Acacia mangium Willd. is an economic species for pulp and paper industry. The growth of the young tetraploid A.mangium trees was more superior than that of the diploid trees. The present study deals with the effects o...Acacia mangium Willd. is an economic species for pulp and paper industry. The growth of the young tetraploid A.mangium trees was more superior than that of the diploid trees. The present study deals with the effects of age and multiploidy on fiber characteristics in tetraploid and diploid species. They were compared and analysed using Franklin’s method with hydrogen peroxide and glacial acetic acid treatment, the data were analysed from micromeasurements. With age increment, the fiber length in the diploid trees increased significantly( p<0 01). Similarly, the fiber length measured in the same year also showed decrease from bottom upward along with the growth of the shoot height. The tetraploid wood fibers were also compared and analysed with the diploid fibers. In the 1\|year\|old shoots, the tetraploid fiber was significantly longer than the diploid’s ( p<0 01 ), Whereas the Cw/Cav (ratio of the thickness of cell wall and the cavity of cell)of the tetraploid fibers was significantly smaller than that of the diploid’s( p<0 01 ). Moreover, regardless of the age, in the main leaf veins the tetraploid fiber length was, similar to that in the wood, sinificantly longer than that of the diploid’s, and the Cw/Cav was also significantly smaller. It is thus suggested that the fiber characteristics measured in the main leaf veins, which is a much easy and safe procedure, could possibly be expected to obtain the same results in adult wood.展开更多
文摘采用4点加载方式对马占相思木材试件进行短时间(420 min)弯曲蠕变实验,获取马占相思木材弯曲蠕变特性曲线,根据弯曲蠕变特性曲线确定马占相思木材的粘弹性元件常数。同时研究马占相思木材在强度极限内,应力水平与木材蠕变的关系。实验结果表明:当弯曲应力为σb20%时,J0(瞬间弹性柔量)为6.954×10-7 cm2/N、η0(粘性系数)为1 111.111×10-7 min N/cm2、ΣJi(延迟弹性柔量)为0.572×10-7 cm2/N;当弯曲应力为σb30%时,J0为7.939×10-7 cm2/N、η0为267.857×10-7 min N/cm2、ΣJi为1.441×10-7 cm2/N;当弯曲应力为σb40%时,J0为6.540×10-7 cm2/N、η0为326.087×10-7 min N/cm2、ΣJi为2.108×10-7 cm2/N。随着弯曲应力的增加,瞬间弹性柔量J0有波动,但幅度不大;延迟弹性柔量ΣJi则随着应力的增加而增加。在较高应力水平下,粘性系数η0具有较小值,而延迟弹性柔量ΣJi则具有较大值,说明马占相思木材抗蠕变能力较差,宜在低应力下工作。
文摘Acacia mangium Willd. is an economic species for pulp and paper industry. The growth of the young tetraploid A.mangium trees was more superior than that of the diploid trees. The present study deals with the effects of age and multiploidy on fiber characteristics in tetraploid and diploid species. They were compared and analysed using Franklin’s method with hydrogen peroxide and glacial acetic acid treatment, the data were analysed from micromeasurements. With age increment, the fiber length in the diploid trees increased significantly( p<0 01). Similarly, the fiber length measured in the same year also showed decrease from bottom upward along with the growth of the shoot height. The tetraploid wood fibers were also compared and analysed with the diploid fibers. In the 1\|year\|old shoots, the tetraploid fiber was significantly longer than the diploid’s ( p<0 01 ), Whereas the Cw/Cav (ratio of the thickness of cell wall and the cavity of cell)of the tetraploid fibers was significantly smaller than that of the diploid’s( p<0 01 ). Moreover, regardless of the age, in the main leaf veins the tetraploid fiber length was, similar to that in the wood, sinificantly longer than that of the diploid’s, and the Cw/Cav was also significantly smaller. It is thus suggested that the fiber characteristics measured in the main leaf veins, which is a much easy and safe procedure, could possibly be expected to obtain the same results in adult wood.
