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Abstract

A field study was conducted to determine the effects of rhizobial inoculation (cowpea ‘EL’ mixed strain) and N-fertilization with 100 kg/ha nitrate nitrogen (CaNO3 — 15.5% N) on seed and biomass yield in cowpea [Vigna unguiculata (L.) Walp.]. Four indeterminate cultivars, ‘Mississippi Silver’, ‘California Blackeye #5’, ‘Lady’, ‘Brown Crowder’, and one determinate, early maturing cultivar, ‘Bush Purple Hull’, were used. Seed yield in inoculated and N-fertilized plants was significantly greater than that of the unfertilized, uninoculated control treatment. Generally, yield of inoculated plants was equivalent to or greater than that obtained with 100 kg N. The indeterminate cultivars yielded more biomass than did ‘Bush Purple Hull’ in all 3 treatments. Seed yield was higher in the indeterminate cultivars with inoculation or N-fertilization than in ‘Bush Purple Hull’; however, there were no significant differences in seed yield among cultivars in the control treatment. Harvest index in the indeterminate cultivars was increased by inoculation but not by N-fertilization. Harvest index of ‘Bush Purple Hull’ was at least 3 times higher than the indeterminate cultivars. Among the major seed yield components, only pods/plant was influenced by all 3 treatments, whereas seeds/pod and seed weight were fairly stable and cultivar specific. Standardized regression analysis revealed that pods/plant was the major component which accounted for the variability in seed yield of inoculated plants within a cultivar, but not in ‘Bush Purple Hull’, where dry matter accumulation/plant/day was the major component. Factor analysis on the yield and N2 fixation components also indicated that cowpea cultivars behaved differently in the expression of traits which influenced seed yield. A measure of genetic divergence among these cultivars using Mahalanobis distances confirmed that the 5 cowpea cultivars differed significantly.

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Abstract

Scanning electron microscopy (SEM) and light microscopy (LM) studies were made on pollen samples of selected cultivars of Vitis labruscana Bailey and V. vinifera. Pollen differed in size, shape, and exine characteristics. The majority of cultivars had tricolporate (3-furrowed) pollen, except “abnormal” types which lacked the furrows (colpi). Based on exine and furrow characteristics, shape, and polar axis/equatorial diameter (P/E) ratios of pollen, cultivars were divided into 3 shape groups. Cultivars with pollen lacking furrows were grouped as “abnormal”. Pollen shape and P/E ratios were better parameters to aid in grape ampelography than exine patterns and furrow characteristics.

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Abstract

Fifty-four apple (Malus domestica Borkh.) cultivars were characterized electrophoretically using 6 isozyme systems. Intracultivar variation in isozyme phenotype was not observed, whereas intercultivar polymorphism was sufficient to permit reliable and unambiguous identification of nearly every cultivar. The most useful isozyme systems for distinguishing among the cultivars were 6-phosphogluconate dehydrogenase and aspartate aminotransferase. Sports could not be distinguished from the original cultivar. The genetic basic of several polymorphisms was known, enabling the comparison of the isozyme genotype observed in a hybrid with that predicted on the basis of parental genotypes. The 6-phosphogluconate dehydrogenase genotype of ‘Spartan’ indicated that ‘Yellow Newtown’ may not have been the paternal parent.

Open Access

The effects of pollination treatments on fruit set and five berry characteristics [mass, diameter, number of apparently viable seeds (well-developed, plump with dark seed coat), total seed number (includes apparently viable and partially developed seeds), and harvest date] were examined on three highbush blueberry cultivars. Pollination treatments included unpollinated, open pollinated, emasculated, and three hand pollinations that used pollen from the same flower, from the same cultivar, or from a different cultivar. Berries matured earliest and were smallest with the most apparently viable seeds in `Northland', `Patriot' had the greatest fruit set and smallest seed number, and `Bluecrop' matured the latest. Fruit set was greater, berry size larger, seed number smaller, and maturation later in 1990 than 1991. For all three cultivars, berries were generally smallest, latest maturing, and had the fewest seeds when pollination was prevented and were largest with the most seeds and earliest maturing in open visitation. Emasculation resulted in berries similar to those from unpollinated flowers. For berry characteristics, cross-pollination was of benefit for `Patriot' and possibly `Northland' but not `Bluecrop'. Thus, commercial highbush blueberry planting designs must be based on the pollination requirements of the particular cultivar. `Northland' berries almost always had seeds, while `Patriot' showed high levels and `Bluecrop' low levels of parthenocarpy.

