Diallel cross among fresh market tomato inbreeding lines

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, s？o 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 mid-parent 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.