Oito ciclos de seleÃÃo recorrente visando à resistÃncia à mancha-angular no feijoeiro / Eight cycles of recurrent selection aimed at resistance to angular leaf spot in common bean

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

This work was carried out with the objective of evaluating both the genetic progress after eight cycles of phenotypical recurrent selection for resistance to angular leaf spot in bean plants and the indirect responses for both productivity and grain types. The base population was obtained from partial diallelic crossing of seven carioca-type grain lines (Carioca MG, CI-140, CI-128, ANPAT 8.12, IAPAR 81, ESAL 693 and PÃrola), and ten resistance sources to Pseudocercospora griseola (Sacc.) Crous &Braun (2006) (AN 512561, AND 277, Ouro Negro, Compuesto Negro Chimaltenango, CAL 143, MAR 2, MAR1, G 5686, MA 4.137 and Jalo). The plants most resistant to the pathogen were selected in the F2 (S0) generation of the populations (C-0). The best S0:1 plants that presented carioca-type grains were intercrossed to obtain cycle I (C-I). Similar procedure was used in order to obtain cycles II through VIII. In each recurrent selection cycle, besides selecting the best plants to both recombine and obtain the next cycle, plants were phenotypically selected for progenies evaluation in experiments carried out in Lavras-MG, Brazil. A simple-lattice design was used. âCarioca MGâ (susceptible to the pathogen) and âPÃrolaâ (tolerant) cultivars were used as check. The following traits were evaluated: resistance to the pathogen (evaluated by means of a grading scale â 1 through 9 â where 1 stands for symptoms absence, and 9 for totally attacked plants); grain type according to carioca pattern; grains productivity. The genetic progress towards resistance to the pathogen was estimated from the general means of the progenies of each selective cycle in relation to the Carioca MG, the susceptible check. No genetic progress was found to resistance to angular leaf spot, probably because the equation determining coefficient was too low. The average progenies resistance was found to be equivalent to that of the PÃrola cv, considered to be tolerant, what shows that the original population had already a high level of resistance. The indirect gain in grains productivity was 2,3%, and 2,5% for grains type per selective cycle.

ASSUNTO(S)

pseudocercospora griseola genetic progress phaseolus vulgaris produtividade de grÃos grain yield resistÃncia a doenÃas progresso genÃtico herdabilidade disease resistance phaseolus vulgaris pseudocercospora griseola heritability genetica vegetal tipo de grà grain type

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