GRADE DISTRIBUTION OF SWEET ONIONS HARVESTED AT DIFFERENT MATURITIES

Abstract

Recognizing that onions are marketed by grade and weight within a grade, a study was conducted to examine thebenefits of harvesting sweet onions at an optimal harvest maturity in terms of both the number and weight of those onionswithin a grade. Sweet onions were harvested over seven years at three levels of harvest maturity: early, optimal, or late, withapproximately two weeks between each of the three harvests. Following harvest, all onions were cured before they wereexamined, graded and weighed. Grades, determined by size screening, were <63.5 mm (small), 63.5 to 76.2 mm (medium),76.2 to 88.9 mm (large), and >88.9 mm (jumbo). The mean onion bulb weight for each grade size was 74.9 g (small), 134.5 g(medium), 204.8 g (large), and 315.8 gjumbo. The percentage weight of large onions remained approximately the same at29, 27, and 27% of the total harvest weight for early, optimal, and late harvest maturities, respectively. The percentage weightof jumbo onions dramatically increased from 28 to 48% of the total harvest weight between the early and optimal maturities,and a greater number of large and jumbo grade onions were found at the optimal harvest maturity than at either the earlyor late harvest maturities. In addition, the percentage weight of jumbo onions declined to 46% at the late harvest. Incomparison with harvesting sweet onions at an either early or late maturity it was proven beneficial to harvest at an optimalmaturity in order to gain the highest yield in terms of grade and weight within a grade.