Studies On Biological Characters Of Iris Dichotoma

Iris dichotoma Pallas is a wild flower in Iridaceae, which has blue-purple flowers, moderate height. It has strong tolerance to disease, heat and salt. It can survive in a wide range of habitat, suitable to be used in the gardens with poor soil. The systematic research on its growing periods and the biological character at every period can provide theoretic directions and technical supports in the fields of breeding, reproducing and its application in gardens. In this article, some researches on the seed configuration, seed germination and seedling growth process are done through experiments. At the same time, the process of its vegetative growth and reproductive growth are observed and analyzed in the thesis. The main results are as follows.(1) Iris dichotoma directly sowed outdoors, the first blade appears in May 17; The flower bud appears in June 13; flowers appear from July 31, up to blossom from August 3, entering the late stage from August 8; capsule ripes from September 11; the plant withers from November 14.(2) During the germination period, Iris dichotoma seed prefers sunshine and variable temperature, and it have relatively low water request while become rotten with excess water supply. The seeds have different germination ability at milk stage, dough stage and full ripe stage. Seeds at milk stage get rotten totally without ability to germinate; seeds at dough stage can germinate and have rather high germination rate; seeds at full ripe stage can germinate without dormancy, and the germination rate is up to 100%. There is little difference among the seeds in upper, middle and lower positions in the capsule.(3) The diurnal course of the photosynthesis is single-peak in all the three types of Iris dichotoma plants, perennials adopted the last year, adopted this year and the annuals. The peak values of the single-peak curves all appear at 10:00 am. Except 18:00, the photosynthesis rate of the three types follows this regularity: perennials adopted the last year> perennials adopted this year >the annuals.(4) Iris dichotoma flowers in the afternoon and the flowerage lasts about 5-6h. Insect pollination. The breeding system of wild Iris is mainly outcrossing, and incrossing partly.(5) Iris dichotoma has many characters, high germination rate and high germination speed, which other species in Iris don't have. The excellent character that it just flowers in the first year after being sown make it fit to quickly form landscapes at the application in gardens. In the salt-alkali earth of Anda city, Iris dichotoma can complete the whole process of sowing by itself, seedling, developing, flowering and fruiting. This proves it has some tolerance to drought, heat, cold, salt and alkali. The wild flower having high tolerance is suitable to be used in the gardens with poor soil.