Full text in pdf format

Genetic analysis of components of fruit size and shape in a diallel cross of tomato cultivars

W.R. Maluc^I; J.E.C. Miranda^II; P.E. Ferreira-Rossi^III

^IBioplanta Tecnologia de Plantas S.A., Caixa Postal 1141, 13100 Campinas, SP, Brasil. Send correspondence to W.R.M.
^IICentro Nacional de Pesquisa de Hortaliças (CNPH)/EMBRAPA, 70359 Brasília, DF, Brasil
^IIICATIE, Turrialba, Costa Rica

ABSTRACT

Traits related to fruit size and shape (average fruit weight = FW, number of locules per fruit = LF, average weight per locule = WL; fruit length/diameter ratio = FR) were studied in a partial complete diallel cross of six tomato (Lycopersicon esculentum Mill.) cultivars: 1. Euromech; 2. Flora-Dade; 3. Rio Grande; 4. Royal Chico; 5. UC-82; 6. VF-65 -433. In cultivars 1, 3 and 5, fruit are barrel-shaped (FR values around 1.10-1.20); in cultivar 2, deep-oblate (FR = 0.88); in cultivar 4, pear-shaped (FR = 1.41); and in cultivar 6, cylindrical (FR = 1.99). Diallel analysis of Gardner and Eberhart (Biometrics 22: 439-452, 1966) demonstrated that the variety effects were more important than heterosis effects for the four traits under consideration. The predominantly additive nature of the genetic effects was the cause of high correlations found between hybrid and parental means in all cases. Jinks and Hayman's approach to diallel analysis indicates that partial dominance is involved in the expression of WL and FR. Partially dominant alleles act in the direc- tion of smaller WL and FR. Genotypic correlations among the traits were generally low (except between FW and LF), indicating that genetic progress could be obtained for both larger FW and higher FR. The results indicate that F₁ hybrids with barrel-shaped fruit can be obtained from parents such as Flora-Dade only if the other parent has an FR value around 2.0.

Keywords: Diallel cross; Tomato.

REFERENCES

Cheng, S.S. (1972). Avaliação de algumas características agronômicas em híbridos de tomateiro (Lycopersicon esculentum Mill.). Masters Thesis, UFV, Viçosa.

Dias, M.S. (1960). Produção de sementes híbridas F₁ no tomateiro. Viçosa; UREMG. 3p. (Hortaliças: Cultura do tomateiro).

Fogle, H.W. and Currence, T.M. (1950). Inheritance of fruit weight and earliness in a tomato cross. Genetics 35: 363-380.

Gardner, C.O. and Eberhart, SA. (1966). Analysis and interpretation of the variety cross diallel and related populations. Biometrics 22: 439-452.

Gontijo, M.C., Maluf, W.R. and Miranda, J.E.C. (1983). Análise genética do peso médio por lóculo em um cruzamento dialélico de cultivares de tomate (Lycopersicon esculentum Mill.). Hort. Bras. 1:24-27.

Hallauer, A.R. and Miranda Filho, J.B. (1981). Quantitative Genetics in Maize Breeding. Iowa State University Press, Ames. 468 p.

Hayman, B.I. (1954a). The analysis of variance of diallel tables. Biometrics 10: 235-244.

Hayman, B.I. (1954b). The theory and analysis of diallel crosses. Genetics 39: 789-809.

Larson, R.E. and Currence, T.M. (1944). The extent of hybrid vigor in F₁ and F₂ generations of tomato crosses. Minn. Agr. Exp. Sta. Techn. Bull. 164:1-32.

Maluf, W.R., Miranda, J.E.C. and Campos, J.P. (1982). Análise genética de um cruzamento dialélico de cultivares de tomate. I. Características referentes à produção de frutos. Pesq. Agropec. Bras. 17: 633-641.

Maluf, W.R., Ferreira, P.E. and Miranda, J.E.C. (1983). Genetic divergence in tomatoes and its relationship with heterosis for yield in F₁ hybrids. Rev. Brasil. Genet. 6: 453-4670.

Mello, P.C.T., Miranda, J.E.C. and Costa, C.P. (1988). Possibilidades e limitações do uso de híbridos F₁ de tomate. Hort. Bras. 6: 4-6.

Melo, P.C.T. (1988). Heterose e capacidade combinatória em um cruzamento dialélico parcial de cultivares de tomate (Lycopersicon esculentum Mill.). Doctoral Thesis, ESALQ/USP, Piracicaba.

Miranda, J.E.C. (1978). Avaliação de seis cultivares de tomate (Lycopersicon esculentum Mill.) e suas progênies híbridas F₁. Masters Thesis, UFV, Viçosa, MG.

Miranda, J.E.C., Maluf, W.R. and Campos, J.P. (1982). Análise genética de um cruzamento dialélico de cultivares de tomate. II. Características vegetativas. Pesq. Agropec. Bras. 17:767-773.

Miranda Filho, J.B. and Vencovsky, R. (1978). Coeficiente de correlação entre as médias de variedades e dos híbridos intervarietais em cruzamentos dialélicos. Relat. Ci. Inst. Genet. Esc. Sup. Agric. Luiz de Queiroz 12: 147-161.

Powers, L. (1945). Relative yields of inbred lines and F₁ hybrids of tomato. Botan. Gaz. 106: 247-268.

Powers, L. (1950). Gene analysis of weight per locule in tomato hybrids. Botan. Gaz. 112: 163-174.

Powers, L. (1952). Gene recombination and heterosis. In: Heterosis. (Gowen, J.W., ed). Ames, Iowa State University Press. Chapter 19.

Rick, C.M. and Butler, L. (1956). Cytogenetics of the tomato. Adv. Genet. 8: 267-382.

Statistical Analysis System Institute Inc. (1979). SAS User's Guide. Raleigh, North Carolina, 494 p.