Genetic Analysis of Quantitative and Fruit Cracking Characters in Tomato (Lycopersicon esculentum Mill.).

Abstract

Tomato fruit cracking had became one of the problems in lowland cultivation. Morphology characterization of twenty five tomato genotypes were carried out to evaluate the fruit cracking tolerance level and the genetic diversity. Ten genotypes were selected to estimate variance and heritabilities of crack index character, yield and component of yield, fruit and vegetative character and then six genotypes were selected to conduct a 6×6 full diallel cross set of tomato to estimate genetic parameter, combining ability and hybrid performance. The experiment was conducted from April until August 2012 and from April until August 2013 at Leuwikopo Field Station (6o56‟34‟‟S, 106o72‟56‟‟E), Bogor Agricultural University. Randomized complete block design was used with three replications. The genetic diversity was analyzed by clustering analysis. Marker character were selected based on heritabilities value and correlation between character. Genetic parameter was analized by Hayman method and combining ability was analyzed by Griffing Method. The difference between the hybrids and varieties comercial was analyzed by Dunnet‟s tested. Result of resistance evaluation showed that fruit crack index of 25 tomato genotypes range from 0.00 to 20.58. According to quantitative character some genotype can be selected as material breeding. Based on genetic diversity analysis, all genotypes could be divided into four groups. Tomato genotypes IPBT1, IPBT3, IPBT13, IPT33, IPBT60, IPBT64, IPBT73, IPBT 78, IPBT83 dan IPBT86 were recommended as parent of diallel cross to fruit cracking genetic analysis. The marker selection on tomato breeding program to develop tomato varieties that have high yield and fruit cracking resistant using characters with high heritabilities value, correlated significantly and directly influent to the fruit crack index. Fruit cracking character, yield and components of yield, fruit character and vegetative character include to the high category of heritability. According correlation and path analysis the three components very highly correlated with crack index were fruit crack weight percentage of plant, number of fruit crack percentage of plant and total soluble solids. The three components that very highly correlated with yield per plant were marketable fruit weight, individual fruit weight and plant height. Fruit cracking character is controlled by additive and dominant gene effect, but dominant effect more significant than additive effect. Based on genetic parameter and combining ability, the control of additive as well as v non-additive gene effects for all of the character were highly significant. The highest significant reciprocal effect occurs for yield per plant, number of fruit, individual fruit weight, fruit length, fruit diameter, number of locule and fruit thickness. The analysis of variance for general combining ability (GCA) and specific combining ability (SCA) were significant for all traits. Pure line varieties breeding programs could be developed if variance for GCA were highly significant and the genotype parent has a good estimated GCA value. Tomato genotype IPBT78 proved to be the best general combiner for yield and yield components. Hybrid varieties breeding programs developed if variance for SCA were highly significant and the genotype parent has a good estimated SCA value. The most recommended cross combinations are IPBT3×IPBT78, IPBT78×IPBT3, IPBT13×IPBT78 and IPBT64×IPBT78. Hybrids performance show that some character are better than commercial variety or have similar performance to the commercial variety. Therefore, it is highly suggested for further test to obtain information of adaptation and preference of consumers. Tomato genotype IPBT78 proved to be the best general combiner for yield and yield components. The most recommended cross combinations are IPBT3× IPBT78, IPBT78×IPBT3, IPBT13×IPBT78 and IPBT64×IPBT78.