1. THE INHERITANCE OF PLANT HEIGHT IN HEXAPLOID WHEAT (Triticum aestivum L.) Nataša LJUBIČIĆ 1*, Sofija PETROVIĆ 1, Miodrag DIMITRIJEVIĆ 1, Nikola HRISTOV 2 1 University of Novi Sad, Faculty of Agriculture, Novi Sad, Serbia 2 Institute of Field and Vegetable Crops, Novi Sad, Serbia *Corresponding author: ljubicic.natasa@gmail.com ABSTRACT Five winter wheat varieties (Pobeda, Renesansa, Sara, Partizanka and Pesma) have been selected for diallel crossing in order to estimate the mode of inheritance, gene effect and genetic variance components for the plant height in F1 generation. The mode of inheritance was done on the basis of the significance of components of genetic variance and the regression analysis. The combining ability analysis indicated significant differences for the general (GCA) and specific (SCA) combining ability in the F1 generation, which means that plant height had resulted from the genes with additive and non-additive impact. The best GCA was denoted in varieties Partizanka and Pesma and the best SCA have shown in cross combination Partizanka/Pesma. The genetic components of variance, average degree of dominance and regression line indicated over-dominance in the inheritance of plant height. Keywords: wheat, plant height, diallel, regression. INTRODUCTION An efficient wheat improvement program requires an understanding of genetic mechanism involved in the expression of yield and yield components of plant material to be used in hybridization program. Plant breeders frequently use diallel analysis for testing a number of parental lines in all possible combinations. Diallel analysis is a suitable method for estimating of genetic parameters and provides early information on the genetic behaviour of these traits in the first generation. Techniques for analyzing genotypes for all possible crosses include diallel analysis of variance, calculation of genetic components of variation, Vr/Wr regression analysis, as well as estimation general and specific combining ability effects. Since that inheritance of plant height, as one of several yield components of wheat, has complex nature, the aim of this study was to obtain the information about inheritance of plant height in a 5×5 diallel cross of wheat. These results would be additional information in the selection of desirable parents for an effective breeding program to evolve new varieties of economic importance. MATERIALS AND METHODS Five winter wheat genotypes, (Triticum aestivum L.), Pobeda, Renesansa, Sara, Partizanka and Pesma, were crossed in all possible combinations following an 5×5 diallel mating system and it was obtained F1 generation of progenies. The experiment was conducted at the trial field of the Institute of Field and Vegetable Crops in Novi Sad, according to random block design with three replications, in three growing seasons (2009/2010, 2010/2011 and 2011/2012). At the stage of full maturity, ten plants from each replication of hybrids and parents were selected randomly for recording data for plant height. Average values of three years trait analysis were used. Analysis of variance for parents and F1 hybrids for the plant height was done according to Steel and Torrie (1980). General combining ability (GCA) and specific combining ability (SCA) was done following the Method 2 (parents and F 1 generation) Mathematical Model 1 of Griffing (1956). The regression analysis was conducted by the method of Mather and Jinks (1971). The components of genetic variance were analyzed following the models of Hayman (1954) and Jinks (1954). RESULTS Table 1. Analysis of variance for parents and F 1 hybrids for the plant height in a 5×5 diallel cross of bread wheat Source of variance F t DFSSMSF0.050.01 Replications23743.091871.54220.19**3.325.39 Genotypes14 332.0623.72 2.79*2.602.84 Error28 237.998.50 Total444313.13 + DF: Degree of Freedom, SS: Sum of Squares, MS: Mean Square, F: Level of Significance by the F test; Significant (P< 0.05), Highly significant (P < 0.01), Non-significant (ns) Table 2. Analysis of variance for combining ability for the plant height in a 5×5 diallel cross of bread wheat Source of variance F t DFSSMSF0.050.01 GCA431.807.952.81**2.694.02 SCA10 