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  • Author or Editor: Harry Swartz x
  • Journal of the American Society for Horticultural Science x
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Abstract

Vigor, petiole length, stand, runner production, yield per square meter of matted row, and numbers of trusses per crown were greater in tissue culture-produced plants when compared to runner plants of strawberry (Fragaria × ananassa Duch). Leaf area and shape, number of serrations per leaflet, petiole pubescence density, flowers per truss, yield per crown, harvest time, small fruit weight, and percent imperfect fruits did not vary appreciably between propagation methods. Size of large fruit and mean fruit weight were less in tissue culture-produced plants. All changes in performance were caused, at least in part, by the increased vigor and axillary bud activity of tissue culture-produced plants. Tissue culture propagation of strawberry is particularly adapted to production of planting stock for nurseries because 60% more runner plants are produced from tissue culture plants. Production of variant plants from tissue culture was largely limited to 1 meristem-tip line. For certain cultivars, some adjustment of nursery inspection procedures for off-type plants will be required.

Open Access

Abstract

Open-pollinated species, interspecific hybrid seedling populations, and selected clones propagated by softwood cuttings and tissue culture were used to further evaluate the use of dry soil to screen blueberry seedlings for drought resistance. These different propagation types of Vaccinium (subgenus Cyanococcus) were screened for drought resistance in a Galestown fine sandy loam soil. The soil was permitted to dry to progressively higher soil tension levels to a maximum of 0.8 MPa. The plants were evaluated by scoring them on a 1 to 9 shoot damage rating scale and by determining the fraction of total biomass partitioned as roots. Drought resistance in blueberries is heritable and there is a high degree of genetic diversity within and among Vaccinium spp. for resistance to water deficits. Southern species (Vaccinium darrowi Camp, V. elliottii Chapman, and V. ashei Reade) were more drought-resistant than northern species (V. corymbosum L., V. vacillans Torrey, and V. myrtilloides Michaux), which demonstrated the reliability of this soil screening method. Clones with half their germplasm from southern species were usually drought-resistant. This screening method can be used to select for shoot and root vigor and drought resistance in 6- to 7-month-old blueberry seedlings.

Open Access

Abstract

Comparative field performance of thornless blackberry plants produced by tissue-culture (TC) and standard (ST) methods (tip layers or stem cuttings) was studied to determine any effect of TC propagation on clonal phenotypic stability. In general, TC plants performed as well as, and were phenotypically similar to, ST plants. Some differences in leaf size and pattern were observed; however, the differences were related to the increased vigor of TC plants of these cultivars. Total growth of TC and ST plants of ‘Black Satin’, ‘Hull Thornless’, ‘Thornfree’, and SI-US 68-6-17 was similar. ST plants of ‘Dirksen Thornless’ and ‘Smoothstem’ failed to grow as rapidly as TC plants of these cultivars or ST plants of the other cultivars, resulting in significantly reduced 2nd-year yields. First-year growth of all TC plants was more uniform than corresponding ST plants. On the average, fruit size was smaller on TC plants; however, this was true in both years only for ‘Black Satin’. The response varied for other cultivars with TC plants of ‘Dirksen Thornless’ actually having larger fruits in one year. No consistent differences in bloom date or median harvest date due to propagation method were observed. No variant plants were observed in the field; however, one sectorial leaf chlorotic variant was observed after TC propagation but prior to field planting.

Open Access

The net carbon exchange rate (NCER) of Fragaria species, synthetic octoploids [SO (interspecific hybrids)], F1 (SO × cultivar), and first outcross [OC1 (F1 × cultivar)] hybrids were evaluated in both field and greenhouse conditions. Plants were grown in a field trial at the Elora Research Station in Ontario, Canada, for one season and then plants were dug and moved into a greenhouse where the trial was repeated during the next season. Single leaf photosynthesis measurements and light response curves were generated at different stages of plant development. Photosynthetic capacity of the species was related to the ecological background of the species with sun-adapted species having higher rates compared with the shade-adapted species. The Fragaria species and introgressed hybrids (F1 and OC1) had significantly higher NCERs compared with the cultivars with rates 28% and 23% higher, respectively. Species and hybrids also appear to have increased adaptability to both high and low light conditions. These increases in NCER may be a heterotic effect because NCER of the hybrids were consistently higher compared with the midparent values and in some cases, they were higher than the high parent. These results suggest that the introgression of lower-ploidy Fragaria species into the cultivated strawberry (Fragaria ×ananassa) may lead to increased NCER and light adaptability.

Free access

Abstract

A phenotypic and sexual analysis of Fragaria vesca ‘Albo-Marginata’ determined that the leaf variegation was of chimeral origin. Stable periclinal chimeras were established in vitro from runner tips. Plants were transferred to proliferation media containing 0.5 μm IBA, 0.3 μm GA3, and BA at either 0, 1.3, 4.4, or 13.2 μm. Whereas the histogens of field-grown runner plants remained stable, more than 90% of the plantlets propagated in vitro varied from the original explants. Most variants were albino or were green, but some were mericlinal chimeras. Histological evidence indicated that many shoots were adventitious, arising from basal callus tissue or petioles. Chemical names used: 1H-indole-3-butanoic acid (IBA); gibberellic acid (GA3); N-(phenylmethyl)-1H-purin-6-amine (BA).

Open Access

Abstract

Removal of bud scales hastened bud burst of several early and late blooming apple cultivars. Descaling was most effective during the onset and end of rest. During deep rest, bud scale removal was effective only when applied 2 weeks before forcing conditions. Extracts of bud scales inhibited apple bud break in vitro. Abscisic acid (ABA) may have been responsible for part or all of this bioactivity, since ABA occurred in bud scale diffusates and could replace or reinforce the bud scales in vitro. Wound-produced ethylene was not involved in the bud scale removal response.

Open Access