Click on “Download PDF” for the PDF version or on the title for the HTML version.


If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

Development of a Low-Cost Root Collar Diameter Measurement System for Pine Seedlings

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Paper number  035003,  2003 ASAE Annual Meeting . (doi: 10.13031/2013.14113) @2003
Authors:   Tony E. Grift
Keywords:   Seedling, Root Collar Diameter, Measurement, Optical

To assess the growth stage of the crop in the field, every year seedling nurseries measure the Root Collar Diameter (RCD) of a large number of seedlings. This is traditionally done manually using a slide micrometer and registration of data on paper, a tedious and error-prone practice. As an alternative, an optical system was developed that measures the RCD of a pine seedling semiautomatically.

As a proof of concept, a system was devised where objects of constant diameter were mounted on the rim of a wheel spinning at a constant speed. The diameters of the objects were measured with optical sensors, producing a maximum error of 2.85 %.

Two realistic versions of a semi-automatic RCD measurement system were developed, 1) a system where the user slides the seedling along an edge and 2) a system where the user places the seedling on a table after which the system measures and stores the RCD at the push of a button. The first version produced errors less than 0.7%, sufficiently accurate, but operator dependent and not very user-friendly. The second version had an accuracy better than 0.2%, virtually independent of operator skill.

The concept of measuring the RCD on-the-fly using an optical method could be used to develop a seedling yield monitor on a seedling harvester (lifter) in the near future, although the transition from laboratory to field conditions will require redesign and intensive testing.

(Download PDF)    (Export to EndNotes)