Farm Forestry New ZealandAssessing heartwood in E. bosistoana cores from NIR hyperimages
By Clemens Altaner, July 2021.
Download SWP-T124 (pdf)
Executive summary
Assessing heartwood quality with current technology in a research context is resource intensive and not feasible in a commercial setting. NIR imaging has the potential to remotely assess heartwood quality almost instantaneously, opening the door for developing quality control of heartwood (e.g. for natural durability) through breeding and grading.
This pilot study on 175 E. bosistoana cores indicated that NIR imaging can be used to a) identify heartwood and sapwood on a wood surface and b) assess heartwood quality. A descriptive model was able to reliably identify heartwood and sapwood in the E. bosistoana stem cores. The heartwood extractive content was predicted with a RMSE of less than 3%. Considering a heartwood extractive content range from 0 to over 25%, this is a usable outcome. However, the findings should be validated through direct measurements.
A by-product of NIR imaging is the information of the spatial variation of heartwood quality in a sample. Spatial variation in heartwood quality is a topic which has not attracted much attention in the past due to the lack of a suitable analytical technique, but a homogeneous spatial distribution of heartwood extractives is critical for a well performing naturally durable product.
In the first instance NIR imaging should be usable directly for NZDFI’s phenotyping efforts of heartwood. However, the technology appears to have great potential to be used for timber grading in respect to natural durability. Developing a grading method and standard for natural durability would greatly increase the consistency and consumer acceptance of the product.
There are clear but unexplored routes to improve the accuracy of this technology in future, which were outside the scope of this work.
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