Flower Biology Study On Three Species Of Iris In Northwest China

There are rich wildlife resource of Iris in China. Iris tectorum, I.bungei and I.tenuifolia were herborized from the northwest China. Through the seed germination characteristic, the ontogenesis rhythm, the blossom and pollination characteristic, the root and leaf dissection structure, the photosynthesis characteristic research and the nuclear type analysis, get conclusions as follows.1. The seeds of I. tectorum do not have dormancy, and the seed germination percentage achieved 91.35% in 20℃. The seeds of I.bungei and I.tenuifolia have the deep dormancy, and seed dormancy can't be removed by GA₃ and cold stratification. The seed germination rate of I.bungei and I.tenuifolia can raised effectively through the oil of vitriol sour erosion 60 minutes, which wasfrom 1.1% and 0.5% to 45.5% and 51.4%.The suitable temperature of germination was 20℃ for the three Iris species.2. The three Iris species seedlings were all cotyledon stay soil. The fast growth period of the seedling leaves was from August to October in Beijing. The adult plant leaves growed main concentration after spending. From June to August, it is the fast growth period of the adult plant.3. Flower buds of I. tectorum differentiated rapidly in October, and early in November flowering organ had formatted. In August, flower buds of I.bungei and I.tenuifolia differentiated rapidly, and at the beginning of September flowering organ had formatted. Because of the special structure of its flowered organ, I. tectorum can't be fertilized by its own pollen. Bee was pollinating insect. The role of the falls was very substantial. If they were broken off pollination did not occur, although insect pollinators were present.4. The root system of I. tectorum was shallow and assumed horizontal distribution, while the root system of I.bungei and I.tenuifolia was deep and assumed vertical distribution. The number of the first formed xylem of I.tectorum , I.bunge and I.tenuifolia was 12, 10 and 9. Mesophyl cell differentiated for palisade tissue and spongy tissue in all the other two species except I.tectorum.5. Early in September, diurnal changes in net photosynthetic rate(Pn) of the three Iris species were a typical bimodal curve. The light saturation point(LSP) of the three Iris were 383.9, 593.1, 684.8μmol·m^-2·s^-1, whilst the light compensate point(LCP) were 21.9, 28.4, 37.9μmol· m^-2·s^-1. LCP and LSP of I.tectorum were lower, which showed that it was a shade sustainable plant. LCP and LSP of I.bungei and I.tenuifolia were higher, so they were a typical light favor plant.6. The karyotype formulae of I.tectorum was 2n=30=12m(2SAT)+16sm(4SAT)+2t, belonging in Stebbins's 2B type; The karyotype formulae of I.bungei was 2n=32=30m+2sm, belonging in Stebbins's 1B type; The karyotype formulae of I.tenuifolia was 2n=14=6m+8sm(2SAT), belonging in Stebbins's 3 A type. 7. In cultivations, the three Iris species can reproduce through seeds in autumn or spring. Before sowing, the seeds of I.bungei and I.tenuifolia should had to be put in oil of vitriol for 60 minutes. I. tectorum was suitable reproducing through rhizomes in the beginning of spring or after blossoming, while I.bungei and I.tenuifolia were not. Because I.bungei and I.tenuifolia resists drought and bears infertile, they can growed well through be applied poor fertilizer and water. The abilities of counteracting disease and inset of the three Iris species were stronger, so they did not need the fine plant disease management.Grasping the plant growth process and biology characteristic, can provides the basic research for the garden application, the breeding and expands numerous.