Roni de Azevedo

Correlações canônicas: II - análise do rendimento de grãos de feijão e seus componentes

Thirty two bean genotypes (Phaseolus vulgaris L.) were evaluated in Lages/SC, Brazil, on the influence of seven characters of agronomic importance on the production of grains per unit of area. The experiment, in randomized blocks with four repetitions, was driven in the off season period in the agricultural year of 1995/96. This work aimed to estimate the intensity the association between the primary and secondary components of grain yield. The first group of variables (primary) was constituted by the number of grains per pod, number of pods per plant and the weight of a thousand grains. The second group (secondary) consisted of number of days from emergency to flowering, number of days from emergency to harvesting point, plant stature and the first pod insertion point. For the analysis of canonical correlations, the importance of secondary agronomic characters was evident in the traits number of pods per plant and grains per pod and also the influence of both on the final grain yield. Therefore, the coefficients of canonical correlations indicate that, in programs bean genetic improvement programs, to increase the production of grains one should select plants with larger number of pods per plant in order to obtain plants with higher stature and longer cycle.

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.