The color of onion ( Allium cepa ) bulbs is one of the most important consumer traits, and bulb colors can be white, yellow, red, or chartreuse ( El-Shafie and Davis, 1967 ). White bulbs are conditioned by a dominant allele at the inhibitor ( I
Bulb color in onion is an economically important trait and is conditioned by the interaction of at least five major loci ( Clarke et al., 1944 ; El-Shafie and Davis, 1967 ; Reiman, 1931 ). White bulbs result from a dominant allele at the I
bulbs can persist in zoysiagrass ( Zoysia japonica Steud.) and bermudagrass ( Cynodon dactylon ) in transition zone environments, providing color and biodiversity to dormant turfgrass situations. However, both studies examined a small number of bulb
; garlic bulbs resulting from seed stock purchased in other regions often do not display the characteristics such as bulb size, shape, and color that were listed in the catalogs. This is a result of the high degree of variability in clove wrapper color
not be commercially acceptable in the U.S. onion market as a result of their undesirable bulb shape, small bulb size, bulb shape and size variability, low percentage of single-centered bulbs, bulb scale color variation, and bulb maturity variation
found on either leaves or seedstalks reduce leaf photosynthetic area. This reduction decreases onion bulb size and yield of larger bulb classes or causes premature seedstalk lodging that in turn reduces seed yield ( du Toit et al., 2004b ; Gent et al
(Allium cepa × A. fistulosum) × A. cepa breeding lines have been established to the fourth generation. The aim is to develop an A. cepa-like bulbing onion carrying A. fistulosum genes. Seven populations were characterized for morphological traits and three isozyme markers. Each bulb from the populations was characterized for maturity, soluble solids content, bulb shape, and bulb color. All the populations produced A. cepa-like bulbs. Significant variation was observed within each population for each morphological trait. All the bulbs were screened for the presence of A. cepa and A. fistulosum alleles of alcohol dehydrogenase (Adh-1), esterase (Est), and phosphoglucoisomerase (Pgi-1). Allium cepa Adh-1, Est, and Pgi-1 alleles were observed in all the populations. One population, 951026-8, contained plants heterozygous for A. cepa and A. fistulosum Pgi-1 alleles. Recovery of these fourth generation Allium backcross plants demonstrates introgression of the A. fistulosum genome into an A. cepa-like bulbing onion.
Heritability estimates of bolting percentage (BP), pink root (PR) and Fusarium basal rot (FBR) incidences, and percentage of single centered (PSC) bulbs were calculated for an intermediate-day, open-pollinated onion population using selection response and half-sib (HS) family analyses. BP was determined by counting the number of seedstalks per plot when the population was seeded at an earlier planting date to induce bolting. PR and FBR incidences were determined by rating 30 bulbs/plot for the severity of PR and FBR, and calculated an incidence rate from the number of infected bulbs out of 30 rated. The PSC bulbs was determined by cutting transversely 30 bulbs at the vertical center of the bulb and looking for the presence of a single growing point or multiple growing points within 1.3 cm from the center of the bulb. Families were also evaluated for bulb quality that consisted of shape, size, maturity, firmness, number of scale layers, and dry outer scale thickness, adherence, retention, and color. Families were selected based upon an index that equally weighted BP, PR and FBR incidences, PSC bulbs, and bulb quality. No progress was made for BP even though the narrow sense heritability (h2) estimate was 0.51. PR and FBR incidence was reduced by 18% and 12%, respectively, and realized heritability (RH) estimates of 0.65 and 0.60, respectively, were calculated. h2 estimates calculated through HS family analysis was 0.46 and 0.37, respectively, for these two traits. Very little progress was made for the PSC bulbs and this was reflected in a RH estimate of 0.17. However, the h2 estimate was 0.71, suggesting that progress should be possible.
’, 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
conducted to develop ‘NuMex Mirage’. The selection criteria for these cycles of selection and any other previous selection conducted were for pink root and fusarium basal rot resistance, bolting resistance, clean white dry scale color, lack of bulb scale