Seed Germination And Parasitic Relationship Of Cynomorium Songaricum And Nitraria

Cynomorium songaricum Rupr., a precious traditional Chinese parasitic medicine, mainly parasitizes in the roots of Zygophyllaceae and Nitraria L. in desert areas typical of Hexi, Gansu. Nitraria tangutorum Bobr. and Nitraria sibirica Pall. are perennial eremium shrubs of Zygophyllaceae Nitraria L. The study aims to solve the problem of low germination rate of the three eremium seeds under natural conditions through physical and chemical methods to break dormancy and promote after-ripening. Three methods were used respectively to inoculate year-old seedlings, cuttings and three-year-old seedlings with the purpose of providing theoretical basis for artificial Cynomorium songaricum Rupr. cultivation by probing into the effects of Cynomorium songaricum Rupr. on establishing parasitic relationship with Nitraria. The major findings are as follows:(1) Storage time and gibberellic acid had a significant effect onCynomorium germination rate. Seeds stored at room temperature (24℃-28℃) for six months had a highest germination rate (30.5%); whereas those stored at room temperature for12months (22.4%) and24months (16.4%) had no significant difference in germination rate; the lowest germination rate (13.0%) was found in seeds stored for36months at room temperature. With the growth of the storage time, the germination rate of cynomorium was decreasing. The seed germination rate of Cynomorium songaricum Rupr. with50mg/L GA3treatment (45.5%) and with25mg/L GA3treatment (5%)had no significant difference, but compared with those with75mg/L GA3treatment (11.0%) and with100mg/L GA3treatment (5%), the difference was very significant. Therefore, storage at room temperature with50mg/L GA3treatment is in favor of improving the seed germination rate of Cynomorium songaricum Rupr..(2) For Nitraria tangutorum Bobr. seeds, different storage conditions meant different germination rates; the germination rate of the changing temperature (64.7%)(low temperature storage for three months and room temperature storage for another three months)storage seeds was significantly higher than those stored at normal temperature (40.0%) and at low temperature after acid treatment. The germination rate of fresh seeds was the lowest(18.2%). The germination rate of changing temperature storage seeds with0.5mol/L NaOH solution was the highest(66.0%); there was significant difference between room temperature storage seeds and those stored at low temperature; the fresh seeds the lowest. In sum, changing temperature storage is good for breaking dormancy of Nitraria tangutorum Bobr. seeds;0.5mol/L NaOH solution can get rid of the hard seeds. The two combined can significantly improve seed germination rate.(3) Storage method and time have a significant effect on seed germination rate of Nitraria tangutorum Bobr.. The germination rate of the seeds stored at room temperature (24℃-28℃) for2years (61.3%)was significantly higher than those stored for one year(29.4%) with sulfuric acid treatment; fresh seeds the lowest(3.3%). The germination rate of the seeds stored at room temperature for2years was the highest (74.6%) with0.5mol/L NaOH solution; there was significant difference between seeds stored at low temperature for one year (32.0%) and fresh seeds(5.0%); no seeds stored at low temperature spouted in the testing time. Therefore, the low temperature is not propitious for Nitraria tangutorum Bobr. seed storage; storage at room temperature for2years and treatment with0.5mol/L NaOH solution can effectively improve the seed germination rate.(4) The germinated Cynomorium seeds were directly inoculated in the root of the host in early May after breaking their skins. When observed in October of the same year, no established parasitic relationship was found between the seedlings and the host; for those cuttings, there were papillae in the inoculated roots; for three-year-old transplanted seedlings, there were tumor-like protuberances in the inoculated roots. Other inoculation methods cannot establish a parasitic relationship between Cynomorium seeds and their hosts.This study was to explore technical ways to increase seed germination rates of the three desert plants, which is significant in protecting and restoring desert vegetation resources and natural ecological environment. The method of breaking the skins of germinated Cynomorium seeds generates direct establishment of the parasitic relationship between the seeds and three-year-old transplanted Nitraria seedlings in their roots, which provides theoretical and practical basis for artificial cultivation of precious parasitic Chinese herbal medicine.