Changes in Essential Oil Yield and Composition at Different Parts of Dill (Anethum graveolens L.) Under Limited Irrigation Conditions

        The influence of water stress during vegetative and reproductive growth stages on essential oil yield and composition of Iranian dill was evaluated in 2006 and 2007 at the Research Farm of Faculty of Agriculture of the University of Zanjan. Experiments were carried out as split plat design based on randomized complete block in four replications. Irrigation treatments were allocated to main plots and harvest times were assigned to sub plots. Irrigation treatments were full irrigation (control) to achieve  100% of field capacity (FC) during the growth season, two moderate (66% of FC) and two severe (33% of FC) water stresses during vegetative and reproductive stages. Three harvests were carried out at vegetative, full flowering and seed maturity stages. The essential oil contents of the leaves (H₁), flowering shoots (H₂) and  mature seeds (H₃)  were isolated by hydro distillation and analyzed by GC and GC/MS. 24, 29 and 25 compounds were identified from leaves, flowering shoots and seeds respectively. Both moisture availability and harvesting times had significant effects on essential oil content. The percentage and yield of essential oil contents of seeds (H₃) and flowering shoots (H₂) were much higher than those of leaves (H₁) under all irrigation treatments. Essential oil percentage of leaves was increased with decreasing water availability. However, essential oil percentages of seeds and flowering shoots were considerably high, when plants were subjected to moderate and severe water deficit at different developmental stages. In contrast, the highest essential oil yield (6.146g/m²) was obtained from flowering shoots under moderate water stress during flowering and seed filling phases (S₃H₂), while the lowest essential oil yield (0.216 g/m²) was produced from leaves under severe water deficit during early growth stage (S₂H₁) in both years. The main oil constituents of the leaves and flowering shoot were α – phellandrene, β – phellandrene and β – pinene, while that of seeds oil was carvone (70.78%). The amount apiol increased under severe stress, while carvone content increased under moderate stress. The quality of β – phellandrene was unaffected by irrigation treatments, but  the amount of α – phellandrene decreased under moderate and severe water stress. le='mso.� cr
h�f ]] �( g/m²216/0) در برگ­های گیاهانی تولید شد که در مراحل اولیه رشد در معرض تنش شدید خشکی (S₂H₁) قرار گرفته بودند. آلفا ـ فلاندرن، بتا ـ فلاندرن و بتا ـ پینن اجزای اصلی تشکیل دهنده اسانس برگ­ها و سرشاخه­های گلدار بودند، در صورتی که ترکیب اصلی اسانس دانه­ها کاروون (78/70 %) بود. میزان آپیول در اثر تنش شدید خشکی افزایش چشم­گیری یافت، در حالی که کاروون تحت تنش­های ملایم خشکی زیاد شد. میزان بتا ـ فلاندرن تحت تاثیر تنش کم آبی  قرار نگرفت، ولی مقدار آلفا ـ فلاندرن تحت تاثیر تنش­های ملایم و شدید کاهش یافت.
 
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h�f ]] _CompsetB;mso-bidi-font-family:"B Yagut"'> برارپور م  ت، منسوجی ع و بابائیان جلودار ن، 1381 . اثر آللوپاتیک مقادیر و سنین مختلف بقایای آفتابگردان بر سبز شدن و رشد پنبه. علوم کشاورزی و منابع طبیعی گرگان سال نهم ، شماره اول. ص54.
 
 محسن زاده س . 1379. اثرات آللوپاتی گیاه قیاق (Sorghum  halepense) و مرغ پنجه­ای (Cynodon  dactylon) بر گندم. علوم کشاورزی و منابع طبیعی گرگان، سال هفتم ، شماره دوم، .صفحه47-54.
میقانی  ف ،1382 .آللوپاتی (دگر آسیبی ) : از مفهوم تا کاربرد. انتشارات پرتو وا قعه.
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