Origin

‘NuMex Fabian Garcia’ (Fig. 1) originates from ‘NuMex Jose Fernandez’, a cultivar released by the New Mexico State Univ. (NMSU) onion breeding program in 1994 (Corgan, 1994). In 1994, bulbs that possessed increased bulb firmness and size, a more rounded bulb shape, and a lighter dry scale color were selected from ‘NuMex Jose Fernandez’ using phenotypic recurrent selection. The selected bulbs were placed together in a crossing cage that was numbered 95-16. The next year, the selected bulbs flowered and pollinators were introduced into the cage and were allowed to pollinate flowers from all plants. Several months later, seed was harvested from each plant, bulked together, and labeled as NMSU 95-16. That fall, seed of NMSU 95-16 was sown. The next February of 1996, resulting plants of NMSU 95-16 were removed from the soil and transplanted to another location. Later that summer, bulbs were selected that possessed superior pink root [causal organism, Phoma terrestris (Hansen)] resistance, an increased bulb size, a more rounded bulb shape, and a later bulb maturity than that of ‘NuMex Jose Fernandez’. The fields used for evaluation have been used for several decades and are assumed to have higher incidence levels of pink root as compared with farmers’ fields. The selected bulbs were placed together in a crossing cage numbered 97-13. The next year, pollinators were introduced into the cage and allowed to pollinate flowers from all plants. Several months later, seed was harvested from each plant, bulked together, and labeled as NMSU 97-13. Seed from NMSU 97-13 was sown the next year and bulb selections were made. Six additional cycles of phenotypic recurrent selection were conducted in 1998, 2000, 2002, 2004, 2006, and 2008. Bulbs were selected for later and more uniform maturity, a more rounded and uniform shape, increased bulb firmness, and additional layers of darker, dry outer scale tissue. For the selections made in 2006 and 2008, 35 and 34 bulbs were selected from NMSU 05-19 and NMSU 07-19-1, respectively. The seed harvested from the 09-20 crossing cage became ‘NuMex Fabian Garcia’.

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Harvested bulbs of ‘NuMex Fabian Garcia’ onion.

Citation: HortScience horts 47, 9; 10.21273/HORTSCI.47.9.1369

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Evaluation Procedures

For 3 years, ‘NuMex Fabian Garcia’ was compared with ‘NuMex Jose Fernandez’ in replicated trials grown in several fields (Table 1). The field soil at the Fabian Garcia Science Center was a Glendale loam and a Brazito very fine sandy loam, thick surface (pH 7.6), whereas the field soil at the Leyendecker Plant Science Research Center was a Glendale loam (pH 7.7). Seeds were sown ≈1 to 2 cm deep in two rows 6 cm apart from late January to mid-February depending on field location and year. For each two-row plot, 1.5 g of seed was sown and plants were thinned to 10 cm between plants within the row. Each plot was 2.4 m long and 1 m wide and separated by an alley of 0.6 m from the next plot on the same bed. The trials were conducted in randomized complete block designs with four replications. Standard cultural practices to produce winter-sown onions in southern New Mexico were followed (Walker et al., 2009). For each field, diammonium phosphate (18N–20P–0K; Helena Chemical Co., Collierville, TN) was applied at a rate of 170 kg·ha⁻¹ before seeding as a band 10 cm below the soil surface. Drip irrigation was used for Trials 2, 3, and 4, whereas furrow flood irrigation was used for Trial 1. Subsurface drip irrigation lines (T Tape; T-Systems International, San Diego, CA), that had emitters every 20 cm, were placed 10 cm deep in the center of each bed. Irrigation was applied as needed. A urea-based liquid fertilizer (26N–0P–0K–6S; Western Blend, Inc., Las Cruces, NM) was applied as needed to Field 1, whereas a fish fertilizer (2.2N–4.4P–0.3K–0.2S; Neptune’s Harvest Fertilizer, Gloucester, MA) was applied as needed to the other fields.

Table 1.

Bulb maturity, marketable yield, average bulb weight, percentage of single centers, and pink root severity of ‘NuMex Fabian Garcia’ as compared with ‘Exacta’ and ‘NuMex Jose Fernandez’ when sown at the Fabian Garcia Science Center or the Leyendecker Plant Science Research Center in Las Cruces, NM, from 2008 to 2011.

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All plots were harvested when 80% of the plants in the plot had lodged. The harvest date was considered the maturity date and the number of days from sowing until harvest was counted for each plot. The root systems of 20 bulbs from each plot were rated for the severity of pink root symptoms on a scale of 1 (no infected roots) to 9 (completely infected roots). After rating, bulbs were placed in mesh sacks and, on the same day, transferred indoors to an onion shed. Bulbs were cured for 3 to 4 d under ambient conditions to reduce storage losses and decay. After curing, the total bulb fresh weight was measured for each plot. Bulbs were graded to remove culls (diseased bulbs, bulbs under 3.8 cm in diameter, split and double bulbs). The number of culls was subtracted from the total bulb number to obtain the marketable bulb number per plot. After bulbs were graded, they were weighed again to obtain marketable bulb weight per plot. The average bulb weight was calculated by dividing marketable bulb weight by marketable bulb number. For 20 bulbs per plot, dry outer scale color, adherence, thickness, and quality were rated for each bulb. Color was rated on a scale of 1 (very light yellow) to 9 (dark brown). Adherence was rated on a scale of 1 (scales easily removed when force is applied) to 5 (scales remained attached to bulb when force is applied). Thickness was rated on a scale of 1 (very thin) to 5 (very thick). Quality was rated on a scale of 1 (poor) to 9 (very excellent). Poor scale quality characteristics included very light dry outer scale color, few scale layers, easily removed dry outer scale such that no scale remained on the bulb, fleshy scale greening, dry outer scale staining or discoloration, and/or nonuniform dry outer scale color. Excellent scale characteristics included tendency to have darker dry outer scale color, multiple dry outer scale layers, excellent scale adherence such that multiple scale layers remain on the bulb after grading, uniform dry outer scale color, absence of dry outer scale discoloration or staining, and/or absence of fleshy scale greening. In addition, the number of dry outer scales that remain on the bulb after grading was recorded for 20 bulbs per plot. After rating for scale characteristics, 20 bulbs per plot were rated for firmness. Bulbs were rated on a scale of 1 (soft) to 9 (hard) when they were squeezed by hand at two separate points at the vertical center. After firmness rating, 25 bulbs were cut transversely at the widest point on the vertical axis to determine the percent of bulbs possessing a single growing point. If a bulb possessed a single growing point or multiple growing points within 1.3 cm of the bulb center, then the bulb was considered single-centered. The F-test in the General Linear Models procedure of the SAS statistical software (SAS Institute, Cary, NC; Version 9.2) was used to determine differences among means of ‘NuMex Fabian Garcia’, ‘Exacta’, and ‘NuMex Jose Fernandez’ for each trait. The Proc Means statement was used to calculate the cultivar means across four replications. Mean separation was performed using Fisher’s protected least significant difference among different entries at the 5% level of significance.

