| Estimation of genetic effects for agronomic traits
in wheat by K.H. GAMIL* and Y.A. AL-SAHEAL** * Fac. of Agric., Minia Univ., Minia, Egypt and ** Fac. of Agric. in Kassem, King Sauid Univ. The most efficient breeding procedures and the expected gain from selection for quantitative traits depond upon the magnitude of gene effects and their mode of action. Many workers developed genetic model for the estimation of different genetic effects (MATHER 1949, HAYMAN 1958, GAMBLE 1962 and others). SUN et al. (1972) by using six-parameter model found that epistasis was affecting in the inheritance of kernel weight. Regarding yield and plant height, CHAPMAN & MC-NEAL (1971) found highly significant epistatic effects. AMAYA et al. (1972) found that dominance effects were relatively more important than additive in the inheritance of yield but the additive effects were predominant for plant height and heading date and they detected epistatic effects in some crosses. MATZINGER et al. (1960) noted that failur to include epistatic effects in heritability estimate may bias estimates of additive genetic variation and prediction gain from selection. In the present investigation a cross of two hexaploid wheat cultivars was made to obtain information about heterosis, the nature of gene effects, heritability and genetic advance under selection for the more importnat agronomic traits. Materials and Methods The experimental populations in this investigation were derived from crosses and backcrosses of Samma (Saudi) and Super-x (Mexican) wheat cultivars. Crosses between parents were made in the green-house in season 1979, and the F1 was backcrossed in 1980 to each of the parents (P1 and P2) to produce the first backcross generations B1 (P1 x F1) and B2 (P2 x F1). The parental cultivars, F1, F2 and backcrosses were grown in a randomized complete block field experiment with three replications at Faculty of Agriculture (Olisha), King Sauid University in season 1981. With each replication the non-segregating generations composed of one row, two for each backcross and four for the F2. Each rows were 4 m long, 50 cm apart and seeds were space-planted 20 cm allowing a total of 20 plants per row. The data were obtained on each plant for the following traits: Date headed: Number of days from sowing to the day when spike of tallest culm was fully exserted from the flag leaf sheat. Plant height: Height in centimeters from the soil surface to the base of the spike of tallest culm. |
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