Research On Propagation Characters And Genetic Diversity Of Iris Lactea Pall.var.chinensis (fisch.) Koidz

Combined with both field observation and laboratory test methods, the propagation characters of Iris lactea, were studied based on the experiments from different levels such as biology, physiology, cytology, embryology and genetics. The framework of this dissertation is the propagation cycle of Iris lactea, which begins from seeds germination and end in the formation of new seeds. The main contents including: to develop new knowledge of the mechanism of seed dormancy and new techniques to breaking seed dormancy, features of Iris lactea on flowering biology and pollination biology, breeding system of Iris lactea, genetic variation analysis of its agronomic traits and ISSR marker in different ecological regions and so on. The dynamic changes of chemical and physiological process during seed germination, florescence, pollen, fertilization were observed and analyzed; In-depth research on the Iris lactea mechanism in terms of its seed dormancy were going to find dormancy breaking technology and determine appropriate germinating conditions; The genetic diversity and relationship among populations of Iris lactea were studied, from the level of agronomic traits and DNA molecular, which come from 20 different regions in Inner Mongolia. The results of the above tests completed will establish developing system theory basis for Iris lactea .The main conclusion were as follows:1. Due to immature embryo, the fresh seeds of Iris lactea were in the state of after-ripening with low germination ability under wild conditions. One of the key reasons of seed dormancy was the thick seed coat, which covered 31.7% of total seed weight and inhibits the growth of embryo during seed germination. Moreover, no inhabitation chemicals of soaking liquid of seed coat and albumen which meaned that the seed dormancy of Iris lactea was spontaneous. Stratification and soaking for 8 hours in 40% NAOH were effective methods to improve the germination of Iris lactea seeds.2. There were 15 to 55 flowers per plants with 35 days of florescence. There was no significance difference of data to the initiation, peak and ending of florescence between different years. The florescence was mainly affected by such factors as temperature, light and humidity. Moreover, the number of flowers and seeds was negative related to the date of flowering. The number of flowers had positive relation with the number of seeds.3. The vigor of pollen was highest on the 9:00～10:00 a.m during the day. After that, the vigor of pollen began falling which falled to 9.85% at 6:30 p.m. The storing environment had great effect on the vigor of pollen. The Iris lactea was the plant of self incompatibity, which was pollen by insects. The elimination of valve was one of effective isolation pathways.4. The double fertilization of Iris lactea was achieved through the special channel provided by the pollen tube. The type of endosperm development belongs to nucleolus type. It required about 60 days from florescence to seed ripeness. There were 1~4 seeds per anthotaxy. Capsule had a beak on its top, with 3 splits pre capsule. There were 50 seeds per capsule. The production of seed and biomass was determined by the number of tiller buds.5. Agronomic traits of Iris lactea populations showed abundant variation. There were 10 main characters that caused variation among populations from different sources, including grain weight, germination rate, water absorption, the embryo length, endosperm length, seed length, fertile tillers, vegetative shoot, leaf width, plant height. Embryo length, grain weight, water absorption are affected easily by environmental factors. Clustering results showed that the majority of population materials showed significant regional sources. If longitude and latitude of population materials were similar, then they clustered together.6. Genetic diversity of Iris lactea showed rich. The percentage of polymorphic bands was 91.1% from different sources. 20 populations were divided into four major groups by UPGMA clustering. Genetic relationship among populations was significantly correlated with its latitude, and there was a certain correlation with their habitats. The above ISSR research results agreed with the above agronomic research. Furthermore, ISSR-PCR amplification reaction systems of Iris lactea established.