Oberhuber Walter, Swidrak Irene, Pirkebner Daniela, Gruber Andreas
Leopold-Franzens-University of Innsbruck, Institute of Botany, Sternwartestrasse 15, A-6020 Innsbruck, Austria.
Can J For Res. 2011 Aug;41(8):1590-1597. doi: 10.1139/x11-085.
Wood formation requires a continuous supply of carbohydrates for structural growth and metabolism. In the montane belt of the central Austrian Alps we monitored the temporal dynamics of xylem growth and non-structural carbohydrates (NSC) in stem sapwood of Pinus sylvestris L. during the growing season 2009, which was characterized by exceptional soil dryness within the study area. Soil water content dropped below 10 % at the time of maximum xylem growth end of May. Histological analyses have been used to describe cambial activity and xylem growth. Determination of NSC was performed using specific enzymatic assays revealing that total NSC ranged from 0.8 to 1.7 % dry matter throughout the year. Significant variations (P < 0.05) of the size of the NSC pool were observed during the growing season. Starch showed persistent abundance throughout the year reaching a maximum shortly before onset of late wood formation in mid-July. Seasonal dynamics of NSC and xylem growth suggest that (i) high sink activity occurred at start of the growing season in spring and during late wood formation in summer and (ii) there was no particular shortage in NSC, which caused P. sylvestris to draw upon stem reserves more heavily during drought in 2009.
木材形成需要持续供应碳水化合物以支持结构生长和新陈代谢。在奥地利中部阿尔卑斯山的山区地带，我们监测了2009年生长季期间欧洲赤松茎边材木质部生长和非结构性碳水化合物（NSC）的时间动态，该生长季的特点是研究区域内土壤异常干燥。5月底木质部生长达到最大值时，土壤含水量降至10%以下。组织学分析已用于描述形成层活动和木质部生长。使用特定的酶促测定法对NSC进行了测定，结果显示全年总NSC含量在干物质的0.8%至1.7%之间。在生长季期间观察到NSC库大小存在显著变化（P < 0.05）。淀粉全年持续丰富，在7月中旬晚材形成开始前不久达到最大值。NSC和木质部生长的季节动态表明：（i）春季生长季开始时和夏季晚材形成期间出现了高汇活性；（ii）NSC没有特别短缺，这导致欧洲赤松在2009年干旱期间没有更多地动用茎储备。
