| Populus, a fast growing tree, solves the problem of wood shortages in many parts of the world. In this study, we adopted Aigeiros section as our research materials for their maximum economic values, then to select some new poplar varieties cultivated suitably in Hubei Province, which have characters of fast-growing, narrow crown and strong tolerance.2004～2005, artificial control indoor hydroponics hybridization was performed using5superior poplar clones of Aigeiros section, and gained1271clones. After seedling selection, some clones whose seeding growth increment was higher than parental clones’ were selected in spring of2007and2008respectively, as well as to create2regional test forest. Up to now, they were5a,4a forest respectively. From2007, we started to investigate all clones in autumn when they stopped growing. The contents of investigation cover tree height, diameter at breast height(DBH), clear bole height, crown width, branching angle and the harm condition of Rust Disease, Poplar Canker Disease, Longicom Beetles under natural condition. From analysis, the main contents and conclusions are summarized as follows:(1) The parasitic rate of Longicom Beetles in5a forest was0.74%, and in4a forest was14.8%. The5a forest and4a forest did not happen Canker Disease, and the rust infection index in2forest was almost equal. In terms of rust infection index, the pest resistance heritability of5a and4a forest was0.13and0.3respectively. And the high variation ability make it possible to breed some new clones with strong tolerance. Among them, poplar clone LH04-17suffered the lowest rust infection index, so LH04-17suitable for new poplar varieties which has strong tolerance.(2)From tree traits, the heritability of breast-height form factor changed from0.30to0.37, the heritability of crown DBH ratio was0.23, the heritability of branching angle was0.25, the heritability of tree traits was low, and has high variation ability, affected by external factors greatly. The breast height form factor and crown DBH ratio of5a poplar clones were stable compared to4a forest. Among2forest, the lowest crown DBH ratio was found in clone LH04-13, so LH04-13suitable for new poplar varieties which has narrow crown.(3)According to the breeding aim, it selected9super poplar clones in5a forest: LH04-13、LH04-8、LH04-17、LH04-24、♀L04-17、LH04-21、LH04-15、LH04-1、 LH05-s4, it selected10super poplar clones in4a forest:SN04-19、NH05-20、LH04-13、 LH04-8、LH04-17、SN05-10、LH04-15、LH04-18、LH05-275、LH05-228.After young forest selection, in5a forest were selected with36%selection rate, the height average reached18.4m, genetic gain in height changed from6.2%to10.3%, the diameter at breast height average reached19.7cm, genetic gain in DBH changed from16.9%to23.5%, the volume average reached0.2089m3, genetic gain in volume changed from40.0%to58.2%. In4a forest were selected with26%selection rate, the height average reached15.0m, genetic gain in height changed froml.5%to7.8%, the diameter at breast height average reached14.2cm, genetic gain in DBH changed from11.6%to15.1%, the volume average reached0.0927m3, genetic gain in volume changed from26.0%to40.7%.(4)Result from stem analysis of3trees indicates that the mean annual increment of DBH of6year old LH04-8, LH04-13and LH04-17were3.3cm,3.2cm,2.9cm, and it showed mean annual increment of height of2.8m,3.0m,2.9m, representing mean annual increment of volume of0.0267m3,0.0283m3and0.0301m3, respectively. Trunk profile diagram showed that3clones had good displays in stem straight, stem fatness, and their mean increment and mean annual increment of diameter at breast height changed relatively greatly, meanwhile mean increment of height was higher than their mean annual increment value in6years, however, the volume showed opposite result. The mean annual increment of height was large in3years, and the mean annual increment of diameter at breast height of4year old reached maximum, so prophase rate increased quickly and breast height form factor had large varied amplitude. After4year, the increment rate is low at stable-period of growth, and the mean increment and mean annual increment of volume increased with age.(5) Populus clones LH04-17and LH04-13had been selected and assessed by Hubei Committee of Tree Species Assessment as good-growth ones in2012, and named new poplar cultivars ’Huashi1’ and ’Huashi2’... |
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