Search Results

You are looking at 1 - 7 of 7 items for

  • Author or Editor: David B. Rubino x
Clear All Modify Search
Author:

Segregating lisianthus [Eustoma grandiflorum (Griseb.) Shinn.] progeny were evaluated to determine the inheritance of esterase (EST), diaphorase (DIA), and glucose-6-phosphate isomerase (GPI) isozymes. Phenotypic data supported the hypotheses that EST is monomeric and controlled by one locus (Est1) with at least three alleles, DIA is tetrameric and controlled by one locus (Dia2) with at least two alleles, and GPI is controlled by one locus (Gpil) with at least two alleles. The structure of the GPI isozyme could not be inferred from banding patterns. Joint segregation analyses indicated that the three loci segregate independently. These three isozymes are the first simply inherited, unlinked biochemical markers identified in lisianthus. These marker loci will be useful for genetic studies, breeding, and germplasm characterization.

Free access
Author:

Fifteen cultivated genotypes of Exacum affine Balf. were evaluated for flower development and for flower and leaf color at 0 days (marketable stage, ≈ 25% of plant canopy covered with flowers), and after 14 and 28 days of maintenance in a low-irradiance environment (≈ 1 μmol·m-2·s-1 photosynthetically active radiation from cool-white fluorescent lights for 12 hours daily). Flowering and flower color development were reduced, but leaf color improved during maintenance under low irradiance. Variability was observed among the 15 genotypes for flower bud and flower color development in a low-irradiance environment.

Free access
Author:

Genotype × season interaction was investigated for days to first flower and full bloom and flower and plant diameter for 15 exacum cultivars and breeding lines produced in two glasshouses during winter and summer growing seasons. Genotype x season interactions were significant (P < 0.01) for all four characteristics. Genotype rankings for time to flowering and plant diameter varied greatly depending on the growing season; evaluation during the target growing season is recommended when selecting among exacum genotypes for these characteristics.

Free access
Author:

Segregating progenies from controlled pollinations of Eustoma grandiflorum Griseb. were investigated to determine the inheritance of diaphorase (DIA) and glucoses-phosphate isomerase (GPI) isozymes. Phenotypic data supported the hypotheses that DIA1 is tetrameric and is controlled by a single locus with two alleles (Dia1-1 and Dia1-2) and that GPI1 is dimeric and also is controlled by a single locus with two alleles (Gpi1-1 and Gpi1-2). Examination of isozyme phenotypes for over 70 cultivars of E. grandiflorum revealed polymorphism for DIA1 and GPI1. These isozymes may be useful for marker-assisted selection and cultivar identification.

Free access

This study was conducted to investigate the effects of mild mass selection for adaptation on the performance, genotypic variance, combining ability, S1 family-testcross correlation, and midparent heterosis of S1 families derived from a sweet corn (su) × tropical maize (Zea mays L.) composite (Composite 1R). Four cycles of random mating followed by 10 cycles of 10% stratified mass selection were conducted for earliness, plant and ear type, and freedom from pests. Selection significantly (P < 0.01) decreased plant height, ear height, percentage barrenness, and ear length, and significantly (P < 0.01) increased stalk breakage, earliness (Celsius heat units to 50% anthesis and silking), and kernel row number of both S1 families and their testcrosses. Juvenile plant height at 45 days after planting increased in testcrosses only. Percentage tip blanking and pericarp thickness did not change. For most traits, the greatest response occurred during the first five of 10 selection cycles. Cycle 10 testcrosses performed at least as well as elite check testcrosses for eight of 10 traits. The tropical parents improved combining ability for increased juvenile plant height and kernel row number, and decreased percentage of stalk breakage. As a result of selection, genotypic variance among S families decreased by >40% for heat units to 50% anthesis and silking, ear height, and percentage of barrenness, although for all traits measured, significant genotypic variation persisted following 10 cycles of mass selection for adaptation. S1-testcross correlations and percentage midparent heterosis tended to be consistent across selection cycles. Five cycles of mild stratified mass selection increased the adaptation of a temperate sweet corn × tropical maize composite to the temperate zone of the United States while maintaining significant genotypic variation.

Free access

Seedlings of commercial lisianthus cultivars form rosettes when grown at 25 to 28°C. Rosetted plants have a basal cluster of leaves, very short internodes typical of biennials, and do not bolt or flower for months without being exposed to 3 to 4 weeks at <15 to 18°C to reverse heat-induced rosetting. Semirosetted plants develop when seedlings are grown at a constant 22 to 25°C or at <22°C night with >28°C day. Semirosetted plants have one or more side shoots which may elongate and flower, but plants flower unpredictably and are of poor quality as cut flowers or potted plants. `Maurine Blue' and Florida Blue' were released from the Univ. of Florida in 1995. To our knowledge, they are the first heat-tolerant lisianthus cultivars. Seedlings and plants can be grown at 28 to 31°C without rosetting. `Maurine Blue' ranged in height from 38 cm (summer) to 67 cm (spring) during 1994 and 1995 production trials in Florida. `Maurine Blue' has potential for use as a tall bedding plant if sold as green transplants, a flowering potted plant if grown with three plants per 15-cm-diameter pot with a growth retardant, or as a bouquet-type cut flower. `Florida Blue' plants (38 cm) grown in an 11.5-cm square pot (0.65-L) with capillary mat irrigation were similar in height to `Blue Lisa' (32 cm) and taller than `Little Belle Blue' (22 cm) and `Mermaid Blue' (24 cm). `Florida Blue' was designated as a semi-dwarf cultivar with an intended use as a bedding plant. Growth retardants would be useful for production in pots <10 to 12 cm in diameter. Complete descriptive information, photographs and pedigrees will be presented.

Free access