| The research refers to the physical and mechanical properties, distribution regularity ofgelatinous fiber (G-fiber) cells of11new clones and NL-351clone of Populus deltoides whichwere11-year-old. The paper analyzed and discussed by the mathematical statistics in order toseek the wood quality characters and variation. The results show as follow:(1).The average basic density and air-dried of12clones was0.358g·cm-3and0.439g·cm-3.The maximum density of4-45clone was0.400g·cm-3and0.496g·cm-3, which was7.24%and8.68%higher than NL-351clone. While the variance coefficient of4-45clone was smaller thanNL-351clone. The difference of density among trees was significant at a=0.01level.(2).The tangential, radial and volume shrinkage from green wood to oven-dry rate were8.8%,3.38%and12.38%respectively. The tangential, radial and volume shrinkage from greenwood to air-dry rate were5.4%,1.9%and7.4%respectively. The ratio of tangential shrinkageto radial shrinkage at oven-dried condition and air-dried condition were2.6and2.9, which wasrelatively large. The shrinkage from green wood to oven-dry rate of4-45clone and10-34clonewere higher than NL-351. The shrinkage from green wood to air-dry rate of7-45clone and4-6clone were higher than NL-351.The shrinkage from green wood to air-dry of other clones wereclose to NL-351. Analyzing the variance coefficient within the clones, we found that7-45clonehad big difference within the clone. The tangential shrinkage from green wood to oven-dry rateamong12clones were slightly significant at0.05level, The radial and volume shrinkage fromgreen wood to oven-dry rate and the radial shrinkage from green wood to air-dry rate wereslightly significant at0.01level, while there had no significant difference including thetangential, volume shrinkage from green wood to air-dry rate and the ratio of tangentialshrinkage to radial shrinkage.(3).The compressive strength parallel to grain, bending strength, MOE and toughness of12clones were24.14MPa,72.03MPa,7002Mpa and75.75kJ/m2. The maximum compressivestrength parallel to grain of12clones was the10-34clone, followed by the4-45,4-6,7-40clone;The maximum bending strength12clones was the4-45clone, followed by the10-34,7-40,4-6clone; The maximum MOE of12clones was the7-40clone, followed by the4-45,10-34,4-50,7-38,2-2,4-6clone; Overall, three mechanical properties of the4-6,4-45,7-40,10-34clonewere higher than NL-351; the toughness of4-50was higher than NL-351. Among the12clones,the compressive strength parallel to grain andMOE had significant difference at0.05level,bending strength and toughness had significant difference at0.01level.(4).The density and shrinkage had less significant correlation, however the density hadpositive correlation with the compressive strength parallel to grain, bending strength, MOE andtoughness. According to the cluster analysis of the physical and mechanical properties,12 clones were divided into four categories:1-20,7-45;2-2,4-6,4-50,7-38,8-9and NL-351;4-45,7-40and10-34;7-53. According to the comprehensive strength value and the qualitical effection ofthe wood,12clones were classified as low comprehensive strength and high quality. It could beapplied to packaging and decoration materials. The physical and mechanical properties of the4-45,7-40,10-34clone was better than other clones, while the compressive strength parallel tograin, bending strength and MOE of3clones were in line with the general requirements ofwooden construction, so they could be used as wooden construction.(5).The distribution types of gelatinous fiber (G-fiber) in Populus deltoides were diffusein-aggregates (or islands) and tangential banded. The average G-fiber tissue properties of12clones was11.73%. The maximum G-fiber tissue properties of4-45clone was19.31%, thesecond tissue properties of the1-20,4-6clone were18.83%and15.54%,The minimum G-fibertissue properties of10-34clone was5.16%.The gelatinous fiber tissue proportion of10-34and7-45were less than NL-351From pith to bark, the gelatinous fiber cells of12clones generallyappeared reduced trend.The G-fiber tissue proportion of the first four rings was significantlyhigher than others. The G-fiber tissue proportion of some individual rings near bark alsoincreased.Among the12clones, the G-fiber had significant difference at0.01level.According to the results of the physical and mechanical properties and the distributionregularity of G-fiber, the overall physical and mechanical properties of the4-45,7-40,10-34clone was better than other8clones and NL-351. The G-fiber tissue properties of the7-45and10-34was higher than NL-351. To sum up, the comprehensive property of10-34was betterthan other10clones and NL-351, and we could choose the10-34clone as the superior clone tocultivate. |
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