| Betula luminifer is our country-specific broad-leaved species of fast-growing precious, it has a hi light, resistant to poor soil, fast-growing and better material properties. Selecting good clones has important theoretical and practical value. Ion Beam bioengineering technology has been considered as a new method for mutation breeding. With low-energy ions implanted into organisms, the biological effects and the function mechanisms of the technology were investigated by some researchers, and the technology has been used into genetic improvement and breeding of new varieties. In this paper, the mutation biological effects of the fast-growing tree species Betula luminifer by nitrogen ions were studied and discussed to provide some theoretical basis and experimental data for breeding of new varieties.In a vacuum degree of 7.0×10-3Pa under the conditions of the above, seeds of Betula luminifer 804#and Betula luminifer 874# were implanted by Nitrogen Ion Beam, energy was 30KeV/10mA, Pulse time for 2s, doses were 0×1016ions·cm-2, 1×1016 ions·cm-2,2×1016ions·cm-2,3×1016ions·cm-2,4×1016ions·cm-2,5×1016ions·cm-2,6×1016 ions·cm-2,7×1016ions·cm-2,8×1016ions·cm-2,9×1016ions·cm-2,10×1016ions·cm-2.We have studied their germination rate seedlings of the physiological and biochemical effects and etching the surface of the role of seed, The experimental results are as follows:1. After N+ion implantation the seed of Betula luminifer, the germination rate was reduced, present "saddle type" and survive in the curve, Germination rate, germination potential and dose showed significantly related, when the does improved to 6×1016ions·cm-2, germination rate rose to close to 0×1016ions·cm-2.2. By N+ion implanted, the chlorophyll content was reduced at the first, then ascension subsequent rapid decline, two clones of the sensitivity of ion implantation have to deal with a difference, Betula luminifer804# and Betula luminifer874# in the does of 6×1016ions·cm-2,7×1016ions·cm-2, chlorophyll content peaked respectively. It show that appropriate dose of the treatment that can induce the increase in chlorophyll content of seedlings to improve seedling potential photosynthetic capacity. 3. Analysis from the protective enzymes (POD, CAT, SOD), To deal with low-dose(1-3×1016ions·cm-2) serve as stimulus, with the does improved, cell injury severity, enzyme activity was inhibited. With the does 6×1016-7×1016ions·cm-2, the protective enzymes is more high. It can activate the synthesis of free radical scavenging ability of the enzyme the greatest degree of, Is conducive to coordinating role, so that free radicals remained at a lower level, from its violations of. In mutation breeding work, it is necessary to minimize the selection of high-dose, but the conditions of organisms into small injury, so that mutations can be more material.4. MDA and the conductivity was increased and then decreased again before the changes, Low-dose ion implantation processing plant cell damage, membrane lipid peroxidation enhanced. As the does improved, the seedlings to start the repair mechanisms, membrane system and function began to recover. In high does, repair-capacity reached its limit and it is irreversible, increased membrane damage, cell injury severity, functional destruction.5 The micro-structure analysis of implanted surface cell of seeds was done. The sputtering effect produced by ion beams implanting was researched. Moreover with the increase of the dose, the damage is not significantly.Taking all factors considered, Betula luminifer ion mutation breeding with N ion source; energy,30KeV/10mA;does,6-7×1016ions·cm-2 can enhance the activity of progeny seedlings, and it lay the basis of further study for Betula luminifer ion breeding.
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