Vanderlei da Rosa Caetano

Genetic Basis of Stay-Green Trait in Bread Wheat

ABSTRACT The stay-green trait is responsible for the preservation of green coloration in the stem and leaf, during physiological maturity. It has also been shown to play an important role in the increase of grain size. The knowledge of the inheritance of this trait can constitute valuable information to plant breeders in the developing new wheat (Triti-cum aestivum L.) varieties. This study was conducted in two environments, during the years of 1997 and 1998, to verify the genetic basis of the stay-green trait among crosses of four different genotypes in the field and three in the greenhouse. The analysis was based on three fixed (P1, P2 and F1) and three segregating (F2, BC1F1 and BC2F1) generations. Means and variances were computed for every generation for each cross and the nature of the gene and its effects were estimated. Change in stem color was used as the criterion for the stay-green trait in three phases of development in wheat, based on scores obtained from visual analysis, on a scale of 1 to 10. The results presented in the 2nd observation phase, suggest that the stay-green trait is controlled by only one gene with two alleles and gene activity with high predominance of additive effects and to a lesser degree, a partial dominance for stay green.

Análise de trilha para os componentes de rendimento de grãos em trigo

The purpose of this work was to estimate the effect of the ear number per plant, number of seeds per ear, seed weight, size of the ear and spikiest number per ear in relation to the grain yield through its correlation coefficients and its decomposition by the path analysis. The genotypes were obtained through the advances generation in the years from 1999 to 2001, using two sowing dates per year, in the warm and cold season, in the field and in green-house conditions, at the Federal University of Pelotas, RS. The experiment was conducted as a randomized complete block design with five replications. The characters spikiest number for spike and hectoliter weight were identified by the path analysis, as being the one of high potentiality for selection of superior genetic constitutions for seed yield seeds.

Caracteres relacionados com a resistência ao acamamento em trigo comum

Grain yield is affected by plant lodging, and this is a serious problem mainly for tall wheat cultivars. A field trial was conducted during 1999 growing season to investigate the variability for some morphological traits associated to lodging resistance in 14 wheat genotypes. It was found variability for all traits evaluated. Values of lodging resistance coefficient, plant height, length of peduncle and culm index were highly correlated with lodging resistance. These traits can be recommended for lodging resistance indirect selection. Among genotypes evaluated, line TB 951 showed the best performance for all traits related to lodging resistance. So, that line can be indicated as an excellent lodging resistance source in bread wheat.

Análise dialélica para tolerância ao vírus-do-nanismo-amarelo-da-cevada em cultivares brasileiras de trigo

Six Brazilian bread wheat cultivars differing in tolerance to barley yellow dwarf virus (BYDV) were crossed according to a diallel design, to determine general and specific combining ability. ABYDV isolate transmitted by Rhopalosiphum padi (L.) was inoculated in plants when seedlings had two leaves. Ten days after anthesis each plant was examined receiving a score according to its symptom severity. Data were evaluated according to Griffing method, fixed model and method two. Heterosis was evidenced, related to the addictive effects of complementary genes. Cultivars BR 34 and BR 35 showed the best values of general combining ability (GCA). They are recommended as parents in wheat breeding programs to obtain tolerant genotypes to BYDV.

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(

Prediction of parental combination for introduction of stay-green associated loci in wheat

In wheat, the increase of yield and stability associated traits can be achieved by combining parents containing the stay-green trait and favorable alleles for grain yield. The aim of this work was to analyze the genetic dissimilarity between wheat lines from stay-green and synchronized maturation groups and elite cultivars. Moreover, to propose promising combinations seeking the selection of high-grain yield and high bread-making quality genotypes containing stay-green trait. The experiment was conducted in a randomized block design with three replications in 2003, 2004, and 2005, using sister-lines with the presence and absence of stay-green trait and elite cultivars. Genetic variability exists among wheat strains from the synchronized stay-green maturation group and elite cultivars. Genotypes of maturation group stay-green obtained an average performance superior to the synchronized group. Crosses between stay-green lines and the CEP 29 and BRS 177 cultivars are promising in the selection of genotypes carrying the stay-green trait with high yield and bread-making quality.

Toxicidade do alumínio e efeito do ácido giberélico em linhas quase isogênicas de trigo com o caráter permanência verde e maturação sincronizada

O objetivo deste trabalho foi avaliar linhas quase isogenicas de trigo com o carater permanencia verde e de maturacao sincronizada quanto a tolerância ao aluminio e a sensibilidade ao acido giberelico (AG3). O experimento foi conduzido no Laboratorio de Duplo-haploides e Hidroponia da FAEM/UFPel, em delineamento de blocos ao acaso, com parcelas subdivididas com tres repeticoes, atraves do teste simultâneo utilizando solucao nutritiva com concentracoes de 10mg L-1 de Al3+ e 100mg L-1 de AG3. Foram determinados: a insercao da 1a folha, o comprimento da 1a folha, a insercao da 2a folha, comprimento da 2a folha, diferenca da insercao entre a 1a e 2a folha, estatura de plântula, estatura de planta, area foliar, area radicular e o crescimento de raiz. Os caracteres estatura da plântula, insercao da 1a folha e comprimento da 2a folha foram os mais expressivos para a selecao de individuos com estatura reduzida atraves da reacao do AG3. O grupo do carater permanencia verde apresentou maior insensibilidade a acao do AG3, enquanto o grupo de plantas sincronizadas proporcionou maior tolerância ao Al3+. Contudo, existe possibilidade de selecionar linhas quase isogenicas dentro do grupo permanencia verde com tolerância ao Al3+ e insensibilidade ao AG3 atraves da tecnica de cultivo hidroponico com solucao nutritiva em ambiente controlado.