Description and Performance

‘NuMex Fabian Garcia’ is a late-maturing, intermediate-day, open-pollinated, yellow, globe onion that matures from 30 July to 21 Aug. when winter-sown in Las Cruces, NM (Table 1). Suggested planting dates at Las Cruces are 15 Jan. to 28 Feb. In three of the four environments tested, bulbs of ‘NuMex Fabian Garcia’ matured later than bulbs of ‘NuMex Jose Fernandez’ and matured at a similar time as ‘Exacta’ (Table 1). In each environment, ‘NuMex Fabian Garcia’ produced a greater marketable yield than ‘NuMex Jose Fernandez’. When grown using drip irrigation, ‘NuMex Fabian Garcia’ produced a greater or comparable bulb yield as ‘Exacta’. In addition, ‘NuMex Fabian Garcia’ produced a greater average bulb size than ‘Exacta’ in two drip irrigation environments (Table 1). The percentage of single-centered bulbs produced by a cultivar is an important bulb quality trait to consider when selecting a cultivar for propagation because many onions are processed into onion rings in the United States. Onion ring processors request a high percentage of single-centered bulbs when purchasing onion bulb shipments for processing. ‘NuMex Jose Fernandez’ currently produces a high percentage of single-centered bulbs. ‘NuMex Fabian Garcia’ produced a higher percentage of single-centered bulbs than ‘NuMex Jose Fernandez’ in two of the four environments tested (Table 1). The percentage of single-centered bulbs was similar for ‘Exacta’ and ‘NuMex Fabian Garcia’. Bulbs of ‘NuMex Fabian Garcia’ exhibit a similar expression of pink root symptoms as bulbs of ‘Exacta’ and ‘NuMex Jose Fernandez’. In three of four environments tested, pink root severity ratings were similar for all cultivars (Table 1). When grown using furrow irrigation, bulbs of ‘NuMex Fabian Garcia’ expressed fewer pink root symptoms than bulbs of ‘Exacta’ or ‘NuMex Jose Fernandez’.

Because scale characteristics and bulb firmness were important characters evaluated during the selection process, the scale color, adherence, thickness, number, and quality, and bulb firmness of ‘NuMex Fabian Garcia’ were compared with the same characters for ‘NuMex Jose Fernandez’ for 2 years and ‘Exacta’ for 1 year (Table 2). Bulb dry outer scale color, thickness, and number were similar among the three cultivars. For the second year, bulbs of ‘NuMex Jose Fernandez’ had a greater scale adherence than bulbs of ‘Exacta’ or ‘NuMex Fabian Garcia’. Also for the second year, bulbs of ‘Exacta’ and ‘NuMex Fabian Garcia’ were rated as having better scale quality than bulbs of ‘NuMex Jose Fernandez’. Bulbs of ‘NuMex Fabian Garcia’ were less firm than bulbs of ‘NuMex Jose Fernandez’ in the second year. In terms of bulb shape, bulbs of ‘NuMex Fabian Garcia’ were greater in height or possessed more “depth” than bulbs of ‘NuMex Jose Fernandez’ (Table 3). Bulbs of ‘NuMex Fabian Garcia’ had a greater shape index than bulbs of ‘Exacta’. As the bulb shape index approaches one, the bulb height and diameter become more similar and the shape becomes more completely round. Bulbs that are more globe-shaped (round, bulb shape index = 1.00) are more desired commercially than those that are flat globe-shaped (bulb shape index less than 1.00).

Table 2.

Scale color, adherence, thickness, number, and quality ratings and bulb firmness rating of ‘NuMex Fabian Garcia’ as compared with ‘Exacta’ and ‘NuMex Jose Fernandez’ when grown at the Fabian Garcia Research Center, Las Cruces, NM, in 2009 and 2011.

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Table 3.

Bulb height, diameter, and shape index of ‘NuMex Fabian Garcia’ as compared with ‘Exacta’ and ‘NuMex Jose Fernandez’ when grown at the Fabian Garcia Research Center, Las Cruces, NM, in 2009 and 2011.

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Availability

Currently, ‘NuMex Fabian Garcia’ is being offered for exclusive release. Interested parties should contact C.S. Cramer, Dept. of Plant and Environmental Sciences, MSC 3Q, Box 30003, New Mexico State Univ., Las Cruces, NM 88003. An application for plant variety protection will be filed.