Am J Bot. 1997 Dec;84(12):1707.
The carbon isotopic compositions of leaves and stems of woody legumes growing in coastal mediterranean and inland desert sites in California were compared. The overall goal was to determine what factors were most associated with the carbon isotope composition of photosynthetic stems in these habitats. The carbon isotope signature (d13C) of photosynthetic stems was less negative than that of leaves on the same plants by an average of 1.51 ± 0.42 ;pp. The d13C of bark (cortical chlorenchyma and epidermis) was more negative than that of wood (vascular tissue and pith) from the same plant for all species studied on all dates. Desert woody legumes had a higher d13C (less negative) and a lower intercellular CO2 concentration (Ci ) (for both photosynthetic tissues) than that of woody legumes from mediterranean climate sites. Differences in the d13C of stems among sites could be entirely accounted for by differences among site air temperatures. Thus, the d13C composition of stems did not indicate a difference in whole-plant integrated water use efficiency (WUE) among sites. In contrast, stems on all plants had a lower stem Ci and a higher d13C than leaves on the same plant, indicating that photosynthetic stems improve long-term, whole-plant water use efficiency in a diversity of species.
对生长在加利福尼亚沿海地中海和内陆沙漠地区的木本豆科植物的叶片和茎的碳同位素组成进行了比较。总体目标是确定哪些因素与这些生境中光合作用茎的碳同位素组成最相关。与同一植物的叶片相比，光合作用茎的碳同位素特征（d13C）平均低 1.51 ± 0.42；pp。在所有研究的日期，所有研究物种的树皮（皮层薄壁组织和表皮）的 d13C 比同一植物的木材（维管束组织和髓）更负。与来自地中海气候地点的木本豆科植物相比，沙漠木本豆科植物的 d13C（负值更小）和细胞间 CO2 浓度（Ci）（对所有光合作用组织而言）更低。不同地点茎的 d13C 差异可以完全用地点空气温度的差异来解释。因此，茎的 d13C 组成并不能表明不同地点植物整体水分利用效率（WUE）的差异。相比之下，所有植物的茎的 Ci 较低，d13C 较高，与同一植物的叶片相比，表明光合作用茎提高了多种物种的长期整体水分利用效率。
