Analysis Of Heterosis And Combining Ability Of Tomato Inbred Line

Tomato(Solanum lycopersicum)originated in South America and is widely enjoyed around the world.It is one of the most common vegetables in the world and is widely grown worldwide.It is a comprehensive evaluation of tomato germplasm resources to screen out good new varieties of tomato.The main breeding objectives of tomato include the following aspects: First,to improve productivity;Second,enhance resistance to biotic and abiotic stresses;Third,improve fruit appearance and nutritional quality.Nowadays,the traditional breeding methods can not meet the needs of modern breeding.In order to better achieve the goal of modern tomato breeding,we carried out the breeding and application of hybrid varieties.The breeding and application of hybrid varieties has become one of the hot spots in modern tomato breeding research.In this experiment,according to the design of Griffing IV incomplete diallel cross,55 cross combinations were screened out by using 11 good parents of related agronomic traits.Heterosis and combining ability of tomato yield,early maturity and quality traits were studied and analyzed by random block repetition method for three times in all F1 generation crosses and their parents,in order to screen out the combinations with strong superiority and high combining ability.The main findings are as follows:(1)The 11 parents of 8 agronomic traits were divided into 3 groups by agronomic character cluster analysis,of which 18954,18753,18P24,18696 and 18P100 were divided into the first group,18786,18920,18734 and 18943 were the second group,and 18764 and 18P107 were the third group.The results showed that the tomato materials of the three groups had obvious genetic differences.Therefore,in the breeding process,it is indicated that parents of different groups can be selected first for hybridization,which can save most of the time and resources and further reduce the range of parental selection.(2)A number of parents with high GCA were selected.The parents with the highest GCA value of plant height were 18p24,18753 and 18p100.The parents with the largest GCA effect value were18p100,18p24 and 18786.The parents with the highest GCA value of single fruit weight were18734,18920,18943.The parents with the highest GCA value of early yield were 18p107,18p100 and 18734.The parents with the highest GCA effect value at maturity stage were 189431892018954.The parents with the highest GCA value of hardness were 18753,18696 and 18p24.The parent with the highest GCA effect value of fruit shape index was 18p24,18920 and 18943.The parent with the highest GCA effect value of pulp thickness was 18786,18943 and 18954.(3)A group of combination with high special combining ability combination were selected as:in plant height,the three hybrid combinations with higher value of special combining ability for plant height were 18920 × 18P24(125.27)、18954 × 18753(122.60)and 18P100 × 18p24(121.33),these three combinations showed higher plant height.In the number of fruit,the most effective hybrid combination 18786 × 18p100(18.61);In the single fruit weight,the hybrid combination with the highest SCA effect value was 18920 × 18734(358.70).The hybrid combination 18p100×18p107(12.31)had the largest effect on the special combining ability of early yield.In the mature stage,the hybrid combination with the largest effect value of SCA was 18954x18764(123.33).The combination with the largest effect value of special combining ability of hardness is 18p24 × 18696(70.23).In fruit shape index,the combination with the highest SCA effect value was 18920 ×18p24(0.88),and the maximum combining ability effect value of hybrid combination in pulp thickness was 18954×18943(1.05),it should be used as an excellent hybrid.(4)Screening out a batch of strong and advantageous combinations.The strong dominant combinations in yield traits were: 18920×18P24,18786×18P100,18920×18734 and 18P24 ×18734;It has the advantages of high total yield and large fruit.The 18P100×18P107 and 18954×18764 precocious combinations showed early maturity and high early yield.The combinations with the best quality traits were 18920×18P24,18P24×18696 and 18954×18943,which showed the advantages of high hardness and high sugar content.In addition,the parent 18P24,as the female parent,showed good performance in all traits.(5)The heritability of each tomato trait was in the order of plant height >number > per fruit weight >early yield >flesh thickness >hardness >fruit shape index >maturity stage.The ratio of narrow heritability to broad heritability of traits such as plant height,fruit weight and number of fruit per plant was high,indicating that the genetic effect was mainly additive.However,the narrow heritability and the broad heritability of the mature traits were lower and the dominant effect was higher.