Chimeral `Thornless Evergreen' (CTE), (Rubus laciniatus Willd.) somaclones selected in 1983 and field planted in 1985 were reexamined in 1992 for various vegetative and reproductive characteristics. Two major types of thornless (prickle-free) plants, intermediate-sized (`UI 6-6' = `Everthornless') and dwarf (`UI 6-4'), originally selected from a chimeral thornless parent plant, were compared with thorny plants. The intermediate and dwarf somaclones have maintained their distinctive habits over 7 years' growth in the field, indicating that their growth habits are stable and not a transient effect of tissue culture. Although the thornless somaclones remained thornless, the degree and type of prickle-like structures varies considerably, indicating that the thornless gene (Ste) does not entirely suppress the production of prickles, but apparently alters their development. Increasing suppression was directly related to increasing dwarfism, suggesting a link between thornlessness and internode length.
A method has been developed for micropropagation of the difficult-to-root winegrape cultivar `Norton' (Vitis aestivalis). Plants were established in vitro from axillary bud cuttings of field-grown plants. Four levels of 6-benzylaminopurine (BA) and three levels of naphthaleneacetic acid (NAA) were tested in a factorial arrangement for their effectiveness in promoting multiplication of shoots from single-node explants. Three levels of NAA and two concentrations of Murashige and Skoog (MS) basal medium were tested for their effectiveness in promoting rooting of shoot tips. The greatest number of shoots per axillary bud in combination with the greatest shoot length were produced with 4 μmol·L-1 [0.90 mg·L-1 (ppm)] BA. NAA had no effect on shoot multiplication. NAA was not required for in vitro rooting. All rooted plants survived the transition to soil.
In vitro techniques were developed to regenerate plantlets (calliclones) from callus of scented geraniums (Pelargonium spp.). Calliclones were compared to plants derived from stem, root, and petiole cuttings of 5 cultivars. Plants from stem cuttings of all cultivars were uniform and identical to the parental clone. Plants from root and petiole cuttings were more variable with the amount of variation dependent upon cultivar. High variability was associated with calliclones. Aberrant types included changes in plant and organ size, leaf and flower morphology, essential oil constituents, fasciation, pubesence, and anthocyanin pigmentation. Calliclone variation was dependent upon clone and age of callus. Variability in calliclones was due to segregation of chimeral tissue, euploid changes, and heritable changes which may involve individual chromosomal aberrations or simple gene mutations. Variability of calliclones might be exploited for improvement of vegetatively propagated crops especially highly polyploid, sterile lines.
Extensive root development was observed on Stage 2 `Red Emerald' philodendron shoots grown on standard multiplication medium consisting of Murashige and Skoog salts and vitamins with 6-benzylaminopurine (BA, 0.2 mg·liter-1. Root development was suppressed significantly when the level of NH4NO3 was doubled from standard levels (lx, 1650 mg·liter-1) to 3300 mg·liter-1 (2×). A higher level of NH4NO3 (3×, 4950 mg·liter-1) was detrimental to shoot growth and proliferation. This information may be useful for commercial propagators who wish to suppress root development at the shoot multiplication stage.
Acclimatization and growth of in vitro-derived apple shoots of two apple scion apple cultivars were compared under fogged conditions in a greenhouse and in a commercial growth cabinet (Phototron). Plant survival rates of microcuttings of `Royal Gala' and `Jonagold' were significantly better when maintained in the Phototron units than when grown in a greenhouse under fog. The number and length of roots on microcuttings was significantly higher in the Phototron than under fog. In the present study, we demonstrated that the Phototron environment was better than a fogged greenhouse for establishing apple shoots ex vitro. However, the Phototron units are so small that they hold no more than 100 to 120 plants at a time. Therefore, the units will be of most value to growers or individuals in laboratories who do not have a constant need for acclimatization facilities. Growers who acclimatize many plants should continue to use fogging or misting facilities.
Shoot proliferation of ‘Forever Yours’ greenhouse rose (Rosa hybrida L.) was a-chieved in vitro using a modified Murashige and Skoog (MS) high salt medium supplemented with 6-benzylamino purine (BA) at 2.0 mg/liter and naphthaleneacetic acid (NAA) at 0.1 mg/liter. Shoots were readily rooted on ¼ strength MS medium without hormones. Rooted shoots were successfully transferred to soil and grew well in the greenhouse.
Although strawberry species have existed for an estimated 50 million years (17), and their use by man has been dated to the bronze age (19), only after the 14th century A.D. were strawberry plants gathered from the wild and grown in gardens. These first cultivated strawberry plants were grown for both ornamental and medicinal purposes (11). The strawberries of the past were different from those of today. The fruit was small, plants were not productive, and in many respects were far inferior to the large fruited cultivars that are now grown in many parts of the world.
Blackberry (Rubus sp.) fruit can be enjoyed fresh or as one of many processed products. Blackberry preserves, jam, and jelly long have been favorites in this country. Fresh blackberries generally are soft, highly perishable fruit; hence, most processing for commercial production is quick, in plants located near major production areas. Commercial blackberry production is centered in regions where native or introduced Rubus species flourish. Production trends in these regions will be described, followed by a discussion of blackberry products.
Uneven-ripening ‘Concord’ grapes were treated with 250 ppm gibberellic acid (GA3) about 2 weeks prior to harvest. “Green” berries responded with increased rate of ripening over untreated “green” berries as measured by soluble solids and anthocyanin content. GA3-treated berries also developed a callus-like layer between the pedicel and the skin which delayed drop also resulting in more evenly ripened clusters. In uneven-ripening clusters, “green” in contrast to “colored” berries had significantly fewer seeds and many of these seeds had aborted.