Combining Hybridization and Irradiation for Enhancing Genetic Variability in Early Segregating Generations of Safflower Crosses

 K.G. Parameshwarappa and R.D. Meghannavar

Abstract

An investigation has been carried out to assess the extent of genetic variability created and possible shifts which occurred in the association of eight quantitative characters in segregating generations of two safflower crosses, with populations generated by irradiation of 40 kr r-rays at F₀ stage (Irradiated series, F₂M₂ and F₃M₃) and untreated normal populations (Selfing series, F₂ and F₃). The number of capitula, capitula weight, seed number, seed weight, and oil content had a higher range and variance in the F₃ M₃ compared to the F₃ population. This is attributed to the release of hidden variability by irradiation at the early stage. Furthermore, there were also changes in inheritability values and genetic advance as seen by higher or lower values in both crosses.  The associations of most yield contributing traits with seed yield showed marked changes in degree and direction of correlations in the F₃M₃ population of both crosses. As a result of irradiation, the strong negative relationships existing between hull and oil content, and between seed yield and oil content were decreased.  Thus, additional variability created for some of the important yield traits coupled with shifts in correlations from negative to positive would offer greater scope for selection in the irradiated population.

 Key words:  Safflower, irradiation, hidden variability, associations