Polyploid Induction Of Populus Ussuriensis Kom

Female catkins were treated with 0.2%-0.6% colchicine solution during 12-48hrs pollination in cross combinations between dialing poplar×weihe poplar, Some hybrids were obtained by treating the pollinated flowers with colchicine solution and without solution colchicines. Then the hybrids by treating the pollinated flowers without colchicine were treated with 0.1%-0.4% colchicine solution. After finishing the above process, sow all seed at the same time. Water and nutrients were managed during the whole growth.12 triploid (the pollinated flowers being treated with colchicine solution) and 24 tetrapioid(the seed being treated with colchicine solution) plants were obtained through chromosome numbering of the plant tip cell being conducted and DNA content in leaf cells being investigated. In order to investigate the reasons for differences among various ploidy Populus ussuriensis in growth traits, the comparative study on leaf structure and photosynthesis characteristics of two-year-old diploid, triploid and tetrapioid P. ussuriensis was examined.The results showed that:(1) 36-60 hrs after pollination was the optimal period and 0.5% colchicine solution was the optimal concentration to induce triploids in these cross combinations, and the highest ratio of obtaining triploids was 75%. The results showed that treated seed of Populus ussuriensis with 0.2% colchicine lead to a high mutationrate (up to 8.9%). leaves of the triploid and tetraploid seedlings were larger and thicker than those of the diploid ones, and the stomatal size and density on the leaf larger and thicker than that of the diploid respectively. The tetraploid plants exibited leaf length width and thichness are increased biggestr among different ploidy P. ussuriensis.(2) Different ploidy Populus ussuriensis are different significantly in contents of Soluble protein and chlorophyll, tetraplont Soluble protein content is higer 23% than dipolid, tetraplon chlorophyll content is higher 14% than dipolid. The difference of annual different ploidy populus ussuriensis is not significant in growth, The difference of biennial different ploidy populus ussuriensis is sifnificant in stem height,but not significent in basal diameter.(3) The comparative study on leaf structure and photosynthesis of two-year-old diploid, triploid and tetrapioid Populus ussuriensis was examined, in order to study the reasons for differences in growth traits. The results showed that net photosynthetic rate, light saturation point and compensation point among P. ussuriensis of different ploidy were significantly different. The value of the maximum photosynthetic rate from the triploid plant was 21% higher than the diploid.Triploid and tetrapioid P. ussuriensis were significantly increased in thickness of leaf, epidermis, palisade and ratio of palisade tissue to spongy tissue than the diploid.The sizes of upper and lower epidermal cells of the tetrapioid plant were the largest, the values of which were 64% and 17% higher than the diploid. The triploid plant had a maximum in the thickness of palisade tissue and spongy tissue and the ratio of palisade tissue to spongy tissue of the triploid plant was 50% higher than the diploid plant. With leaf photosynthenic characteristics and anatomical study performed, the results indicated that triploid and tetrapioid P. ussuriensis had a better acclimatization to light and photosynthesis compared to the diploid.