do Noroeste do Estado do Rio Grande do Sul (Unijui),98700-000 Ijui (RS). E-mail: jose.gonzales@unijui.edu.br(

Correlação de acamamento com rendimento de grãos e outros caracteres de interesse agronômico em plantas de trigo

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 Agropecuario da Palma, Capao do Leao/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 at 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.

Early generation selection strategy for yield and yield components in white oat

Several studies have searched for higher efficiency on plant selection in generations bearing high frequency of heterozygotes. This work aims to compare the response of direct selection for grain yield, indirect selection through average grain weight and combined selection for higher yield potential and average grain weight of oat plants (Avena sativa L.), using the honeycomb breeding method. These strategies were applied in the growing seasons of 2001 and 2002 in F3 and F4 populations, respectively, in the crosses UPF 18 CTC 5, OR 2 ´ UPF 7 and OR 2 ´ UPF 18. The ten best genetic combinations obtained for each cross and selection strategy were evaluated in greenhouse yield trials. Selection of plants with higher yield and average grain weight might be performed on early generations with high levels of heterozygosis. The direct selection for grain yield and indirect selection for average grain weight enabled to increase the average of characters under selection. However, genotypes obtained through direct selection presented lower average grain weight and those obtained through the indirect selection presented lower yield potential. Selection strategies must be run simultaneously to combine in only one genotype high yield potential and large grain weight, enabling maximum genetic gain for both characters.