Abstract
A diallel analysis of wheat (Triticum aestivum L. em. Thell) parents (n = 11) and their F1 (n = 55) and F2 (n = 55) offspring was carried out for the following four traits: grain filling duration (GFD), GFD for growing degree days (GDD), 1000 seed weight and seed yield per plant. Analysis of variance for general combining ability (GCA) and specific combining ability (SCA) displayed significant F1 and F2 general and specific combining ability effects for the four traits studied. For all the traits the GCA effects were relatively more important than the SCA effects, indicating that additive genetic effects were predominant. Crosses displaying high SCA effects for grain filling duration, seed weight and yield were observed to be derived from parents having various types of GCA effects (high x high, high x low, low x low and medium x low). The single seed descent method can be applied to exploit additive gene effects whereas dominance gene effects could be valuable in hybrid wheat breeding programs. Among the parents, genotypes from the International Maize and Wheat Improvement Center (Centro Internacional de Mejoramiento de Maiz y Trigo, CIMMYT) as well as South Asia were found to be superior general combiners for grain filling duration. Likewise, crosses involving diverse parents from CIMMYT and South Asia showed significant SCA effects for grain filling duration and other traits.
Highlights
The most important yield components of wheat
The coefficient of variation was highest for seed yield, followed by growing degree days and grain filling duration (Table 2)
For both the F1 and F2 generations the general and specific combining ability Analysis of variance (ANOVA) results for all four traits were significant (Table 3), with the general effects being higher than the specific effects
Summary
The most important yield components of wheat (Triticum aestivum L. em. Thell.) are number of kernels per spike and Kernel weight, the latter being the product of the rate and duration of grain filling (Gebeyehou et al, 1982; Van Sanford and Mackown, 1985; Bruckner and Frohberg, 1987). *Present address: Centre for Transgenic Plant Development, Department of Biotechnology, Hamdard University, New Delhi, India Both influence the rate and duration of grain filling (Gallagher et al, 1974; Metzger et al, 1984; Bauer et al, 1985) and significant genotypic differences for this trait have been reported in spring wheat (Mou and Kronstad, 1994; Przulj and Mladenov, 1999; Saadalla et al 2000; Talbert et al 2001). Almost the whole of this late sown area is in the eastern Gangetic plains, most of which occurs in the 9.5 million hectare North Eastern Plain Zone (NEPZ) of India where the average wheat yield is only 2.7 tonnes (t) ha-1 compared to the 4.7 t ha-1 in the Indian state of Punjab (Joshi et al, 2007b).
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