Eighteen hybrid onion and 23 open-pollinated (OP) varieties were tested in southern New Mexico for plant characteristics, disease resistance, and bulb yield in order to determine if hybrid varieties outperformed OP varieties. Varieties were short- to intermediate-day in their bulbing response and were planted in the fall seasons of 1997 and 1998 and harvested the following May or June. Varieties were grouped based upon their relative maturity for fall-planted onions grown in southern New Mexico (early, intermediate, late). They were planted two (1998) or four (1997) rows per plot with plots being 8 ft (2.5 m) long and 22 inches (56 cm) wide. Plant stand per plot, plant height of seven plants, and leaf number of seven plants were measured 164 d after planting. Plots were harvested when 80% of the plant tops had fallen across all four replications of a single population. At harvest, number of seedstalks, number of bulbs, pink root incidence, and total bulb weight per plot were recorded. After removing culls, the percentage of marketable bulbs, marketable bulb yield, and average bulb size were determined. Hybrid varieties outperformed OP varieties for plant height, and leaf number but not for percentage of seedstalks, pink root incidence, percentage marketable yield, bulb size, and marketable bulb yield. In this study, most OP varieties perform as well or better than most of the hybrid varieties.
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