Study On Tetreploid Induction Of Cucumis Melo L. With Colchicine

The experiment were done in Guangxi Crop Genetic Improvement and Biotechnology Lab, Agricultural College of Guangxi University Vegetable Lab and Scientific Research base of Horticulture Research Institute of Guangxi Academy of Agricultural Sciences from 2006～2008. The diploid cucumis melo L. seeds were provided by Horticulture Research Institute of Guangxi Academy of Agricultural Sciences .Three concentrations of Colchicines, 0.2%, 0.4% and 0.6%, were used to shoot tips of seedling and seeds soaked for tetraploid induction. The cytology, morphological, drought-resistance, fruit quality and storage quality of tetraploid and diploid were studied systematically incomparison.The major results are as following:1, Seeding dropped and seeds soaked: (1) The result of seeding dropped showed that: Different concentration of colchicines all have worked on inducing tetraploid. At the same conditions of others, we used the concentration of 0.4% colchicine for 6d to induce tetraploid melon and brought the best effect, the inducement percentage was 6.67%. The concentration of 0.6% colchicine for 6d brought the better effect, the inducement percentage was 3.33%. And along with boosting of colchicine concentration, the survival plantlet percentage has a reduction trend. (2)The result of seeds soaked showed that: there were tetraploid plantlets under the concentration of 0.4% colchicine , the inducement percentage was 3.33%. The method of seedling dropped was beter than seeds soaked for inducing tetraploid.2, Cytology research showed that: the stomata density of the leaf on the mutated plantlets become less, the guard cells become larger and more chloroplast in stoma cell than what of diploid; the chromosome number of mutated plantlets was 2n=4x=48.3, Compared with the original diploid plant, the tetraploid plant showed that : The leave became thicker, colour of leave and flower became deeper, the leaf index became smaller, the corolla of male flower and female flower become bigger, the length of sepal became shorter and leafstalk ,ovary and stem become shorter and stronger; The size of fruit and seed cavity, the fruit index become smaller, but the flesh thickness and the size of umbilicus have significant increase; the seed width and thousand-grain weight have significant increase and lower fertility.4, The drought-resistance of tetraploid plant was stronger than diploid. Germination stress index, PHSI, SDSI, DMSI, chlorophyll relative content, soluble sugar relative content and proline relative content of tetraploid were higher than diploid, but the random water content, WSD and MDA relative content were lower than diploid.5, There were significant differences in quality of fruits between tetraploid and diploid. The content of central soluble solids, edge soluble solids, Vc, soluble sugar, soluble protein and titrating acid of tetraploid fruit were higher than diploid. The respiratory metabolism of tetraploid fruit was slower than diploid, so the storage quality of tetraploid fruit was greater than diploid.