However, we used the same root biomass samples for both approaches, and the 14C age of individual roots was still greater as their chronological age (Supplementary Data 1).
Radiocarbon (14C) values of ground fine-root biomass samples from the different forest types were analyzed as follows.
The mean C age was calculated for the 14C values of the fine-root biomass samples, considering the distribution of the oldest and the youngest calibrated dates from both programs.
Yet, according to Mokany et al. [20], sampling to what may be deemed an insufficient soil depth to capture the majority of the roots, while not sampling the root collar or fine roots, as well as sampling with inadequate replication, are a few of the methodological pitfalls associated with sampling root biomass, and can lead to underestimation.
Yet, according to Mokany et al. [ 20], sampling to what may be deemed an insufficient soil depth to capture the majority of the roots, while not sampling the root collar or fine roots, as well as sampling with inadequate replication, are a few of the methodological pitfalls associated with sampling root biomass, and can lead to underestimation.
Assuming a compromise between FA production and hairy root biomass, it was determined that sampling times 4 and 5 gave the most useful FA yields.
However, the optimal PUFA productivity in this hairy root system was always associated with the highest biomass density during the culture period; therefore, assuming a compromise between FA production and hairy root biomass, it was determined that sampling times 4-5 gave the most beneficial FA yields.
Difficulties associated with sampling below-ground root biomass accurately often leads to allometric equations that potentially under-estimate below-ground biomass.
Matthews [8] measured root biomass of two S. viminalis varieties, sampling five single plants from two sites, four Bowles hybrid from one site and a single Gigantea variety from the second site.
As fine roots are an important component of the below ground biomass [7,15,40] and fine root volumes were not accurately assessed using the methods described in section 2.4, an in-depth sampling of fine root biomass was carried out to coincide with the destructive harvest during the second rotation in July 2013 at both field sites.
