| Tree stems of Phoebe hui form Ya'an of Sichuan province?Phoebe bournei from Nanping of Fujian province and Phoebe sheareri from Wuhu of Anhui province were selected as research material respectively.The tree age were between 30a and 40a.Macro and micro structure characteristics of three kinds of woods were observed by handheld microscope and optical microscope,and the ultrastructural characteristics was observed by scanning electron microscope.Based on North-South direction,measure the width of each growth ring was measuring by vernier caliper with a 2a gradient.The structural parameters of each gradient from the heart to the bark were measured by wood image analysis software,including the length of vessel,tangential diameter of pore,density of pore,fiber length,fiber width and fiber lumen-diameter,the height and width of wood ray,and the fiber double wall thickness,fiber length-width ratio and fiber wall cavity ratio were evaluated.The variation curves of various parameters are drawn by Excel.The variation curves of various parameters were plotted by Excel,and the regularity was analyzed.The correlation between tree age and various cell parameters was analyzed with SPSS software.The physical and mechanical properties of wood were tested by international standards,including the density and dry shrinkage of wood,the compressive strength of the grain and the bending strength.The result showed:(1)On the macro structural features,three kinds of Phoebe woods were different.The gloss of Phoebe sheareri was weaker than Phoebe hui and Phoebe bournei.On new cut noodles,Phoebe bournei smelled sweet and fragrant,Phoebe hui smelled irritant with a myrrh fragrance,and Phoebe sheareri had no odor.Phoebe hui and Phoebe sheareri belonged to diffuse-porous wood,Phoebe bournei was diffuse porous to semi-diffuse porous wood.(2)In the micro structural features,Phoebe hui,Phoebe bournei and Phoebe sheareri were similar,mainly in the hole was round or oval,partly with polygon.Vessel perforation was simple perforation.The pit between vessels was alternate pitting.Having septate wood fiber.The main shape of longitudinal parenchyma was vasicentric and scanty paratracheal,a few apotracheal parenchyma;Ray parenchyma was heteromorphism III or II.Three kinds of woods had little difference in the characteristics of the four basic tissues,only slightly different on the characteristic parameters.The oil cells often appeared in the axial parenchyma of Phoebe hui and Phoebe bournei in the axial parenchyma,but the oil cells of the Phoebe sheareri were few.(3)Under electron microscope,there were square calcium crystals in three kinds of woods in xylem ray cells.Phoebe bournei had a lot of gum substances in axial parenchyma cells and xylem ray cells.There were a lot of gum compounds in wood ray cells of Phoebe hui,but only a little gum compounds exist in Phoebe sheareri ray cells.(4)Fiber length and width belonged to middle grade of three kinds of woods.The ratio of length to width was 44.29,55.95 and 65.34,respectively,and the wall lumen ratio was 0.61,0.74,and 0.54,respectively.There were all good fiber material,the Phoebe sheareri best.In ray form,three of them belong to low and narrow type,in which Phoebe hui and Phoebe sheareri were very similar,and both lower than phoebe bournei in ray height.In the morphology of vessels,length and size of the three are all medium,and the length of vessel were the same,tangential diameter of pore of phoebe bournei was the largest,Phoebe sheareri was the smallest.The density of hole were 19,16 and 22respectively,and the three are slightly less.(5)There were differences in the law variation of the width of growth ring of Phoebe hui,phoebe bournei and Phoebe sheareri.The growth rate of phoebe bournei was fast and the width of growth ring could reach 6.05mm.The production of Phoebe Phoebe could be considered as fast-growing wood.There radial variation of fiber length showed almost linear growth.The pattern of fiber width variation was different.Because the linear growth of fiber length and the steady state of fiber width,length to width ratio presents the variation pattern similar to the fiber length,which was fluctuating upward from the pith to outside.The radial variation of wall to lumen ratio were different.The overall fluctuation of the width of wood ray was stable,length of vessel,diameter of pore and the density of pore were the same,length of vessel and tangential diameter of pore were fluctuating upward,and the overall density of the tube hole was fluctuating downward.(6)At the P<0.01 level,tree age had a significant positive correlation with fiber length,fiber length to width ratio,length of vessel,tangential diameter of pore,and the growth ring width,number of pores,the height and width of wood ray,and so on,according to the difference of tree species.(7)The basic density were 0.42g/cm~3,0.48 g/cm~3and 0.5 g/cm~3of Phoebe hui and phoebe bournei and Phoebe sheareri,respectively.there air dry density were 0.57g/cm~3,0.64g/cm~3and 0.67 g/cm~3respectively,and the total-dry density were 0.47g/cm3,0.54g/cm3 and 0.57 g/cm3 respectively.Three kinds of wood air dry density were moderate,and Phoebe sheareri density maximum,the minimum density of Phoebe hui.The tangential and radial shrinkage and contrast shrinkag were small of Phoebe hui.Middle for phoebe bournei and Phoebe sheareri.It showed that the three kinds of woods had good dimensional stability and were not easy to crack and warp when wood was dehydrated.(8)The comprehensive strength of Phoebe hui and Phoebe bournei and Phoebe sheareri were 119.19Mpa,172.11Mpa,150.79Mpa,respectively.Both of Phoebe bournei and Phoebe sheareri belong to medium,and Phoebe hui was low. |
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