Sundberg B, Ericsson A, Little C H, Näsholm T, Gref R
Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S-901 83 Umeå, Sweden.
Tree Physiol. 1993 Jun;12(4):347-62. doi: 10.1093/treephys/12.4.347.
Indole-3-acetic acid (IAA), carbohydrates, total nitrogen and amino acids in the cambial region and bark were measured at the top (10-year-old internode) and bottom (1.3 m) of the main stem of 50-year-old Pinus sylvestris L. trees, having different rates and longitudinal gradients of annual ring width formation. The trees were sampled during the most active period of wood production (June 23, July 15) and at the end of this period (August 23). Trees with a small crown and relatively slow growth rate (S-trees) were compared with trees in the same stand that had a large crown and fast growth rate (F-trees) as a result of thinning and fertilization. The effect of bottom pruning fast-growing trees (pruned F-trees) was also investigated. The F-trees had greater wood production than the S-trees at both the stem top and bottom. The difference was larger at the stem bottom, thus the relative decrease in ring width down the stem was steeper in the S-trees. The amount of sucrose and IAA per cm(2) in cambial region tissues was higher in F-trees than in S-trees. However, the differences in annual ring width between treatments and within trees were not reflected in the concentrations (expressed per gram fresh weight) of these substances, measured either in differentiating xylem, the cambium plus phloem, or in the cambial region as a whole. The concentrations of total nitrogen and amino acids were slightly higher in the F-trees than in the S-trees. Pruning the F-trees reduced wood production, particularly at the stem bottom, inhibited the springtime increase in starch, and decreased the amounts of sucrose and IAA per cm(2) in the cambial region. However, it was evident that the concentrations of sucrose, IAA, amino acid and nitrogen in the cambial region were not related to ring width. During June and July, the concentrations of these substances were generally higher at the stem bottom in the pruned F-trees than in the F-trees. The results provide evidence that it is the activity of the cambium rather than the availability of carbohydrates that determines the allocation of wood production along the tree stem. The results also indicate that tracheid production is not directly related to the IAA concentration in the cambial region.
对50年生欧洲赤松主干顶部（10年生节间）和底部（1.3米处）形成层区域和树皮中的吲哚 - 3 - 乙酸（IAA）、碳水化合物、总氮和氨基酸进行了测量，这些树木具有不同的年轮宽度形成速率和纵向梯度。在木材生产最活跃时期（6月23日、7月15日）以及该时期结束时（8月23日）对树木进行采样。将树冠较小且生长速率相对较慢的树木（S型树）与同林分中因间伐和施肥而树冠较大且生长速率较快的树木（F型树）进行比较。还研究了对快速生长树木进行底部修剪（修剪后的F型树）的效果。F型树在树干顶部和底部的木材产量均高于S型树。在树干底部差异更大，因此S型树中沿树干向下的年轮宽度相对减少更陡峭。形成层区域组织中每平方厘米的蔗糖和IAA含量，F型树高于S型树。然而，处理之间以及树木内部年轮宽度的差异并未体现在这些物质在分化木质部、形成层加韧皮部或整个形成层区域中（以每克鲜重表示）的浓度上。F型树中总氮和氨基酸的浓度略高于S型树。对F型树进行修剪会降低木材产量，尤其是在树干底部，抑制春季淀粉增加，并减少形成层区域每平方厘米的蔗糖和IAA含量。然而，很明显形成层区域中蔗糖、IAA、氨基酸和氮的浓度与年轮宽度无关。在6月和7月期间，修剪后的F型树树干底部这些物质的浓度通常高于F型树。结果表明，决定沿树干木材产量分配的是形成层的活性而非碳水化合物可用性。结果还表明，管胞产生与形成层区域中的IAA浓度没有直接关系。
