A Comparative Study Of Biological Characteristics On Fagopyrum Dibotrys (D. Don.)Hara. And F. Esculentum Moench

Fagopyrum dibotrys (D. Don.) Hara. and F. esculentum Moench belong toFagopyrum in Polygonaceae. The former is a rare and endangered National GradeⅡ protected plant and the latter is widely cultivated as a grain crop. The anatomicalstructure characteristics of vegetative organs (including leaf, stem and root) of F.dibotrys and F. esculentum were observed using paraffin method, and the reasonwhy F. dibotrys is endangered was also discussed based on its structurecharacteristics. The anatomical characters of F. dibotrys and F. esculentum are asfollows: Their leaves are typically dorsi-ventral; between upper epidermis andmesophyll cells in leaves structure there are gaps in F. dibotrys, but no gaps in F.esculentum. The transverse section of petioles made of epidermis, cortex andvascular bundle are U-shaped. The vessels in the centre of petiole of F. dibotryslink to H-shaped and the petiole of F. esculentum have two vascular bundlesseparated by three-five parenchyma cells in centre. The vascular tissue which has asmall proportion in stem of two species contains developed phloem fibres. Hollowpith of old stem is bigger than that of young. Roots are made of epidermis, cortexand vascular cylinder. Primary vascular bundles in root are tetrarch. There aremany crystals in pith of root of F. dibotrys and few crystals in pith of root of F.Esculentum. Some structure characteristics showed that F. dibotrys has low coldresistance and low drought resistance, maybe this is the reason for F. dibotrys tobecome endangered.We studied their reproductive biology characteristics from the aspects ofphenology (anthesis), floral traits, pollen viability, seed sets, seed germination rateand flower visiting insects. The results showed that: F. dibotrys and F. esculentumare stablely distylous in morphology. The anthesis of long-styled and short-styledflower of F. dibotrys lasted13-14d and12-13d respectively. The anthesis oflong-styled and short-styled flower of F. esculentum lasted24-38d and24-42drespectively. The pollen-ovule ratio (P/O) of long-styled flower and short-styledflower of two species are different, but their P/O are all between244.7-2588.0, so the breeding system of two species are mixed with self-pollination and outcrossing.Their pollen grains are long spherical. Short-styled pollen grains of two species arelarger than long-styled pollen grains. Long-diameter and short-diameter oflong-styled pollen grains of F. dibotrys are respectively50.3±1.9μm and29.0±1.1μm. Long-diameter and short-diameter of short-styled pollen grains of F.dibotrys are61.6±0.8μm and36.2±1.3μm respectively. Long-diameter andshort-diameter of long-styled pollen grains of F. esculentum are46.7±1.1μm and26.9±0.5μm respectively. Long-diameter and short-diameter of short-styledpollen grains of F. esculentum are61.9±1.6μm and36.3±1.3μm respectively. F.esculentum has higher pollen viability than F. dibotrys. The pollen viability oflong-styled and short-styled pollen grains of F. dibotrys are38.2±4.3%and39.3±3.0%respectively. The pollen viability of long-styled and short-styled pollen grainsof F. esculentum are73.1±3.6%and72.6±3.7%respectively. Short-styled seedsof two species are smaller than long-styled seeds. The average weight oflong-styled and short-styled seed of F. dibotrys are0.067±0.0008g and0.057±0.0007g respectively. The average weight of long-styled and short-styled seeds ofF. esculentum are0.035±0.0002g and0.033±0.0003g respectively. Seed sets oflong-styled and short-styled plant of F. dibotrys are9.2±0.46%and9.8±0.54%respectively. Seed sets of long-styled and short-styled plant of F. esculentum are75.9±1.19%and76.7±1.19%respectively. Seeds of F. dibotrys are sensitive totemperature, and low temperature is suitable for germination and the rate of seedgermation is75.8%at10℃. Seed germination rate of F. esculentum is97.5%at25℃. F. dibotrys is a perennial herb and it is mainly reproductived by root in nature.It is very significant to protect F. dibotrys by studying its endangeredmechanism. The endangered mechanism including external factors and internalfactors were preliminary analyzed in this paper and some protection strategies forthis species were put forward:(1) Strengthen propaganda, enhance consciousness,set up nature reserve;(2) Use reproduction and expand planting areas;(3) Towardthe domestication of nature;(4) Enlarge the studies on sexual reproduction. Thisstudy has provided an important example for protecting endangered species inChina.