'NuMex Freedom' is a low pungency, short- to intermediate-day, yellow grano type onion that matures from June 25 to July 1 when fall seeded or spring transplanted in Las Cruces, NM. Suggested planting date at Las Cruces is October 1. 'NuMex Freedom' also can be spring seeded for July 8-10 maturity, but the bulb size is smaller than from fall seeding. 'NuMex Freedom' has excellent yield, pink root resistance, and bolting resistance. From fall seeding, 'NuMex Freedom' matures about 3 weeks later than 'NuMex Starlite' and 'NuMex Dulce'. 'NuMex Freedom' is the only low pungency onion in its maturity class that can be fall seeded to produce high yields of 'sweet' onions for marketing from late June to mid-July. 'NuMex Freedom' originates from a 1988 intercross between yellow grano and sweet Spanish types. 'NuMex Sunlite' and other bolting resistant selections from 'Texas Grano 502 PRR' were parents, as well as some later maturing bulbs from sweet Spanish origin. Seed was collected and planted in 1989. Bulb selections were made within the population in 1990 for late-June maturity, pink root resistance, and bulb shape. The main index for onion maturity is collapse of the tissues in the neck, resulting in lodging of the foliage. Selections were made for maturity in late June in Las Cruces, N.M. when fall seeded. Selection for pink root resistance was accomplished by growing onion populations in soil severely infested with the pink root fungus. Bulbs with less than 20% pink roots were selected. Selected bulbs were intercrossed to produce seed.
In 1992, the population was selected for bulb shape, size, and firmness, late-June maturity, pink root resistance, single centers, and low pungency. Pungency was measured in the laboratory using the pyruvic acid (PA) technique. Low PA production is correlated with low sensory perception of pungency. Single centers were evaluated by cutting each bulb transversely at the equatorial plane. Any bulb with one or two growing points within the center diameter of 2.5 cm was considered to be single-centered. The top portions of bulbs were analyzed for PA, and the bottom portions were saved for selected bulbs. Only bulbs with pungency levels less than 4.0 µ mol PA/ml juice were selected. The mean pungency of the selected bulbs was 3.7 µ mol PA/ml juice. These bulbs were intercrossed in an isolation cage, and the seed was collected from each maternal plant in 1993. The population was designated as 93-52 and consisted of 35 maternal, half-sib progeny lines. Seed of the half-sib lines was fall-planted for bulb production, and another cycle of phenotypic recurrent selection was made in the field and laboratory in 1994. Selection was made among and within half-sib lines in 1994. The selected bulbs had a mean pungency of 3.25 µ mol PA/ml juice and were intercrossed to produce 95-2 seed. In 1996, the latest maturing bulbs in the population were selected, and another cycle of recurrent selection was made for bulb shape, size, and firmness, pink root resistance, single centers, and low pungency. The selected bulbs had a mean pungency of 3.4 µ mol PA/ml juice and were intercrossed to produce 97-27 seed. In 1998, the pungency of 97-27 bulbs was uniformly low; 100 bulbs were selected with a mean pungency was 1.3 µ mol PA/ml juice. These bulbs were intercrossed to produce 99-26 seed. Seed of 99-26 was planted for a seed-to-seed increase to produce foundation seed of 'NuMex Freedom' in 2000.
[Note: µ mol PA/ml = micromole of Pyruvic Acid per milliter]