Estimation of heritability and genetic advance in F 3 populations of wheat

Knowledge of inheritance of important plant traits is the basis of selection program. To check genetic variability and transmission pattern of essential plant characters, a research was conducted comprising 8 parents and 8 cross combinations at the research fields of The University of Agriculture, Peshawar, during 2014-15. The experiment was laid out using randomized complete block design with three repetitions. Data were recorded on yield and other important plant traits. Sufficient variations were detected for all the studied traits showing adequate scope of crop improvement. Traits like flag leaf area (0.82), plant height (0.81), fertile tillers plant (0.83), biological yield (0.90), grains spike (0.93) and grain yield plant (0.90) manifested high heritability estimates with high genetic advance (14.15, 13.48, 4.57, 28.28, 21.64 and 15.7, respectively) suggested that they were under additive gene control. We recommend Tatara × Janbaz, AUP-5008 × Janbaz, Saleem-2000 × Siren, Saleem-2000 × Janbaz and AUP-5008 × Siren to be further assessed in cultivar development programs.


Introduction
Wheat is not only the world's main cereal crop but also a staple food item in many parts of the world.It is the member of family Poaceae also known as Graminae.Wheat is believed to be the first cereal which has ever been domesticated by human beings.Unlike wheat counterparts, its ability of self-pollination and simplicity has made it more attractive to many breeders who have developed many varieties merely by selection.The success of any breeding program could only be realized by effective selection.The wider the scale of heritable differences the effective will be the selection.Therefore, information regarding heredity of important plant traits is crucial to proceed in the right direction [1].The values of heritability can serve in measuring the degree of association between parents and their offspring [2].High heritability estimates associated with high genetic advance can increase the chances of success from selection in cultivar development.High yield is one of the prime objectives in any breeding program.Since yield is a quantitative and complex trait, therefore the knowledge of genetic expression of all its associated components is prerequisite for higher yield.Extensive research work is being going on to concentrate the desirable genes in the existing germplasm to achieve the goal of high productivity.Unfortunately, fixable (additive) genes are lesser in proportion than non-fixable (non-additive or epistatic) genes therefore, to utilize both, breeding methods like bi-parental crossing is usually suggested to improve the grain yield and other related traits [3].Present research work was therefore designed to assess the gene flow and heritability in specific wheat crosses.This information will help in planning effective breeding strategy to select hybrids or potential segregants with desired traits in succeeding generations.

Materials and methods
Present research was carried out in the research fields of The University of Agriculture, Peshawar, Pakistan during 2014-15.The plant material consisted eight parents and their eight F3 progenies (Table 1).Seeds of parental lines along with their selected F3 crosses were space planted in randomized complete block design with three replicates.Each plot consists of three rows per entry of 3 m row length, row to row and plant to plant spacing was kept at 30 cm and 15 cm, respectively.Standard cultural practices were carried throughout the growing season.Productive tillers plant -1 is an important yield component as it is directly correlated with number of spikes plant -1 .Thus, increase in tillers plant -1 could ensure greater yield.Mean data of genotypes regarding fertile tillers plant -1 ranged between 7 and 10 (for Janbaz and AUP-5008, respectively).Whereas, among segregating population, maximum number of tillers were recorded for Aup-5008 × Janbaz and Barsat × Siren, while minimum number of tillers were displayed by Tatara × Janbaz (Table 3).Among parental genotypes, variances varied from 1.30 to 2.65.Minimum variation was observed for Barsat (1.30), whereas maximum variation was recorded for parent Janbaz (2.65).Among F3 populations minimum variation (4.32) was observed for AUP-5008 × Janbaz, whereas, maximum variation was recorded (9.72) for genotype Saleem-2000 × Janbaz ( g (Barsat × Siren) to 3.51 (Saleem-2000 × Siren).Variation among genotypes ranged from 0.10 to 0.23 for 100-grain weight.Minimum variation (0.10) was observed in parental genotype Pirsabak-2005, while the maximum variation (0.23) was recorded for genotype Saleem-2000.In F3 populations minimum variation (0.21) was observed in genotype Barsat × Siren, whereas, maximum variation (0.59) was recorded for genotype Saleem-2000 × Janbaz (Table 4).Heritability magnitude and genetic advance varied from 0.33 to 0.71 and 0.30 to 0.96, respectively.Maximum heritability (0.71) accompanied with low genetic advance (0.96) was calculated for genotype Saleem-2000 × Janbaz suggesting the predominance of non-additive gene action, whereas, minimum heritability (0.33) and genetic advance (0.30) was observed for cross of AUP-5008 × Janbaz (Table 4) implying role of environment in the inheritance of this trait.Jan et al. [13] also observed high heritability coupled with low genetic advance among their wheat genotypes.

Biological yield plant -1
Biological yield plant -1 ranged from 42.7 g to 64.3 g.Maximum biological yield (59.1 g) among parental genotypes were recorded for AUP-5008, whereas, genotype Janbaz showed minimum value (42.7 g) for biological yield.Among F3 populations AUP-5008 × Janbaz showed maximum biological yield (64.3 g), whereas, Barsat × Janbaz displayed minimum biological yield (44.2).Among parents, minimum variation (20.43) was observed for Janbaz, while maximum variation (45.61) was observed for Saleem-2000.Among F3 populations minimum variation was observed (179.32) for Tatara × Janbaz, whereas maximum (320.32) for cross Tatara × Siren (Table 4).In F3 population broad sense heritability and genetic advance for biological yield ranged from 0.70 to 0.90 and 20.03 to 28.28, respectively.Maximum heritability (0.90) and genetic advance (28.28) for was recorded for Saleem-2000 × Janbaz, whereas, minimum heritability (0.70) and genetic advance (20.17) was observed for cross combination AUP-5008 × Janbaz (Table 4).All crosses showed high heritability estimates with suitable genetic advance indicating adequate possibility of improvement could be expected from selection.Our results are in line with those obtained by Kumar et al. [14], who observed high broad sense heritability coupled with high genetic advance for biological yield among wheat genotypes, whereas, contradictory results have been reported by Khalid et al. [15] in their wheat genotypes.

Table 4
) suggesting the slow transmission of genes in this trait.Our results are supported by the outcomes of Hussain et al. and Rashid et al. [9, 10].

Table 2 . Mean squares value for different characters evaluated during 2014-15 SOV DF Flag leaf area Plant height
*, ** = Significant at 5% and 1% probability level respectively

Table 4 )
[9]hese findings are in conformity with the results of Hussain et al.[9], who found that plant height was controlled by additive gene actions in their segregating population.