Abstract
Studies were conducted to assess the agronomic kg ha-1and physiological basis of variation in yield among three
sunflower hybrids of varying maturity groups, sow at row spacing of 45, 60 and 75 cm during the autumn seasons
of 2006 and 2007. In both years of experimentation, the hybrid Hysun-33, a long season hybrid, stood out not only
for maximum leaf area index, but also for its crop growth rate, plant height, number of achenes and achene yield.
Hysun-33 produced significantly higher achene yield (3033 kg/ha), planted at the 60 cm apart rows, followed by
SF-187 (2783 kg/ha), when sown at 45 cm apart rows. The minimum yield was recorded, when FH-331 was sown
at 75 cm apart rows. Although, head diameter, number of achenes per head, 1000 achene weight increased with
increasing row spacing from 45-75 cm, but the increase in yield with narrow rows was largely related to increased
achene number, higher leaf area index and maximum crop growth rate.
