بررسی برخی از جنبه های مرفولوژی و بیولوژی ریشههای غدهای و بذر علف هرز مهاجم فیکاریا (Ranunculus ficaria L.)

Introduction: Ranunculus ficariais L. (Fig buttercup or Lesser Celandine) is an herbaceous perennial belongs to Ranunculaceae (buttercup family) that behaves as a ground cover. It is a spring ephemeral that grows from a cluster of tuberous roots in late winter or early spring. It has glossy, dark green (sometimes slightly mottled), fleshy leaves on long petioles, and cordate to oblong-cordate in shape. The margins can be entire or wavy (1, 28). Flowers 15-60 mm in diameter, solitary at the end of each stem branch. Flowers have 3 sepals (rarely more), 3 petals, bright, pale to golden yellow, very rarely orange, shining on inside, receptacle concave, with short, pale simple glandular hairs. Achenes either abortive or maturing in a globular cluster, when mature 2•5-5•0 x 1•7-3•5 mm, more or less globular or obovoid, usually with few to numerous very short simple glandular hairs. This invasive weed spreads primarily by vegetative means through abundant tubers and bulblets, each of which can grow into a new plant once separated from the parent plant. The prolific tubers may be unearthed and scattered by the digging activities of some animals, including well-meaning human weed pullers, and spread to new sites during flood events (28). This weed has two subspecies, R. ficaria Subsp. ficaria and R. ficaria Subsp. bulbilifer that the second is probably the only subspecies of mountainous regions in many areas. It is an abundant weed of lawns and gardens, where it spreads rapidly and is very difficult to eradicate. According to our observations probably R. ficaria spread by tubers from mountains to fields that near to mountains in Lorestan province of Iran. The Aim of this study was assessment of this weed to improve its management practices in the wheat fields. Materials and Methods: In order to study the some aspects of biology and morphology of tubers root and seeds of R. ficaria , two experiments were conducted at Laboratory of Gorgan University in 2011. For breaking root tubers dormancy, root tubers incubated for different storage time (7, 14, 21 and 28 days) and different storage temperature (2, 4 and 8˚C). To evaluate the effect of tuber size, six groups (very small <0.02 G, small 0.03-0.04 G, tall 0.1-0.27 G, medium 0.06-0.12 G, group 0.15-0.64 G and half 0.07-0.18 G) of tubers were incubated at 14˚C. Tubers root morphology was assessed by field and greenhouse observation. Seeds after being in the fridge at least two weeks, investigated the germination of them at 14˚C and seed structure was study by binocular observation. Results and Discussion: The results showed that the highest percentage of germination occurred in tubers which were stored more than 2 weeks at 4 or 8 ˚C. No significant differences were observed neither between 4 and 8˚C in storage temperatures nor among the different durations of storage. Tuber dormancy of R. ficaria is broken by chilling (11, 28). Germination of the fingerlike group and small tubers was the highest (95%), however, very small, small and broken tubers indicated the lowest germination percentage. Germination rate were 0.6 and 0.5 tuber per day in fingerlike group and small size of tubers root, respectively. Tuberous roots were aggregate and fingerlike shape, with different size; these tubers are divided to separate units by disturbing the soil after mother’s plant dies. Each tuber can produce a new plant. Ficaria’s seeds contain mucilage and it seems that the second cotyledon of seed has dwindled. Seeds did not germinate; it would be related to seed infertility due to non-viable pollens. The flowers are self or insect pollinated, self-pollination occurs in the absence of insects. However, much of the pollen of bulbifera is non-viable (4). Lesser celandine is unusual for a dicotyledon in having seedlings with a single cotyledon (4, 29). Conclusion: Maintaining tubers for more than 2 weeks at 4 or 8 ˚C broke dormancy and take place germination of tubers. Germination rate was the highest in the fingerlike group and small tubers. Seeds of R. ficaria did not germinate; it would be due to seed infertility. The seeds contain mucilage and it seems that the second cotyledon of seed has dwindled. According to our results maybe this weed is sub-species of bulbifera.