A field experiment was conducted with sunflower hybrid KBSH- 1 parental lines with six monthly sowings to predict the number of days to be staggered between the parental lines to achieve a synchronized flowering based on meteorological parameters. The regression study was made using the different heat unit concepts. The regression co-efficient between the phenophases and the derived weather parameters growing degree days (GDD), relative temperature disparity (RTD), helio thermal units (HTU) and photo thermal units (PTU) clearly indicated the variability between male and female lines with reference to the three phenophases studied. Among the phenophases, highly significant co-efficient was obtained for days to button formation and 50% flowering. Hence, from the study it was concluded that the computed regression equation could be employed to adopt suitable staggering to achieve proper synchronization to get higher seed filling and yield in sunflower hybrid KBSH-1 seed production.
Key words: Sunflower, hybrid parental lines, heat unit concepts, synchronization, flowering, equation.
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