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Heterotic patterns in sweet corn are weakly defined. Most sweet corn inbreds are descended from three open-pollinated cultivars: `Golden Bantam', Stowell's Evergreen', and `Country Gentleman'. Heterotic and phylogenetic relationships among these three cultivars and others are not clearly known. This investigation was designed to investigate the heterotic patterns among some historically important open-pollinated sweet corn cultivars: `Country Gentleman', `Golden Bantam', `Lindsey Meyer Blue', `Stowell's Evergreen', `Howling Mob', and `Pease Crosby'. The 15 possible hybrids from the diallel cross plus the 6 parents were grown in midspring and late summer plantings. Heterosis and combining ability effects were estimated for 13 traits. Hybrid × planting date interactions were significant for most of the main traits, hence, planting dates were analyzed separately. Average midparent heterosis for grain yield was 29.17% in the first planting date and 57.04% in the second planting. Midparent heterosis for yield and plant height were highest for hybrids with `Country Gentleman' as a parent. `Stowell's Evergreen' when crossed to `Pease Crosby', `Lindsey Meyer, and `Golden Bantam' exhibited high heterosis. The two late-maturity cultivars `Country Gentleman' and `Stowell's Evergreen' had higher general combining ability than the four early-maturity cultivars for most traits. Specific combining ability was seldom significant. Yield of `Country Gentleman' hybrids averaged over all crosses and planting dates was the highest. These data indicate a strong heterotic pattern—`Country Gentleman' × `Pease Crosby', `Golden Bantam', and `Lindsey Meyer Blue'—and a weaker one—`Stowell's Evergreen' × `Pease Crosby', `Golden Bantam', and `Lindsey Meyer Blue'.

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Stomatal density of pods and leaves were determined for six commercial snap bean cultivars (Phaseolus vulgaris L. `Evergreen', `Hystyle', Labrador', `Tenderlake', `Top Crop', and `Venture') grown at three planting dates, in an attempt to find morphological traits that could be related to cultivar differences in pod Ca concentration. Snap beans were planted three times at ≈1-week intervals beginning 15 June 1995, and harvested 59 to 62 days after planting. Stomatal counts were performed using a microscope linked to a video camera, and Ca concentration determinations were made using atomic absorption spectrophotometry. Calcium concentration and stomatal density of leaf tissue was higher than that of pods. Cultivar differences for pod Ca concentration (P = 0.001) and stomatal density (P = 0.001) were observed although cultivars with higher pod stomatal density did not necessarily result in higher pod Ca concentration. Calcium concentration and stomatal density for leaves did not differ among cultivars. Stomatal density and Ca concentration of pods were positively correlated (R 2 = 0.37), while pod maturity was negatively associated to both pod Ca concentration (R 2 = 0.93), and pod stomatal density (R 2 = 0.99). The effect of planting dates was absent in pod Ca concentration and significant in pod stomatal density.

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Six cross-incompatibility groups, which contain most of commercially important California almond cultivars [Prunus dulcis (Mill.) D.A. Webb, syn. Prunus amygdalus Batch], and their self-incompatibility (S) allele genotypes are identified. Incompatibility groups include `Mission' (SaSb), `Nonpareil' (ScSd), and the four groups resulting from the `Mission' × `Nonpareil' cross: (SaSc), (SaSd), (SbSc), and (SbSd), as represented by `Thompson', `Carmel', `Merced' and `Monterey', respectively. All seedlings from the `Mission' × `Nonpareil' cross were compatible with both parents, a result indicating that these two cultivars have no alleles in common. Crossing studies support a full-sib relationship for these progeny groups and the origin of both parents from common germplasm. Cultivars in these six groups account for ≈ 93% of present California production, a result demonstrating a limited genetic base for this vegetatively propagated tree crop.

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Abstract

Starch gel electrophoresis was employed to distinguish the University of California-released strawberry cultivars. Isozyme patterns of 3 enzyme systems (PGI, LAP, and PGM) were studied. Fourteen of the 22 cultivars studied were classified uniquely by using the 3 enzyme systems. The use of electrophoresis as a tool in breeding clonally propagated crops is discussed.

Open Access

program at the University of Florida to develop specialty pepper cultivars with improved quality related to shape, color, flavor, and health-promoting phytochemicals. Although previous genetic research has revealed the inheritance of many horticultural

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Variation in amount and composition of epicuticular wax among several apple (Malus ×domestica Borkh.) cultivars was characterized by gas chromatography, thin-layer chromatography, and gas chromatography-mass spectroscopy. Across cultivars, wax mass ranged from 366 to 1038 μg·cm-2. Wax mass decreased during the 30 days before harvest. Ursolic acid accounted for 32% to 70% of the hydrocarbons that make up the epicuticular wax. Alkanes, predominantly 29-carbon nonacosane, comprised 16.6% to 49%. Primary alcohols of the hydrocarbons ranged from 0% to 14.6% of the epicuticular wax. Secondary alcohols of the hydrocarbons were the most cultivar specific, making up 20.4% of the epicuticular wax in `Delicious' and only 1.9% `Golden Delicious' strains. Aldehydes and ketones of the hydrocarbons represented a small amount of total wax, ranging from 0% and 6.0%. Percentage of primary alcohol in the epicuticular wax increased as fruit developed. Other components showed no distinct trends with fruit development. Examination of the ultrastructure of cuticular wax using scanning electron microscopy revealed structural differences among cultivars.

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