Study On Wood Property And Anatomical Structure Of Red-heart And Normal Chinese Fir In Different Forest Ages

In this study,taking two different types of Chinese fir(red-hart and normal Chinese fir)plantation of different ages(15a and 30a)in Beijianghe Forest Farm in Rongshui Guangxi as the research objects.maesuring its different sites(heartwood,mid-wood and sapwood)wood property such as moisture content,basic density,annual ring width,late wood percentage,tracheid traits,tissue proportion,wood color etc,and obvived the microstructure characteristics.By comparing the differences in wood property and microstructure characteristic of the two types of Chinese fir,it provides a theoretical basis for genetic breeding of red-hart Chinese fir.The main research was showed below.(1)From the heartwood to sapwood,the moisture content and basic density of the two types of Chinese fir in different ages showed a gradual increase trend,and the radial variation had a significant or extremely significant difference;The difference in basic density of each part between the two types of Chinese fir was showed as: red-heart Chinese fir>normal Chinese fir,and there was a extremely s ignificant difference in the mid-wood and a significant difference in the sapwood.(2)From the heartwood to sapwood,the ring width was gradually decreased,and reached a extremely significant difference level;Variation law of latewood percentage of red-heart Chinese fir was:heartwood<mid-wood<sapwood,normal Chinese fir was: mid-wood<heartwood<sapwood,no significant difference in radial variation of late wood percentage.The difference of annual ring width between two types of Chinese fir was: normal Chinese fir>red-heart Chinese fir,and very significant difference in the heartwood and the sapwood.The latewood percentage of red-heart Chinese fir was higher than that of normal Chinese fir,and had significant difference in the sapwood.(3)The tracheid length of red-heart and normal Chinese fir in different forest ages showed a gradually increasing trend from the heartwood to sapwood.The early-wood tracheid width,cavity diameter,and width-cavity diameter ratio of each part were greater than the late-wood,and the early-wood double-wall thickness,tracheid wall thickness-diameter ratio were less than the late-wood.The above differences were reached a significant or extremely significant level.The two types of 15 a Chinese fir tracheid traits had no difference.While the tracheid width,cavity diameter,and width-cavity diameter ratio between the two types of 30 a Chinese fir were shown as: normal Chinese fir>red-heart Chinese fir;tracheid length-width,wall thickness-diameter ratio were showed as: red-heart Chinese fir > normal Chinese fir,and reached a significant or extremely significant level.(4)From heartwood to sapwood,the parenchyma proportion、xylem ray proportion of the two type of Chinese fir gradually decreased,while the tracheid proportion gradually increased.The parenchyma proportion、xylem ray proportion of the latewood was higher than the earlywood of the two typs of Chinese fir,and each tissues proportion of red-heard Chinese fir was higher than normal Chinese fir in each parts,while the tracheid proportion showed the opposite pattern,Parenchyma proportion was showed the significant difference between earlywood and latewood of red-heard Chinese fir in the heartwood and mid-wood.(5)The L~* at the sapwood of two types of Chinese fir at different forest ages was extremely significantly greater than that at the heartwood and mid-wood.The radial variation of a~* and b~* were basically the same,from heartwood to siapwood showed a decreasing trend.The L~*,a~*,b~*values in each part between of the two types of Chinese fir were expressed as: red-heart Chinese fir>normal Chinese fir.Variance analys is results showed: There were significant or extremely s ignificant differences in the radial variation of L~* and a~*.L~* in the sapwood between 15 a two types of Chinese fir,and a~*,b~* in the heartwood and b~*in the mid-wood of 30 a reached a significant difference,and there was no significant difference in the others.(6)Two types of Chinese fir cell structure was composed of parenchyma cell,tracheid and xylem ray.The difference between early and late wood was obvious.Early wood tracheid was large and thin,while late tracheid was small and thick;parenchyma cell contained resin;The xylem ray was consisted of ray parenchyma,and had inclusions,1～2 cells wide,and 6 cells high on average.Both had taxodioid pit border-field pit and araucaria-type B.There was no obvious difference in the anatomical composition of the two types of Chinese fir.(7)Correlation analys is of two types of 30 a Chinese fir wood property: The annual ring width was extremly significantly negatively correlated or significantly negatively with moisture content,basic density,tracheid length and width.Most tracheid traits had significant or extremely significant correlation.In red-heart Chinese fir,L~* was significantly negatively correlated with a~*,and extremely significantly negatively correlated with b~*,no such difference in normal Chinese fir.