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Open access

Christopher S. Walsh, Harry J. Swartz, and Louis J. Edgerton

Abstract

Ethylene evolution in excised apple (Malus domestica Borkh.) spurs was measured following the application of thinning treatments. Within 1 day (20 hours) of application, ethylene evolution by spurs of ‘Golden Delicious’ trees treated with 15 ppm napthaleneacetic acid (NAA) and 100 ppm (2-chloroethyl)phosphonic acid (ethephon) was 5 times greater than in control spurs, and those treated with 200 ppm ethephon evolved seven times more. Less fruit thinning occurred in response to the application of 100 ppm ethephon than 15 ppm NAA. Increased ethylene evolution was also detected in attached ‘Spatbluhender’ fruitlets 8 hours after NAA treatment.

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Jean-Marc G. Guedon* and James McConnell

Elaeocarpus yoga Merr. (Tiliaceae) is an attractive tree indigenous to the Mariana Islands and Palau. Recently its population has declined due to deforestation, typhoon damage, and pest problems. Stem cuttings of E. yoga were taken from hardwood, semihardwood, or softwood and treated with acid or salt forms of indole-3-butyric acid (IBA) or napthaleneacetic acid (NAA) at several concentrations. The cuttings were treated with on of the following: acid form at 0.5 mL·L-1 IBA + 0.25 mL·L-1 NAA; 1 mL·L-1 IBA + 0.5 mL·L-1 NAA, 2 mL·L-1 IBA + 1 mL·L-1 NAA; salt form at 1, 3, and 8 g·kg-1 IBA/. Rooting after 8 weeks was compared among treatments. The salt form of the IBA treatment at 3 g·kg-1 produced the greatest rooting percentage, root number and length. The acid form containing both IBA and NAA produced the smallest average rooting percentage.

Free access

Michelle Carratu and Roger J. Sauve

Several studies were conducted to evaluate the effects of cultivar, cutting length, and leaf number on rooting of poinsettia. Cuttings were rooted under mist in a soilless medium with 50 cuttings per treatment. Visual rootball ratings were performed after 3 wk. In the first experiment, rooting of ten poinsettia cultivars was compared. The rooting hormone was 0.1% indole-3-butyric acid (IBA). Rooting of `V-14 Red' and `V-14 Marble' was the highest. `V-17 Pink' and `V-17 Marble' had the highest number of callused cuttings. `V-17 White' produced the highest number of extensively rooted cuttings. `V-14 Pink' (3-lf) cuttings 12 cm long rooted better than 5 cm cuttings. Rooting of (7 cm) 3- and 4-leaf cuttings was higher than rooting of 2-leaf cuttings. `V-14 Pink' cuttings treated with 0.8% IBA or 1% IBA + 0.5% 1-napthaleneacetic acid (NAA) rooted better than with 0.1% or 0.3% IBA.

Free access

Paula P. Chee

Plant regeneration from tissue cultures of summer squash (Cucurbita pepo L. ev. YC60) has been observed. Embryogenic callus tissues were initiated when cotyledons of mature seeds were excised and cultured on Murashige and Skoog (MS) medium supplemented with either 22.7 μm 2,4-D or a combination of 4.7 μm 2,4,5-T, 4 μm BA, and 0.5 μm kinetin. Clusters of somatic embryos were found in callus tissue. Maturation of these somatic embryos was effected by transfer of embryogenic callus tissues to MS supplemented with 0.5 μm NAA and 0.25 μm kinetin. Regenerated mature plants were morphologically normal and set fruits containing seeds that germinated normally. Chemical names used: 6-benzylaminopurine (BA); 2,4-dichlorophenoxyacetic acid (2,4-D); α - napthaleneacetic acid (NAA); 2,4,5-trichlorophenoxyacetic acid (2,4,5-T).

Open access

William R. Krul and Joseph F. Worley

Abstract

Callus tissue of ‘Seyval’ (Seyve-Villard 5-276) (Vitis sp.), a French hybrid grape, formed adventitious embryos when transferred from a medium with 2,4-dichlorophenoxyacetic acid (2,4-D) to a medium containing 1-napthaleneacetic acid (NAA). Embryos began to turn green and develop into apparently normal vines when placed on a medium free of hormones and vitamins in the light. Histological evidence indicated that plants derived from callus originated from embryo-like structures and not from plantlets or excised buds. Secondary embryoids formed on primary embryoids, and tertiary embryoids occasionally formed on secondary embryoids. More than 50 vines and several hundred adventitious embryoids were obtained from approximately one cubic centimeter of callus.

