A seleção de famílias não tem sido um método recomendado para a seleção de plantas de propagação vegetativa. Para verificar sua utilidade no melhoramento da batata, realizou-se uma série de experimentos em condições de temperaturas elevadas (safra das águas). Trinta famílias clonais provenientes de genitores tolerantes ao calor foram avaliadas para produção e peso específico de tubérculos. Depois de obtidas a geração seedling (GS) e a primeira geração clonal (PGC) foram avaliados clones individuais, por mais duas gerações. Foram realizadas simulações de diferentes intensidades de seleção de famílias na GS e PGC e intensidades de seleção de clones nas gerações seguintes. Os resultados indicam que intensidades de 50 e 60% produzem os maiores ganhos. As estimativas da h² em nível de famílias foram maiores que em nível de clones, o que confirma a eficiência da seleção de famílias em gerações precoces. A seleção de famílias para peso específico pode ser realizada em gerações precoces (GS e PGC), independentemente das condições de temperatura que será realizada a seleção clonal. A seleção sequencial de famílias, com intensidades de 60% (SG) e 60% (PGC), promoveria maior eficiência da seleção de clones na segunda e terceira geração clonal. No caso de aplicar intensidades mais fortes para aumentar a eficiência da seleção sequencial (GS e PGC), intensidades fracas devem ser aplicadas na GS e mais fortes na PGC . A seleção de famílias para a produtividade de tubérculos poderia ser aplicada na PGC, desde que a seleção de clones individuais não ocorra em condições contrastantes de temperatura.

Families selection has not been recommended as a selection method for vegetative propagated species. To verify its utility for potato improvement a series of experiments were carried out under warm temperatures (rainy season). Thirty clonal families originated from heat tolerant parents were evaluated for tuber yield and specific gravity. After obtaining the seedling generation (SG) and the first clonal generation (FCG) individual clones from a further two generations were assessed. Simulations were conducted with different intensities of family selection in SG and FCG and intensities of clonal selection in subsequent generations. The results show that family selection intensities between 50% and 60% allowed the greatest gains. Estimates of h² at the families level were always higher than at the clones level and corroborate for the more effective selection of families in early generations. The selection of families for tuber specific gravity can be made in the early generations (SG and FCG) regardless of the temperature conditions where the individual clones will be selected. The sequential selection of families with intensities of 60% (SG) and 60% (FCG) would promote greater efficiency for the selection of clones in second or third clonal generation. In the case of applying stronger selection intensities for a higher efficiency with sequential selection (SG and FCG) weaker intensities should be applied in the SG and stronger intensity in FCG . Family selection for tuber yield could be practiced in the FCG as long as the selection of clones was not held in contrasting temperature conditions.

Geralmente a seleção de clones de batata para produtividade é eficiente a partir da segunda geração clonal. No entanto, seria ideal selecionar a partir da geração seedling (GS) ou na primeira geração clonal (PGC). O objetivo deste trabalho foi avaliar, em nível de famílias, a repetibilidade da seleção em gerações mais precoces sobre as mais tardias, nas épocas quentes, para produtividade e peso específico. Foram avaliadas 30 famílias na GS, PGC, segunda, terceira e quarta geração clonal, sem realizar seleção nenhuma. Logo, foram obtidas as médias ajustadas das 30 famílias para cada geração. Foram simuladas seleções de famílias nas diferentes gerações de forma independente; e depois verificada a repetibilidade dessas famílias entre as gerações utilizando igual intensidade de seleção. Os resultados mostraram que a seleção de famílias na GS e PGC para peso específico e na PGC para produtividade é eficiente, tanto em condições de temperaturas amenas como em calor.

The selection of potato clones for yield is usually effective from the second clonal generation. It would however be ideal to select from the seedling generation (SG) or the first clonal generation (FCG). The aim of this study was to evaluate the repeatability of selection at the family level performed in the early generations with the subsequent generations, for tuber yield and specific gravity in the warm season. Thirty families were evaluated in the SG, FCG and the second, third and fourth clonal generation, without any selection. In this way, adjusted means of the 30 families were obtained for each generation. Selections were simulated independently in the different family generations, and then the repeatability of these families among generations verified, using the same selection intensity. The results showed that the family selection in the SG and FCG for specific gravity and in the FCG for tuber yield is efficient, at mild as well as warm temperatures.

The aim was to assess heterosis in a set of 16 summer-squash hybrids, and evaluate the combining capacity of the respective parental lines, which differed as to the degree of parthenocarpy and resistance to PRSV-W (Papaya Ringspot Virus-Watermelon strain). The hybrids were obtained using a partial diallel cross design (4 x 4). The lines of parental group I were 1 = ABX-037G-77-03-05-01-01-bulk, 2 = ABX-037G-77-03-05-03-10-bulk, 3 = ABX-037G77-03-05-01-04-bulk and 4 = ABX-037G-77-03-05-05-01-bulk, and of group II, 1' = ABX-037G-77-03-05-04-08-bulk, 2' = ABX-037G-77-03-05-02-11-bulk, 3' = Clarice and 4' = Caserta. The 16 hybrids and eight parental lines were evaluated for PRSV-W resistance, parthenocarpic expression and yield in randomized complete-block designs, with three replications. Parthenocarpy and the resistance to PRSV-W were rated by means of a scale from 1 to 5, where 1 = non-parthenocarpic or high resistance to PRSV-W, and 5 = parthenocarpic or high susceptibility to PRSV-W. Both additive and non-additive gene effects were important in the expression of parthenocarpy and resistance to PRSV-W. Whereas estimates of heterosis in parthenocarpy usually tended towards a higher degree, resistance to PRSV-W was towards higher susceptibility. At least one F1 hybrid was identified with a satisfactory degree of parthenocarpy, resistance to PRSV-W and high fruit-yield.