Results
The 50 fennel landraces varied considerably for total oil content (Table 1; Figure 2), ranging from 9.5 to 23% of dried ripened seed mass. The average oil content was 13.45±0.44% among early maturity landraces, 17±0.74% among medium maturities, and 16.7±1.08% among late maturities. The highest oil contents among early maturity types belonged to Hamedan, Arak, and Mahalat landraces with 19.55±1.15%, 18.5±0.86%, and 17.5±0.26%, respectively. Among medium maturities, the Marvdasht, Kohn, and Meshkin Shahr landraces had the highest oil contents with 23±1.7%, 20.5±0.58%, and 19±0.27%, respectively, and among the late maturity fennels, Sari had the highest oil content with 21±0.57%.
Using seed yield data from one of our previously published works (Bahmani et al, 2015), and total oil content data in this study, oil yields (ml/m2) for the 50 landraces were estimated (Figure 3). Among late maturity fennels Sari landrace (71.4 ml/m2), among medium maturities Meshkin Shahr and Moqhan landraces (92.4, and 85.4 ml/m2, respectively), and among early maturities Fasa, Saqez, and Rafsanjan landraces (65.3, 49.8, and 44 ml/m2, respectively) were the highest oil-yielding landraces.
Oil percentages of the twelve seed samples brought to Michigan State University were similar to the results from 2012. Oil compositions of the twelve landraces were quantified by GC-MS (Table 2). Sixteen different fatty acids were identified, which constituted 99.5% of the total oil in the samples. Among these, the most abundant fatty acids were oleic acid (52-64%), linoleic acid (26-39%), palmitic acid (0.3-4.1%), linolenic acid (0.6-3.6%), stearic acid (1.3-2.4%), and myristic acid (0.35-1.07%), arachidic acid (0.12-0.83%) and lauric acid (0.15-0.58%). The highest amounts of oleic acid belonged to the Khash, Fozveh, and Arak landraces; and the highest amounts of linoleic acid to Meshkin Shahr and Sari landraces.
The mean percentage of unsaturated fatty acids among the twelve landraces was 91.55±0.54% of the total oil content (Table 2; including 59.43±1.33% monounsaturated fatty acid, mostly oleic acid, and 32.12±1.37% polyunsaturated fatty acid, mostly linoleic acid), while the mean saturated fatty acids was 7.67±0.63%, which mostly was composed of palmitic acid and stearic acid.
The twelve fennel landraces were grouped based on their fatty acid profiles (Figure 4; Table 3), which yielded two groups. Group 1 contained higher contents of oleic acid (62.3±0.95%), stearic acid (1.91±0.11%), arachidic acid (0.47±0.070%), and palmitic acid (3.24±0.16%) than group 2, while group 2 contained higher contents of linoleic acid (34.95±1.23%), and linolenic acid (2.13±0.38%). Landraces included in group 1 (oleic acid chemotype) originated from regions with a dry and warm climate (Eastern Zagros Mountains, and southern Alborz mountains), while the landraces in group 2 (linoleic acid chemotype) originated from regions with a humid and cool climate (the western Zagros Mountains, and northern Alborz mountains).