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  • Author or Editor: M. Pooler x
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Mepiquat chloride (MP-Cl) applied at the late prebloom stage or during bloom increased the set and yield of ‘Concord’ grape (Vitis labruscana Bailey) and restricted length of pre-existing but not yet fully expanded internodes, but not those formed subsequent to treatment. Unlike most growth retardants, MP-Cl appears to exert its effect directly on the developing flowers rather than via vegetative growth control.

Open Access

Abstract

We previously reported a method for shoot tip micropropagation of the Vitis hybrid ‘Remaily Seedless’ (1, 2). In preliminary trials, rooting of subcultured shoots was erratic and shoots deteriorated after 2 weeks in culture. Herein we report the effects of sucrose and naphthaleneacetic acid (NAA) concentrations on the physical condition of subcultured shoots and subsequent root production in an attempt to increase the efficiency of grape micropropagation.

Open Access
Authors: and

Pollen from the doubled haploid peach [Prunus persica (L.) Batsch] `Hall-D' was irradiated with 0, 290, 530, 820, 1000, 5000, or 9000 Gray (Gy) of gamma radiation, 113 μW·cm-2 of ultraviolet (UV) radiation, or exposed to 100 °C for 2 h. In vitro pollen germination percentages were recorded and pollen was used to pollinate more than 10,000 emasculated or male-sterile peach flowers. Although pollen germination in vitro was stimulated by <1000 Gy of gamma irradiation, seed set following pollination was greatly reduced in all treatments. These results suggest that low levels of irradiation are sufficient to render pollen infertile while still maintaining germination capacity. Such results may be useful for pollination-induced parthenogenetic egg division for the production of maternally derived haploids and for the production of interspecific hybrids.

Free access
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Shoots were regenerated from cotyledons of mature stored seed of three peach rootstock cultivars (`Flordaguard', `Nemared', and `Medaguard'). Shoot regeneration rates were highest when cotyledons were cultured for 3 weeks in darkness on Murashige and Skoog (MS) medium with 2.5% sucrose and a combination of IBA (1.25 or 2.5 μm) and TDZ (6.25 or 12.5 μm). Regeneration rates for `Flordaguard', `Nemared', and `Nemaguard' were as high as 60%, 33%, and 6%, respectively. Length of seed storage (1 to 3 years) did not affect regeneration rates. Seventy percent of regenerated shoots produced rooted plants. This regeneration method is rapid and simple, and stored seed can be used year-round. It may be a useful regeneration system for gene transfer in seed-propagated peach rootstocks. Chemical names used: 5 indole-3-butyric acid (IBA); thidiazuron (TDZ).

Free access
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The effects of cold storage, photoperiod, and growth temperature on flowering incidence in four clones of garlic (Allium sativum L.) were studied. While flowering percentage was influenced most by clone, interactions with photoperiod, growth temperature, and storage occurred. Clone R81 flowered equally well in all conditions, whereas flowering percentage of clones D129, D130, and PI485592 was reduced by cold (4C) storage of either bulbs or plants, long (16-h) photoperiod, and at 18C relative to 10C. The highest flowering percentage in all garlic clones was achieved by growing plants at 10C under short (9- to 10-h) photoperiod with no cold storage of bulbs before planting.

Free access
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Despite its long history of obligate vegetative propagation, garlic (Allium sativum L.) exhibits a surprisingly large amount of variation between clones, as evidenced by both morphological and isozyme markers. As reported previously, several garlic clones which produce viable seed have been identified in the Wisconsin collection, and a possible correlation between clone fertility, morphology, and isozyme banding patterns was examined. The potential use of isozymes to analyze sexually-derived hybrid garlic lines, haploids, and interspecific hybridizations was also investigated.

Free access
Authors: and

Abstract

In an effort to improve grapevine micropropagation, shoot proliferation and rooting in response to explant preparation and incubation conditions were investigated. The explants were three- to four-node shoots (15 mm) of the Vitis hybrid ‘Remaily Seedless’ cultured in vitro. The factors considered were white light of diverse spectral irradiance distributions, blue light, red light, 10-hr light/14-hr dark and 16-hr light/8-hr dark photoperiods, and leaf and/or apex removal from the explant. In white light and short days, leaf and/or apex removal did not affect shoot production; however, more shoots of at least three nodes, the desired size for micropropagation, were produced when leaves were retained. Shoot production was significantly greater in blue than in red light. Differences in shoot production in white lights of various spectral irradiance distributions were attributed to differences in blue : red irradiance ratios. Shoot production was greater with ratios of 0.6 to 0.9 than with lower and higher ratios. A greater percentage of subcultured shoots rooted in long days and red light than in blue or white light. The number of roots produced per shoot, and total root length, were also greater in red light.

Open Access
Authors: and

Because of the sensitive nature of the RAPD-PCR procedure, it has often been difficult to assess the inheritance of RAPD markers for mapping or genetic distance studies. Genetic analysis of RAPDs can be further complicated by the fact that markers are transmitted in a dominant fashion. Using six doubled haploid and therefore completely homozygous peach parental lines and seven F1 populations resulting from crosses of these parents, we found that some RAPD markers did not follow expected inheritance patterns. Specifically, bands present in parents were not transmitted to the progeny. This phenomenon occurred in approximately 5% of the parent/progeny and primers tested. Although it is not clear whether these patterns are the result of as yet unexplained maternal or somatic effects in the peach or artifacts of the RAPD-PCR process, these results indicate that RAPD markers should be used cautiously in peach mapping and genetic diversity studies.

Free access

Abstract

Thermal and differential thermal analysis (DTA) are used to detect exotherms that result from the freezing of supercooled tissues (4). They provide a convenient and rapid means of assessing the hardiness of tissues that supercool, such as the floral primordia of Prunus spp. (3) and the compound buds of Vitis spp. (2). The inability to process a large number of tissue samples simultaneously, however, has been a major limitation of DTA. Ashworth et al. (3) described a computer-assisted data-logging system for recording thermal analysis data generated when Prunus flower buds were frozen. Multiple cooper-constantan thermocouples were used to increase the number of buds monitored on a given channel of a multichannel data-logger. Copper-constantan thermocouples, however, were not adequate with our instrumentation to discriminate exotherms generated by the freezing of individual shoot primordia of compound grapevine buds. Furthermore, anatomical barriers to ice propagation may be negated if thermocouples are inserted into buds to increase exotherm detection (5).

Open Access