Gebauer Renate L E, Strain Boyd R, Reynolds James F
Department of Botany, Duke University, Durham, NC 27708-0840, USA, , , , , , US.
Oecologia. 1997 Dec;113(1):29-36. doi: 10.1007/s004420050350.
We examined the extent to which carbon investment into secondary compounds in loblolly pine (Pinus taeda L.) is changed by the interactive effect of elevated CO and N availability and whether differences among treatments are the result of size-dependent changes. Seedlings were grown for 138 days at two CO partial pressures (35 and 70 Pa CO) and four N solution concentrations (0.5, 1.5, 3.5, and 6.5 mmol l NONH) and concentrations of total phenolics and condensed tannins were determined four times during plant development in primary and fascicular needles, stems and lateral and tap roots. Concentrations of total phenolics in lateral roots and condensed tannins in tap roots were relatively high regardless of treatment. In the smallest seedlings secondary compound concentrations were relatively high and decreased in the initial growth phase. Thereafter condensed tannins accumulated strongly during plant maturation in all plant parts except in lateral roots, where concentrations did not change. Concentrations of total phenolics continued to decrease in lateral roots while they remained constant in all other plant parts. At the final harvest plants grown at elevated CO or low N availability showed increased concentrations of condensed tannins in aboveground parts. The CO effect, however, disappeared when size differences were adjusted for, indicating that CO only indirectly affected concentrations of condensed tannins through accelerating growth. Concentrations of total phenolics increased directly in response to low N availability and elevated CO in primary and fascicular needles and in lateral roots, which is consistent with predictions of the carbon-nutrient balance (CNB) hypothesis. The CNB hypothesis is also supported by the strong positive correlations between soluble sugar and total phenolics and between starch and condensed tannins. The results suggest that predictions of the CNB hypothesis could be improved if developmentally induced changes of secondary compounds were included.
我们研究了在火炬松（Pinus taeda L.）中，二氧化碳浓度升高和氮有效性的交互作用对次生化合物碳投入的影响程度，以及处理间差异是否是由大小依赖性变化导致的。幼苗在两种二氧化碳分压（35和70 Pa CO）和四种氮溶液浓度（0.5、1.5、3.5和6.5 mmol l NONH）下生长138天，并在植物发育过程中对初生针叶、束生针叶、茎、侧根和主根中的总酚和缩合单宁浓度进行了四次测定。无论处理如何，侧根中的总酚浓度和主根中的缩合单宁浓度都相对较高。在最小的幼苗中，次生化合物浓度相对较高，并在初始生长阶段下降。此后，除侧根外，所有植物部位的缩合单宁在植物成熟过程中都强烈积累，而侧根中的浓度没有变化。侧根中的总酚浓度继续下降，而其他所有植物部位的总酚浓度保持不变。在最终收获时，在高二氧化碳浓度或低氮有效性条件下生长的植物地上部分的缩合单宁浓度增加。然而，当对大小差异进行调整后，二氧化碳的影响消失了，这表明二氧化碳只是通过加速生长间接影响缩合单宁的浓度。总酚浓度在初生针叶、束生针叶和侧根中直接响应低氮有效性和高二氧化碳浓度而增加，这与碳-营养平衡（CNB）假说的预测一致。可溶性糖与总酚之间以及淀粉与缩合单宁之间的强正相关也支持了CNB假说。结果表明，如果将次生化合物的发育诱导变化包括在内，CNB假说的预测可能会得到改善。
