Inheritance of grain filling duration in spring wheat

The genetic basis of grain-filling duration (GFD, days from anthesis to maturity) in six spring wheat hybrids involving nine varieties ('Sonaiika'/'Bobwhite', 'Sonalika'/'Glennson 81', 'Lelija'/'Bobwhite', 'Lelija'/'Mitacore', 'Buckbuck'/'Dugoklasa', and 'Vesna'/'Radusa') and their F-1, F-2, BC1, and BC2 generations was studied in the field near Sarajevo, Yugoslavia. Parental means differed in four of the six crosses. Generation mean analyses of genetic effects indicated that an additive-dominance model was sufficient for only two crosses: Lel/Bow and Lel/Mco. One or more types of epistasis were significant in the remaining crosses. The F-1 and F-2 means were either intermediate, closer to the mean of the parent with the longer GFD, or closer to the mean of the parent with the shorter GFD. Even though different modes of gene action controlled GFD among the six crosses, the heritabilities were reasonably high (narrow sense, 40-60% range for six crosses), indicating that progress could be made from selection in these crosses for either long or short GFD. The parents were selected to have a range in days from planting to anthesis and to maturity. The relationship between dates of anthesis or maturity and GFD was not consistent, but the two latest-maturing varieties had the longest GFD, indicating that anthesis or maturity dates are not a good criteria for choosing parents for modifying GFD. Additive genetic effects predominated in the crosses studied here, but epistasis involving dominance gene action was sufficiently important. Tb eliminate confounding epistatic dominance effects and to take advantage of favourable additive x additive effects during selection for GFD, a breeding strategy involving rapid approach to homozygosity followed by selection after the achievement of homozygosity was suggested.