Open access

Lani R. Ikeda and Michael J. Tanabe

Abstract

Leafy aerial pseudostems and decapitated crown sections from in vitro plantlets of ginger (Zingiber officinale Roscoe) were cultured in nutrient medium containing Murashige and Skoog salts, vitamins, sucrose, and various concentrations of BA and NAA. Pseudostems cultured on solid medium supplemented with 11 μM BA in combination with 0.6 μM NAA produced an average of five shoots and 15.3 roots. Decapitated crown sections cultured in liquid medium with 11 μM BA produced an average of 10 shoots and 16.3 roots. These subculture techniques could significantly contribute toward maximizing the use of high-quality rhizomes for in vitro propagation of edible ginger plantlets. Chemicals names used: 1-napthaleneacetic acid (NAA), N-(phenyl-methyl)-1H-purin-6-amine (BA).

Open access

David G. Himelrick, James E. Pollard, and G. O. Estes

Abstract

Leaves from succinic acid-2,2-dimethylhydrazide (daminozide)-treated seedlings of ‘McIntosh’ apple (Malus domestica Borkh) accumulated significantly more 45Ca than those from 1-napthaleneacetic acid (NAA)-treated seedlings. Stem sections from daminozide-treated seedlings accumulated significantly more 45Ca than stems from control seedlings. Total 45Ca content in daminozide-treated seedlings was significantly greater than in either controls or NAA-treated seedlings. The expected reduction in total shoot length by treatment with daminozide, NAA + daminozide and NAA was noted. The increases in 45Ca content in all treatments appear to be due in part to the concentration effect of reduced shoot growth and in part to an effect of daminozide on rate of uptake.

Open access

J. L. Johnson and E. R. Emino

Abstract

In vitro propagation of Mammillaria elongata DC plants was successful using tubercle explants grown on a medium based on Murashige and Skoog’s high salts supplemented with various auxins and cytokinins. Optimum callus proliferation occured in response to 2,4-dichlor-ophenoxyacetic acid (2,4-D) (2-10 mg/liter) with either kinetin or 6-(dimethylallylamino)-purine (2iP) (1-2 mg/liter). Root initiation was optimized with either napthaleneacetic acid (NAA) or indolebutyric acid (IBA) (60 mg/liter). Shoot initiation was optimized by addition of 2iP (10 mg/liter) and indoleacetic acid (IAA) (1 mg/liter). The auxin:cytokinin balance required for shoot initiation appears to be unique for each species of Mammillaria studied. Shoots developed in vitro of M. elongata were successfully transferred to greenhouse conditions, where they rooted and continued to grow.

Free access

Robert L. Geneve, Wesley P. Hackett, and Bert T. Swanson

Exogenous ethylene could not substitute for NAA to induce adventitious root initiation in juvenile petiole explants of English ivy (Hedera helix L.), indicating that the action of auxin-stimulated root initiation was not directly mediated through ethylene production. Mature petioles did not initiate roots under any auxin or ethylene treatment combination. Ethephon or ACC supplied at 50 or 100 μm was inhibitory to NAA-induced root initiation in juvenile petioles. The pattern of ethylene production stimulated by NAA application was significantly different in juvenile and mature petioles. Ethylene evolution by juvenile petioles declined to near control levels during from 6 to 12 days after NAA application. Reduction in ethylene production was due to reduced availability of ACC in juvenile petioles. Mature petioles continued to produce ethylene at elevated levels throughout the course of the experiment. Ethylene does not appear to play a significant role in the differential root initiation response of juvenile and mature petioles treated with NAA. However, ethylene appeared to have an inhibitory effect during root elongation stages of adventitious root development in juvenile petioles. Chemical names used: 1-aminocyclopropane-1-carboxylic acid (ACC); 1-napthaleneacetic acid (NAA); 2-chloroethylphosphonic acid (ethephon).

Free access

Mushtaq Sarwar and Robert M. Skirvin

Adventitious shoots were regenerated from apple (`Wijcik', `McIntosh', `Macspur', `M-26' and `Mutsu') by excising leaves from in vitro-grown shoots, cutting them into three sections, and plating them onto regeneration media. Cultures were kept in the dark for 1 to 4 weeks and then moved to light for further shoot development. MS medium supplemented with thiadiazuron (2-3 μM) and napthaleneacetic acid (5 μM) produced the highest number of shoots per leaf segment. `Wijcik' and `M-26' regenerated best from big leaves, whereas `McIntosh' and `Macspur' regenerated best from small leaves. Shoot formation was enhanced by 3 to 4 weeks of dark treatment and by placing the leaf on medium with its abaxial surface uppermost. The cut surface of leaf segments produced the most regeneration sites. In vitro adventitious shoots were transferred to various concentrations of BA (5, 10, 15, 20, 25 and 30 μM to screen them for BA tolerance and to predict their adult growth habit. These shoots will be rooted and transferred to greenhouse and field conditions for long-term evaluations.