Study On Seeds Biological Characters And Seedlings Growth Process Of Iris L.

Iris L. is the largest and most evolutional genus in Iridaceae. Both life force and resistance in wild Iris are strong at the same time they keep green for long time. So Wild Iris have favourable foreground to large-scale extending. Finding out seeds biological characters and seedlings growth process of Iris will provide theoretic instruct and technical support for breeding, propagation as well as application in garden. In the thesis, we choose six wild species in northeast of China to study the configuration, physiological characteristic, peculiarity of dormancy and bourgeon as well as seedlings growth process. The results as follows:(1) Morphological difference of six species in Iris is obvious. The seeds can be distinguished by naked eye. The structure of I. ensata, I. pseudacorus and I. laevigata could make them floating on the water for a long time before they could germinate under a fitting condition. I.sanguinea and I. typhifolia have thin seed capsules and compact endosperms. The seed testa of I, lactea is thick and keratose. At the meantime, rigid endosperms enwrap the embryo. This is an important obstacle to germinate.(2) The difference of seed testa ultrastructure is notable. The figures of I. ensata, I. sanguinea, I. typhifolia, I. pseudacorus and I. laevigata are all reticular but the figure of I. lactea is alveolate. The latter is more evolutive than the former.(3) Most of mature seeds of wild Iris have activity. The activities of I. ensata, I. sanguinea, I. typhifolia and I. pseudacorus are steady in two years but the activities of/, lactea reduced by 13%. All the seeds of six plants are dank. The structures of endosperm and seed capsule of I. lactea are compact which is one reason lead to the low germination percent of seeds.(4) The adaptive temperature range of six species at which seed can germinate is rough consistent, i.e., 15C and 30C are not adaptive to germinate and the most adaptive temperature range to most species is from 20 C to 25 C. In addition, the alternative temperature change can redound to the germination of seeds in Iris.(5) Seedlings growth rule of Iris is as followed: Seedlings grow slowly from March (germination) to June. They have moderate vegetal speed during July. From August to October, seedlings growth speed is fast followed by a very slowly growth until december the growth stopped. Growth climax of roots lagged a month compared with the growth climax of seedlings.(6) Cotyledons of I.sanguinea, I. typhifolia, I. pseudacorus and I. laevigata seedlings only had basal but no ligular sheath. All these four species belong to commelina type. Basal and ligular sheath of I. ensata seedlings are all perfectly existed, and they belong to cyanotis type. I. lactea seedlings only remain ligular sheath and basal completely degenerated, and neck extend downward until completely joint with hypocotyl forming mesocotyl, which belong to cartonama type.(7) Among chosen plants species, light compensation point (LCP) and light saturation point(LSP) of I. lactea are higher than the others. So I. lactea is a typical light favor plant. LCP of I sanguinea is lower and LSP is higher which show that I. sanguinea is a shade sustainable plant. LCP and LSP of I. typhifolia both are moderate at light point. LCP is higer but LSP of I. ensata is lower so it can bear part time shade condition. LCP and LSP of I, laevigata are lower and the shade endurance is strong.