78.887.892.78*2.162.98 E28 237.992.83 GCA/SCA1.01 + GCA: General Combining Ability, SCA: Specific Combining Ability, E: Error; DF: Degree of Freedom, SS: Sum of Squares, MS: Mean Square, F: Level of Significance by the F test; Significant (P < 0.05), Highly significant (P < 0.01), Non-significant (ns) Table 3. Estimates of GCA effects for the plant height in 5×5 diallel cross of wheat Parents GCA values Rank SE LSD 0.05 0.01 Pobeda -0.826 ns 4 Renesansa -1.216 ns 5 0.9001.822.43 Sara -0.127 ns 3 Partizanka 1.084 ns 1 Pesma 1.083 ns 2 + GCA: General Combining Ability, SE: Standard Error; LSD: Least Significant Difference test; Significant (P < 0.05), Highly significant (P < 0.01), Non-significant (ns) Table 5. Genetic components of variation for the plant height of wheat ComponentValues D1.48 H1H1 25.88 H2H2 20.72 F1.17 E2.83 H 2 /4H 1 0.20 u=p0.72 v=q0.28 √(H 1 /D)4.19 K D /K R 1.21 + D: Additive effect, H 1 and H 2 : Dominance effect, F: Frequencies of dominant to recessive alleles in parents, E: Environment effect, H 2 /4H 1 : Proportion of genes with positive and negative effects in the parents, u: The values of dominant alleles, v: The value of recessive alleles, √(H 1 /D): The average degree of dominance, (K D /K R ): Ratio of the total number of dominant against recessive alleles Table 4. Estimates of SCA effects for the plant height in a 5×5 diallel cross of bread wheat Parents LSD PobedaRenesansaSaraPartizankaPesma SE0.050.01 Pobeda 0.462 ns 1.810 ns -0.305 ns 1.357 ns Renesansa 2.033 ns -2.714 ns -3.752 ns 2.01 4.065.43 Sara -0.867 ns 2.262 ns Partizanka 4.781* + SCA: Specific Combining Ability, SE: Standard Error; LSD: Least Significant Difference test; Significant (P < 0.05), Highly significant (P < 0.01), Non-significant (ns) CONCLUSION The results revealed that there was significant genetic variation for the plant height of wheat among the genotypes and among the years. Significant GCA and SCA effects imply the role of both additive and non-additive gene actions in the genetic control of the trait. The largest value of positive GCA effects were observed in genotypes Partizanka and Pesma, suggesting that these genotypes contain more genes with additive effects or additive×additive interaction effects and could be a good parent for this trait. The highest positive significant SCA effect exhibited by the cross Partizanka/Pesma (high x high general combiner) indicated the possibility of genetic improvement for this trait through pedigree selection. The regression analysis in F 1 generations indicated over-dominant inheritance of the plant height, which was confirmed using the analysis of the components of the genetic variance. Regression coefficient was significantly different from unity, suggesting the presence of non-allelic interaction and indicated that variation for plant height of wheat is under polygenic control. CONCLUSION The results revealed that there was significant genetic variation for the plant height of wheat among the genotypes and among the years. Significant GCA and SCA effects imply the role of both additive and non-additive gene actions in the genetic control of the trait. The largest value of positive GCA effects were observed in genotypes Partizanka and Pesma, suggesting that these genotypes contain more genes with additive effects or additive×additive interaction effects and could be a good parent for this trait. The highest positive significant SCA effect exhibited by the cross Partizanka/Pesma (high x high general combiner) indicated the possibility of genetic improvement for this trait through pedigree selection. The regression analysis in F 1 generations indicated over-dominant inheritance of the plant height, which was confirmed using the analysis of the components of the genetic variance. Regression coefficient was significantly different from unity, suggesting the presence of non-allelic interaction and indicated that variation for plant height of wheat is under polygenic control. Figure 1.Vr/Wr regression analysis for the plant height of bread wheat Acknowledgement This investigation was supported by the Ministry of Education, Science and Technology Development of Republic of Serbia, Project no. TR 31066.