Turkish Journal of Biology




The objective of the present study was to determine the influence of artificial defoliation on sunflower seed yield, oil content, and fatty acid composition. The research was carried out at Süleyman Demirel University, Isparta, Turkey, during 2002 and 2003. Six defoliation levels [0 (control), 5, 10, 15, 20 and 25 leaves per plant] were applied at the preflowering stage from bottom to top leaves. The results demonstrate a close relationship between yield reduction and the defoliation levels. The higher the defoliation level, the higher the yield reduction. Complete and partial leaf removal treatments reduced oil percentage of seed when compared with the undefoliated check. However, oleic acid and linoleic acid levels in seed were not significantly affected by defoliation treatments.


Helianthus annuus L., leaf defoliation, yield, oil, fatty acids

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