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- Author or Editor: Thomas G. Byrne x
Seven enzyme systems were examined in 69 apricot [Prunus armeniaca L. and P. mandshurica (Maxim.) Koehne] clones. Three enzymes (6-phosphogluconate dehydrogenase, phosphoglucose isomerase, and phosphoglucomutase) were polymorphic at five loci. Only seven clones were characterized uniquely by their isozyme phenotypes and 56% fell into two of the 15 phenotypic groups found. Isozyme variability in apricot was greater than in peach, but less than that reported in plum or almond.
Flower bud initiation of herbaceous peony (Paeonia L.) may start soon after the current year’s flower anthesis in June; buds continue to develop until the onset of dormancy in the fall. Flower formation, days to harvest, foliage senescence, and dormancy are unaffected by photoperiod. Flower bud dormancy can be broken by storage of dormant plants for a minimum of 4 weeks at 5.6°C after which they may bloom in the greenhouse in 8 to 10 weeks. Increasing storage time to 6 weeks or reducing the temperature to 1° increases the total number of shoots that grow after forcing.
Twenty-nine Japanese-type plum clones were assayed for isozymic variability for eight enzyme systems. Glutamate dehydrogenase (GDH), leucine amino-peptidase (LAP), malate dehydrogenase (MDH), phosphoglucose isomerase (PGI), phosphoglucomutase (PGM), and peroxidase (PX) showed variability among the plums surveyed. 6-phosphogluconate dehydrogenase (6PGD) and triosephosphate isomerase (TPI) were not variable. Isozymic characterization uniquely identified 38% of the clones. The remainder separated into groups of two to three clones that were distinguishable using vegetative morphological characteristics. Reported parentage of five out of nine plums examined was not consistent with their isozymic genotypes.
Shoots of ‘Cara Mia’ rose (Rosa hybrida L.) arising from buds higher on the parent shoot become salable more quickly than those arising from lower buds. Those developing above the 10th or below the 6th true leaf are shorter, of smaller diameter and weigh less. Shoot development is also strongly influenced by shoot diameter at the point of origin. Larger parent shoots give rise to shoots that become salable more quickly, are longer, weigh more, and are larger in diameter than those from smaller parent shoots. Buds from larger-diameter shoots are of larger diameter and have more leaf primordia than those from smaller-diameter shoots, but the diameter of their apical dome is not greater.
A series of diploid plum (Prunus salicina Lindl. and hybrids), apricot (P. armeniaca L.), and plum × apricot (plumcot) clones were surveyed for six enzyme systems to identify a biochemical marker system for plumcots. Peroxidase (EC 1.11,1.7) was the best marker for identifying plum × apricot hybrids. The other systems contained plum or apricot specific alleles useful in verifying hybrid parentage of first or later generation derivatives.
Ligule color of a Gerbera jamesonii H. Bolus ex Hooker population was analyzed with a reflectance spectrophotometer having a spectral capability of 400 to 700 nm and a cv <3% for the variables hue, chroma, and value. The observations for each variable had a continuous distribution; these broad distributions are possibly bimodal. The repeatability of hue, chroma, and value, determined as the correlation between measurements made on plants in December and those made on the same plants the following April, are 0.83, 0.82, and 0.86, respectively. The phenotypic correlations between value and chroma, value and hue, and chroma and hue are -0.35, 0.73, and 0.11, respectively. Some possible biochemical implications concerning the interaction of anthocyanin and carotenoid pigments are discussed. Reflectance spectroscopy and Commission International de l'Eclairage 1976 (L* a* b*) color space notation provide an objective and precise method for incorporating color into a recurrent selection program.
The frequency distribution of gerbera flower hue in the Davis population of gerbera appears continuous and bimodal. This suggests that a gene of large effect may be segregating in a background of polygenic variation. CSA is a statistical technique developed in genetic epidemiology for investigating such complex traits without the need of inbred lines. The REGC program of SAGE (Elston, LSU Medical Center, New Orleans) uses the regressive models of G. Bonney (1984) through pedigree analysis to provide estimates of major gene parameters and residual correlations among relatives. Pedigrees obtained from generations 14, 15, and 16 indicate that a major dominant gene for hue is segregating and accounting for -0.66 of the total variation. The genotypic means are 32 degrees and 71 degrees for the aa and bb genotypes, respectively. The a allele is dominant to the b allele and has a frequency of 0.55. The residual parent-offspring correlation estimate is 0.2 and measures the genetic contribution to the remainder of the variance.
The frequency distribution of gerbera flower hue in the Davis Population of Gerbera appears continuous and bimodal. This suggests that a gene of large effect may be segregating in a background of polygenic variation. CSA is a statistical technique developed in genetic epidemiology for investigating such complex traits, without the need of inbred lines. The REGC program of SAGE (Elston, LSU Med. Center, New Orleans) utilizes the regressive models of G. Bonney (1984) through pedigree analysis to provide estimates of major gene parameters and residual correlations among relatives. Pedigrees obtained from generations 14, 15, and 16 indicate that a major dominant gene for hue is segregating and accounting for ∼ 0.66 of the total variation. The genotypic means are 32 degrees and 71 degrees for the aa and bb genotypes, respectively. The `a' allele is dominant to the `b' allele and has a frequency of 0.55. The residual parent-offspring correlation estimate is 0.2, and measures the genetic contribution to the remainder of the variance.
The development of gerbera (Gerbera jamesonii H. Bolus ex. Hooker) as a floricultural crop is traced from its collection as a botanical novelty in South Africa to its establishment as a commercial crop in the 1930s. The origin of the cultivated germplasm, G. jamesonii and G. viridifolia (DC) Schultz- Bipontinus, is discussed, as well as breeding work that occurred in Europe and the United States. The contributions of the two species to the cultivated germplasm is unknown. Early breeding in Europe was conducted by RI. Lynch at the Cambridge Botanic Gardens in England, R. Adnet at La Rosarie in Antibes, France; and by C. Sprenger in Italy. In the United States, early work was done at estates in New Jersey by Herrington and Atkins, and by the commercial growers Jaenicke and the J.L. Childs' Seed Co. Establishing the cold hardiness of the crop for temperate climates was an early goal of horticulturists and breeders. Much of the cultivated germplasm can be traced to material that passed through Cambridge and Antibes.
Plants of the ‘Cara Mia’ rose (Rosa hybrida L.) grown at elevated day temperatures with long photoperiodic cycles or at reduced night temperature with short photoperiods differed in shoot growth rate, petal number, final stem length, and harvest date when compared to plants grown at suggested day and night temperatures. Node number remained nearly constant under all growing conditions. Plants of ‘Town Crier’ rose grown with a night temperature of 13°C (minimum) during the first 3 weeks following shoot removal produced flowering shoots of the same length in the same amount of time as did those grown at a minimum night temperature of 17°C throughout shoot development. Cooler night temperatures during the second 3-week period after shoot removal increased flower development time by four days but did not affect stem length. Results indicate that some rose cultivars can tolerate lower than normal night temperatures for a portion of the growing cycle without reduced growth and/or yield.