Diallel cross among fresh market tomato inbreeding lines

Abstract

The general combining ability (GCA), specific combining ability (SCA), and heterosis were studied in a complete diallel cross among fresh market tomato breeding lines with reciprocal excluded. Fifteen genotypes (five parents and ten hybrids) were tested using a randomized complete block design, with three replications, and the experiments were conducted in Itatiba, São Paulo state, Brazil, in 2005/06. The yield components evaluated were fruit yield per plant (FP), fruit number per plant (FN), average fruit weight (FW); cluster number per plant (CN); fruit number per cluster (FC), fruit wall thickness (FT) and number of locules per fruit (NL). Fruit quality components evaluated were total soluble solids (SS); total titratable acidity (TA); SS/TA ratio, fruit length (FL); fruit width (WI); length to width ratio (FL/WI). The data for each trait was first subjected to analysis of variance. Griffing's method 2, model 1 was employed to estimate the general (GCA) and specific (SCA) combining abilities. Parental and hybrid data for each trait were used to estimate of midparent heterosis. For plant fruit yield, IAC-2 was the best parental line with the highest GCA followed by IAC-4 and IAC-1 lines. The hybrids IAC-1 x IAC-2, IAC-1 x IAC-4 and IAC-2 x IAC-4 showed the highest effects of SCA. High heterotic responses were found for fruit yield and plant fruit number with values up to 49.72% and 47.19%, respectively. The best hybrids for fruit yield and plant fruit number were IAC-1 x IAC-2, IAC-1 x IAC-4 and IAC-2 x IAC-5, for fruit yield and plant fruit number, the main yield components.

Combining ability and heterosis of relevant fruit traits of tomato genotypes for industrial processing

“…This indicates the existence of genetic variability between the parent lines, experimental hybrids and commercial hybrids for all evaluated properties, making the selection of the best genotypes possible. The recombination of pre-existing genetic variability by means of diallel crosses resulted in the formation of different experimental hybrids for the evaluated traits, allowing selection and finally recommendation of the best hybrids in the breeding program aimed at improving fruit quality properties (Melo et al 2009, Santos et al 2011, Souza et al 2012). …”

“…Thus, no intrapopulational breeding strategies have been used in current tomato breeding programs, due to the low resulting genetic gain (Amaral Júnior et al 1999, Souza et al 2012.…”

Análise dialélica da produtividade e do progresso da severidade de doenças foliares em híbridos de milho em duas densidades populacionais

“…A análise desses efeitos indica a direção dos desvios de dominância, de modo que se a estimativa for negativa os desvios de dominância serão predominantemente positivos e vice-versa (SOUZA et al, 2012). Embora o genitor GNZ2004 tenha apresentado estimativa negativa de ŝ ii para a produtividade de grãos (Tabela 3), a magnitude do valor de ŝ ii foi pequena, indicando que a sua frequência gênica está mais próxima da frequência média da população e, consequentemente, menos divergente ele é em relação aos demais genitores.…”

Assessment of 112 tomato (Solanum lycopersicum L.) cultivars for industrial processing in Portoviejo, Ecuador

“…Tomato is a self-pollinating species and its genetic base becomes narrower along the domestication processes. Therefore, the strategy to prevent intra-population reproduction leads to genetic gain in crop improvement (Souza, Paterniani, de Melo & de Melo, 2012). In this regard, genetic variability recombination is an excellent alternative to obtain plants with superior characteristics (Maciel, Maluf, Silva, Gonçalves, Nogueira & Gomes, 2011).…”