Durall D M, Marshall J D, Jones Melanje D, Crawford R, Trappe J M
Department of Forest Science, Oregon State University, Corvallis, Oregon 97331, USA.
New Phytol. 1994 Aug;127(4):719-724. doi: 10.1111/j.1469-8137.1994.tb02975.x.
Seedlings of Pinus Ponderosa Dougl, ex. Laws were grown in root observation containers. They were inoculated with either Hebeloma crustuliniforme (Bull.) Quel. or Laccaria bicolor (Maire) Orton or left uninoculated (control). Oil a monthly basis starting at the eighth month of a 12-month growing period, roots (mycorrhizal root tips from inoculated plants, non-mycorrhizal from control plants) were traced onto acetate sheets. Each root tip was classified as light, 'intermediate' or 'dark' in colour. Roots initiated between months eight and nine were monitored for the next 90 d. All root tips progressed from light-brown to dark-brown to black for all three treatments. Hebeloma crustuliniforme, and to a lesser extent L. bicolor, retarded this progression relative to the control. At the end of 12 months, seedlings were labelled with CO to determine the effects of ectomycorrhizal inoculation on carbon supply to roots of the different morphological categories. The amount of C in 'light'L. bicolor and H. crustuliniforme mycorrhizas was 2.3 and 1.8 times greater, respectively, than that in 'light' control root tips. The amount of C in mycorrhizas of the inoculated treatments and, to a lesser extent, roots of the control seedlings decreased as they progressed from 'light' to 'dark'. It is concluded that pondersa pine seedlings continue to allocate photosynthate to morphologically older roots, perhaps to meet maintenance requirements or to supply carbon for growth and metabolism of extra-matrical hyphae. Such allocation may enhance root longevity, which would have an important influence on tree, forest and soil carbon budgets.
西黄松（Pinus ponderosa Dougl, ex. Laws）幼苗种植于根系观察容器中。将其接种卷边桩菇（Hebeloma crustuliniforme (Bull.) Quel.）或双色蜡蘑（Laccaria bicolor (Maire) Orton），或不接种作为对照。在为期12个月的生长周期的第8个月开始，每月一次，将根系（接种植物的菌根根尖，对照植物的非菌根根尖）描绘在醋酸纤维纸上。每个根尖按颜色分为浅色、“中间色”或“深色”。对在第8至9个月间生出的根系在接下来的90天进行监测。对于所有三种处理，所有根尖均从浅棕色变为深棕色再变为黑色。卷边桩菇，以及在较小程度上的双色蜡蘑，相对于对照延缓了这种变化进程。在12个月结束时，用¹⁴CO₂标记幼苗，以确定外生菌根接种对不同形态类别的根系碳供应的影响。双色蜡蘑和卷边桩菇“浅色”菌根中的¹⁴C量分别比“浅色”对照根尖中的¹⁴C量高2.3倍和1.8倍。接种处理的菌根以及在较小程度上对照幼苗的根系中的¹⁴C量随着它们从“浅色”变为“深色”而减少。得出的结论是，西黄松幼苗继续将光合产物分配到形态上较老的根系，可能是为了满足维持需求或为根外菌丝的生长和代谢提供碳。这种分配可能会延长根系寿命，这将对树木、森林和土壤碳预算产生重要影响。
