| Phyllostachys edulis cv. pachyloen, which was discovered and reported in 1980s and was given the name formally in 1997, is a new variety of Phyllostachys edulis. The paper mainly describes its genetic characters and breeding technology.The most remarkable phenotypic features of Phyllostachys edulis cv. pachyloen is its very thick culm wall, whose breast-high average thickness is over 2.5cm, which is 1.8 times thicker than that of Phyllostachys edulis. The average rate of culm wall reaches 59.3 percent, which is 2.0 times more than that of Phyllostachys edulis. The average bamboo height in Phyllostachys edulis cv. pachyloen 's populations is 9.86m; its average clear-bole height is 3.50m; its average breast-height girth is 16.55cm, its average culm weight is 12.4kg and the average ratio of culm and leaves is 8:2. Bamboos of Phyllostachys edulis cv. pachyloen in the four natural distributed populations and several introduction groups in different ecological condition have the stable "thick wall" character, which proves that the "thick wall" phenotypic character can be inherited stably. The chromosome number in the tip of Phyllostachys edulis cv. pachyloen is proved to be 2n=48, which shows that it is not polyploid of Phyllostachys edulis (moso bamboo). It is found out by RAPD testing that genetic similarity between Phyllostachys edulis cv. pachyloen and Phyllostachys edulis amounts to 0.9756, while genetic similarity between Phyllostachys edulis cv. pachyloen and Phyllostachys hetarocycla cv. taokiang, Phyllostachys heterocycla and Phyllostachys edulis cv. tubaeformis is 0.9512,0.9268 and 0.8537 respectively, which indicates that Phyllostachys edulis cv. Pachyloen has the closest genetic relationship with Phyllostachys edulis. The result of RAPD molecular genetic test on four natural distributed populations of Phyllostachys edulis cv. pachyloen indicates that these four groups have the same hereditary basis, which provides theoretic basis for heredity and nursing of Phyllostachys edulis cv. pachyloen. Individual RAPD comparison has been carried out in seven different Phyllostachys edulis cv. pachyloen's populations and Phyllostachys edulis's populations, and 9 peculiar marking loci in Phyllostachys edulis cv. pachyloen have been found out. It is proposed that Phyllostachys edulis cv. pachyloen is the sudden genetic variant of one or several genes of Phyllostachys edulis.The paper also discusses the study and test on a series of important germplasmcharacters of Phyllostachys edulis cv. pachyloen from their ages, parts, provenances and introduction places by related national standards. The findings are as follows: the average fiber length of its dry timber is 1.382mm; its average fiber width is 12.20 u m; the ratio of its fiber length and width is 114; its average rate of fibrous tissue is 21.83%; its average density of vascular bundle is 313 per cm2; the basic density of its timber is 0.4893g.cm~3 ; its coefficient of elasticity is 11457.7Mpa ; its bending strength (MOE) is 140.57Mpa; its compression strength parallel to the gain is 58.6Mpa and its shock toughness is 40868.OK.g.m-1. The cool water extraction content, hot water extraction content, content of benzyl alcohol extraction, lignin content, !%NaOH extraction content, cellulose content, and pentosan content are 5.45%, 6.38%, 2.55%, 26.55%, 28.99%, 40.51%, and 26.14% respectively. Its 15 nutrient elements' contents have been tested too, among which contents of Ca, S, Al, Fe are noticeably higher than those in Phyllostachys edulis ,but the contents of N, P, K, Mg, Mn, Cu, Zn, B, SiO2 and crude ash have no noticeable difference with those in Phyllostachys edulis . There exists irregular variability between ages, parts and producing places. All these characters prove that Phyllostachys edulis cv. pachyloen is shoot-producing bamboos of high quality.In the leaf blade of Phyllostachys edulis cv. pachyloen, contents of chlorophyll, β -carotene, nitrate reductase activity, pectic enzyme activity and invertase acitvity are 1.953mg.FW.g-1, 6.5...
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