Inheritance of yield and quality characteristics in processing tomatoes

[摘要] English: The main objective of this study was to determine the combining ability ofseveral tomato genotypes, the heritability of various yield and qualitycharacteristics and the expression of heterosis in the F1 hybrids.2. Six inbred tomato genotypes were used as parental lines in the diallelcross. Crosses were made in glasshouses at the University of the OrangeFree State. The F1 hybrids and their parental lines were planted at the ARC- Roodeplaat Vegetable and Ornamental Plant Institute. Various yield andquality characteristics were analysed.3. Significant differences among the six parental lines were recorded for totalyield, marketable yield, green yield and average fruit mass. The 15 F1hybrids showed significant differences for total yield, marketable yield,unmarketable yield, green yield and average fruit mass.4. Significant genetic variation among the SIX parental genotypes wasrecorded for fruit pH. The 15 F1 hybrids show no significant differencesfor soluble solid content and fruit pH.5. A significant positive phenotypic correlation (r=0.95) was found betweentotal yield and marketable yield.6. Inbred line p88/120 was the best general combiner for most of the yieldcharacteristics while p88/120 and p88/192 is the best general combinersfor most of the quality characteristics.Crosses p881l40 x UC82B, P881l20 x p88/192 and p881l40 x p881l92were the best specific combiners for total and marketable yield. The bestspecific combination was the cross between p88/164 and UC82B, whichhad 7 positive SCA values.8. A GCA:SCA ratio of 85:1 was recorded for average fruit mass indicatingthat additive genes are involved.9. Narrow sense heritability were relatively high for average fruit mass (H2n=74.38%), green yield (H2n=55.01 %) and fruit colour (H2n= 50.04%). Thebreeder can select effectively for larger fruited genotypes as well asselecting against green yield to increase the total yield.10. The average level of heterosis over the best parent exceeds 10% for totaland marketable yield between all the F1 hybrids. Heterosis of the F1hybrids over mid-parent value (Hmp), heterosis over the better parent(Hbp) and superiority over the best parent (Scm) was mostly negative forall the quality characteristics.

[发布机构] University of the Free State