NuMex Solano was developed by Chris Cramer and Joe Corgan of the Department of Agronomy and Horticulture. NuMex Solano is an open-pollinated, late maturing, single-centered, high yielding, pink root and bolting resistant, firm to hard, white round onion for fall seeding in southern New Mexico. It originates from four individual paired crosses between a bolting-resistant selection of Ben Shemen and Southport White Globe in 1979. Seed was collected from the Ben Shemen parents and planted. The following year, white-colored bulbs were selected. The selected bulbs were intercrossed and the resulting seed was planted in 1981. In 1982, all yellow bulbs were selected from the population and were intercrossed in 1983. The resulting seed was collected and planted. In 1984, a group of white bulbs that were highly variable for bulb shape, bulb maturity, and pink root resistance, were selected and intercrossed the following year. The progeny were all white. The genetics for this white bulb color is iiccyy (recessive white). In 1986, 1988, 1990, 1992, 1994, 1996, 1998, and 2000, selections were made using phenotypic recurrent selection, and each year’s selections were intercrossed to form the next generation. For each selection, bulbs that possessed early, uniform maturity; pink root and bolting resistance; round, uniform shape; hard bulb firmness; and clear white scale color were selected. For the last three selections, bulbs were selected that possessed a single growing point when cut transversely at the vertical center of the bulb.

NuMex Solano is an intermediate-day, round onion that matures from June 13 to June 21 when fall seeded in Las Cruces, NM. Suggested planting dates at Las Cruces are September 20 to October 1. 'NuMex Solano' has excellent yield, firmness, pink root resistance, bolting resistance, high percentage of single-centered bulbs, round shape, good scale quality, and mid-to-late June maturity. ‘NuMex Solano’ matures later than any other fall seeded white onion cultivar.

Replicated field trials were conducted in 1997-1998 (NMSU 97-12), 1998-1999 (NMSU 97-12), 1999-2000 (NMSU 99-99), and 2000-2001 (NMSU 99-99) comparing NuMex Solano to NuMex Crispy. The results showed that NuMex Solano produced later maturing bulbs and a higher percentage of single centered bulbs than NuMex Crispy in each year. The bolting resistance of NuMex Solano was similar to or greater than NuMex Crispy depending on the year tested. NuMex Solano produced a high percentage of marketable bulbs, high yield, and large bulb size that was comparable to NuMex Crispy. The pink root severity of NuMex Solano was low and comparable to NuMex Crispy in most years. The higher pink root ratings for NuMex Solano in two years was likely due to later maturity in warmer weather, resulting higher level of disease pressure.

Currently, NuMex Solano is being offered for exclusive release to an interested party. Interested parties should contact the New Mexico Crop Improvement Association, MSC 3CI, Las Cruces, NM 88003.