Abstract
Two field experiments were conducted at the University of Arid Agriculture, Rawalpindi, Pakistan during autumn,
2003 and spring, 2004 to document relationship of heat units accumulation and fatty acid composition in
sunflower hybrids. Five sunflower hybrids (Super-25, Parsun-1, SMH-9706, Award and Hysun-33) were sown on
ten planting dates both in autumn and spring. Experiments were laid out in randomized complete block design
with split plot arrangements replicated four times. Planting dates were kept in main plots and hybrids in subplots.
Sunflower hybrids exhibited significant differences for heat units accumulation and fatty acid composition. During
autumn, amongst hybrids Hysun-33 accumulated the maximum heat units which was statistically significant from
rest of the hybrids. During autumn, amongst hybrids Hysun-33 performed better for oleic acid while Award
remained at the top for palmatic and linoleic acid. However, during spring, Super-25 accumulated the highest
linoleic acid while Hysun-33 was the best for stearic and oleic acid. Planting dates also influenced fatty acid
composition significantly. Overall, spring plantation accumulated higher oleic acid in comparison with autumn
planting. However, autumn planting accumulated higher linoleic acid which depicted an inverse relationship of
oleic and linoleic acid. During autumn, late August planting accumulated the maximum linoleic and the minimum
oleic acid. Duringspring, late April planting exhibited the highest oleic and least linoleic acid.
