氮素对两种杨树木材品质的影响.docVIP

 氮素对两种杨树木材品质的影响# 5 10 15 20 25 30 35 40 45  摘要：氮素是林木生长所需的大量营养元素，直接影响着林木的生长和木材品质。杨树作为 我国重要的绿化和速生丰产林树种，也是造纸工业的重要原材料，在我国北方地区大量种植。 尽管施肥在杨树速生丰产林的培育中已成为一项重要的栽培措施，然而，施加氮肥究竟怎样 影响杨树木材的品质还不清楚。因此，本研究以氮素不足（0 mM）、氮素适中（5 mM）和 氮素充足（10 mM）处理两种杨树（群众杨和 84K 杨）幼苗，分析测定林木木质部细胞壁 的结构、纤维和导管的形态特征以及木质素含量等，评价氮肥对杨树木材品质的影响。研究 发现：（1）施加氮素影响杨树木质部显微特性。群众杨在扫描电镜下次生木质部纤维细胞 壁内清晰可见纤维素沉积层，而 84K 杨的次生木质部纤维细胞壁中没有发现类似结构。氮 素的施加改变了杨树木质部纤维和导管的特征。随着氮素浓度的提高，杨树纤维和导管的长 度均显著降低，而其宽度显著增加。（2）氮素的施加对杨树木材木质素的合成有重要影响。 随着氮素浓度的升高，两种杨树木材部分木质素含量均呈现下降趋势。这些结果表明，尽管 氮肥能增加木材产量，但可能对木材的最终用途产生深远影响。 关键词：人工林培育；氮肥；木材品质；木质素；杨树 中图分类号：S792.11 Impacts of Nitrogen Fertilization on Wood Properties of Two Populus Species Li Mengchun1, Luo Zhibin2 (1. College of Life Sciences, Northwest Agriculture and Forestry University, Shaanxi YangLing 712100; 2. Key Laboratory of Environment and Ecology in Western China of Ministry of Education, College of Forestry, Northwest Agriculture and Forestry University, Shaanxi YangLing 712100) Abstract: Nitrogen (N) is an essential macronutrient which can impact wood productivities and properties. However, little is known about how N may affect wood properties of poplar species. To address the influences of N fertilization on wood properties of woody plants, saplings of two poplar species (Populus popularis and Populus alba × P. glandulosa) were exposed to 0, 5 and 10 mM NH4NO3 for 7 weeks and subsequently, wood properties were analyzed. Vessel and fiber characteristics were affected by N fertilization. The samples from the two species treated with 10 mM NH4NO3 contained significantly shorter fibers and vessels than the lower N treatments. Vessel and fiber widths were larger under higher N supply. Thicker fiber cell walls were formed under higher N levels. High N availability increased cellulose deposition in xylem fiber cell walls which is mainly due to the formation of a G-layer in P. popularis. Lignin concentrations were tended to decline after N fertilization in both species. These results indicate that N