RESUMO
Despite the continuous breeding that has been conducted with asparagus (Asparagus officinalis L.) since the beginning of the last century, there is little information on parameters for predicting direct and indirect selection response. Yield traits for blanched asparagus production were studied along a two-year period in a half-sib family population planted in Zavalla, Argentina. Half-sib family mean heritability values were low for total yield and marketable spear number (0.31 and 0.35), intermediate for marketable yield and total spear number (0.55 and 0.64), and relatively high for spear diameter and spear weight (0.75 and 0.74). An average increase in marketable yield of 15.9% is expected after each cycle of selection of the top 5% of the families. Total yield failed to express significant genetic correlations with any of the yield components; meanwhile marketable yield showed highly significant relations with market spear number (0.96) and spear weight (0.89). Indirect selection response over yield components (CRx) failed to be advantageous over direct selection (Rx), since the ratio CRx/Rx was always equal or below unity.
Assuntos
Asparagus/genética , Cruzamento , Característica Quantitativa Herdável , Seleção Genética , Asparagus/fisiologia , Modelos Genéticos , FenótipoRESUMO
To estimate the heritability values of characters frequently used as selective criteria, 32 half-sib families obtained from selected plants of three populations of the asparagus variety Argenteüil were evaluated in a randomized complete block design. The following characters were measured: days to emergence of the first spear, number and diameter of spears, number of stalks, plant height and average weight. The values of realized heritability were estimated and were compared with those obtained by the parent-offspring regression method. Phenotypic correlation coefficients between the different variables were significant. The values of realized heritability for most of the variables were moderate to high (between 0.18 and 0.68), except for days to emergence; lower values were obtained by the regression method. As there was a high degree of heritability, additive genetic factors contributed significantly to the genetic variance, which would allow the selection of phenotypically superior plants for asparagus improvement projects.