IARI Regional Station, Hyderabad, 500 030, India
1Present address: Project Coordinator (Millets), College of Agriculture, Pune, Maharashtra State.
Intra- and inter-population improvement were initiated n sunflower to increase and stabilise the decreasing seed yields, seed set and oil content. Three cycles of selection were effected in three populations. They are: SF-1A involving an F1 hybrid between two inbred lines; SF-2, the reconstituted EC-69874 and SF-3 involving a cross among four open-pollinated varieties.
Oil content consistently increased in all the populations, while the response to selection for seed yield was variable. Seed yield decreased in SF-1A and SF-2 in cycle 2 and then increased in cycle 3. The response to selection for seed yield in SF-3 is greater in cycle 3 than in cycle 2. Oil content rose steeply in SF-1A and SF-3 in cycle 2 but thereafter the rate of increase slowed down.
The rate of response to selection for oil content is slower in SF-2 which has initially more, oil than the other two populations. Variation for oil content is maintained in SF-1A and SF-3, while it is decreasing in SF-2. All the populations exhibited variability for seed yield. These results could be related to initial diversity in the populations and their past history of selection.
The advantages of population approach (against hybrid approach) under current circumstances have been pointed out. The significance of the population breeding in stepping up yield, seed set and oil content of released varietal populations through reconstitution and selection has been discussed.
