Manual Onion Grading Equipment for Research and Commercial Applications in Developing Countries

Abstract

Obtaining equipment for research in developing countries can be difficult, but it is possible to build some simple equipment with local materials. Onion varietal testing for the export market from Central America has been a major emphasis for the Honduran Agricultural Research Foundation. They have been carrying out evaluations since their inception in 1985, but did not have a good way to consistently grade large quantities of onions. To evaluate the yields, simple low-cost, and easily transportable grading equipment was constructed from materials readily available in the domestic market. Grading equipment must give uniform and repeatable results. Two grading systems were designed to provide that consistency. The first was the use of PVC (polyvinylchloride) tubing to construct 3and 4-inch grading rings. Yellow and sweet onions for export are divided into two classes—jumbo (3-4 inches with 65% 3-1/2 or larger in diameter) and colossal (larger than 4 inches in diameter). Rings were constructed by cutting 1-inch cross-sections of tubing and putting one inside the other until the desired diameter was reached. The rings were functional for small plots, but were not appropriate for large trials. A compact, collapsible grader, easily carried in the back of a small truck or van, was constructed for use on large trials. Local wood and steel bars were used for the section table and sizers. At the same time, growers were looking for a grading system that could be used in areas where there was no electricity. The grader was redesigned for commercial use, but was still portable. The designs for and cost effectiveness of the grading equipment will be discussed.

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