RESUMEN
Con el objetivo de evaluar la vida productiva de cerdas de las razas Large White (LW), Landrace (LR) y sus cruces recíprocos, se analizaron 2444 registros de prolificidad (TAN) y peso acumulado de la camada al nacer (PAN). Los registros de las cerdas provinieron de una granja comercial ubicada en el estado Yaracuy. Los datos fueron ajustados por mes, período de años y número de parto. Para el análisis final se agruparon los años de nacimiento de las cerdas en dos períodos: 1986 - 1998 y 1999 - 2005. Se consideraron las cerdas con la oportunidad de tener al menos tres partos. Se realizaron análisis de varianza por el procedimiento de máxima verosimilitud restringida. Los efectos incluidos en el análisis fueron: grupo racial de cerda (GRC: 1, ,4), período de nacimiento de la cerda (PN: 1, 2), mes de nacimiento de la cerda (MN: 1, , 12), GRC*MN y la edad al primer parto como covariable. Se obtuvieron promedios ajustados y no ajustados de 39,27 y 39,3 lechones; y 59,5 kg y 59,58 kg para TAN y PAN, respectivamente. Las cerdas del grupo racial LR*LW (42,69 lechones y 63,32 kg) y LW (41,44 lechones y 62,57 kg) resultaron superiores (P<0,01) en TAN y PAN, respectivamente. Hubo efecto estadístico significativo de PN, MN y GRC*MN. La heterosis fue significativa para (TAN) con un valor de 5,9%. Se concluye que las cerdas puras o cruzadas cuyo genotipo posee alelos provenientes de madres de la raza LW, son superiores para los caracteres evaluados.
With the purpose of evaluating the productive life of Large White (LW) and Landrace (LR) sows and their reciprocal crosses, 2.444 records of prolificacy (TAN) and aggregated weight of the litter at birth (PAN) were analyzed. The sow records came from a commercial farm located in the State of Yaracuy, Venezuela. The data were adjusted by month, period of year, and farrowing number. For the final analysis, the years of birth of the sows were grouped into two periods: 1986- 1998 and 1999-2005. Sows with a chance of at least delivering three farrowings were considered. An analysis of variance (ANOVA) by the restricted maximum likelihood procedure was performed. The effects included in the analysis were: breed group of the sow (GRC: 1 4), birth period of the sow (PN: 1, 2), month of birth of the sow (MN: 1 12), the GRC*MN interaction, and the age at first farrowing as covariate. The adjusted and non-adjusted TAN averages obtained were 39.27 and 39.3, respectively; and the adjusted and nonadjusted PAN averages were 59.5 and 59.58 kg, in that order. The sows of LR*LW (42.69 piglets and 63.32 kg) and LW (41.44 piglets and 62.57 kg) breed group were higher (P<0.01) in TAN and PAN, respectively. There was a statistically significant effect of PN, PM, and GRC*MN. Heterosis was significant for TAN, with a value of 5.9%. It is concluded that purebred sows and their crosses whose genotype have alleles from mothers of the LW breed, are superior for the characteristics assessed in this research.
RESUMEN
Com o presente trabalho, objetivou-se estimar a capacidade combinatória de linhagens de tomate ricas em acilaçúcares (AA) quando cruzadas com linhagens com baixo teor de acilaçúcares e estudar a expressão da heterose nos híbridos obtidos. O experimento foi realizado no campo da HortiAgro Sementes Ltda, localizada em Ijaci-MG. O material genético foi constituído de seis híbridos experimentais em esquema de dialelo parcial, constituído de três genitores masculinos (grupo I, com altos teores de acilaçúcares) e dois genitores femininos (grupo II, com baixos teores). Foram avaliadas as características: massa média de fruto (g fruto-1) e produção por hectare (t ha-1). As linhagens TOM-687 e TOM-688 (ricas em AA e resistentes a pragas) apresentaram estimativas positivas dos efeitos de capacidade geral de combinação, para massa média de frutos, e estimativas negativas, para produção, o que significa que elas contribuíram positivamente para aumento no tamanho do fruto, mas reduziram a produtividade dos híbridos. Já a linhagem TOM-689, ao contrário das duas anteriores, contribuiu para reduzir o tamanho do fruto, mas contribuiu para aumentar a produtividade dos híbridos. Os híbridos obtidos do cruzamento de linhagens com altos teores de acilaçúcares mostraram-se competitivas quando comparadas a híbridos comerciais encontrados no mercado. As melhores combinações híbridos foram obtidas quando as linhas com altos teores de acilaçúcares foram cruzadas com a linhagem elite TOM-684.
The objective of this work was to assess heterosis and combining ability of tomato lines with high acylsugar (AS) content (group I) and lines with low AS (group II) used to produce AS-rich tomato hybrids. The trial was carried out at the seed production station of the HortiAgro Sementes Ltda., at Ijaci-MG. The genetic material consisted of six experimental hybrids obtained from crosses between three male parents with high AS (group I) and two female parents with low AS (group II). Average fruit weight (g fruit-1) and total yield (t ha-1) were the traits assessed. The AS-rich pest-resistant lines TOM-687 and TOM-688 showed positive estimates of general combining ability for average fruit mass and negative for yield, increasing fruit size, and reducing the yield of the hybrids. Unlike the two previous lines, TOM-689 presented negative estimates for fruit mass and positive for fruit yield. The data showed that it is feasible to get competitive hybrids from lines with AS sugar content. The best hybrids were produced when these lines were crossed with TOM-684.