This study was conducted in an effort to evaluate the effect of two gibberellin biosynthetic inhitiors, mepiquat chloride (MC 200, 400, 600 ppm) and trinexapac-ethyl ethyl (TNE 100, 200, 300 ppm) on flax (Linum usitatissimum L.) seed oil composition, growth characteristics and seed yield when applied at vegetative stage. A foliar spray of 600 ppm MC was found to be most effective, resulting in decreased plant height, and an increased seed yield (1,963 kg ha-1) with highest oil content (37.2 %). Ripened seed rate ranged 90.2 –91.9% in MC treated flax and 93.7- 94.1% in TE treated flax, respectively. MC treatment increased seed yield 10.9 – 21.6% and TNE treatment also increased 7.9 –11.8% compared to the control. The significant increase of flax seed yield in MC treatment was observed 600 ppm between these concentrations. Two gibberellin biosynthetic inhibitors, MC and TNE were 1.6 – 5.5% more ripened compared to the control. An increased unsaturated fatty acid was observed when higher concentration was applied to flax plant. Endogenous GA4 content was always higher than GA1 content in both MC and TE treatment.

• Sang-Kuk Kim(Division of Crop Science, Gyeongsabuk-do Provincial Agricultural Technology Administration)
• Hong-Jib Choi(Division of Crop Science, Gyeongsabuk-do Provincial Agricultural Technology Administration)
• In-Jung Lee(Division of Plant Biosciences, College of Agriculture and Life Science, Kyungpook National University) Corresponding author