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Mohamed F. Mohamed, Dermot P. Coyne and Paul E. Read

Plant regeneration has been achieved in two common bean lines from pedicel-derived callus that was separated from the explant and maintained through successive subcultures. Callus was induced either on B5 or MS medium containing 2% sucrose and enriched with 0.5 or 1.0 mg thidiaznron/liter alone or plus various concentrations of indoleacetic acid. The presence of 0.07 or 0.14 g ascorbic acid/liter in the maintenance media prolonged the maintenance time. Up to 40 shoot primordia were observed in 4-week-old cultures obtained from 40 to 50 mg callus tissues on shoot-induction medium containing 1-mg benzyladenine/liter. These shoot primordia developed two to five excisable shoots (>0.5 cm) on medium with 0.1-mg BA/liter. A histological study confirmed the organogenic nature of regeneration from the callus tissues. The R2 line from a selected variant plant showed stable expression of increased plant height and earlier maturity. Chemical names used: ascorbic acid, N- (phenylmethyl)-1H-pnrin-6-amine [benzyl-adenine, BA], 1H-indole-3-acetic acid (IAA), N- phenyl-N'-1,2,3-thiadiazol-5-ylurea [thidiazuron, TDZ].

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Thomas O. Athoo, Andreas Winkler and Moritz Knoche

The pedicel of a sweet cherry fruit is a useful indicator of its postharvest freshness ( Drake and Elfving, 2002 ; Sekse, 1996 ; Wani et al., 2014 ). Shriveled and brown pedicels are indicative of inadequate storage conditions, or a too long

Open access

Tong Geon Lee, Reza Shekasteband, Naama Menda, Lukas A. Mueller and Samuel F. Hutton

. Tomato inflorescences typically have an abscission zone (joint) in the pedicel of each flower. Detachment of the fruit at this joint at harvest results in the calyx and stem remaining attached to the fruit, which can in turn puncture or otherwise damage

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Mengzi Zhang, Jie Yang, Huitang Pan and Brian J. Pearson

substrate surface level. Pedicel length and flower size were measured on three randomly selected individual mature flowers on the first floral whorl on primary inflorescences. Old leaf and new leaf, defined as mature leaf before and after PGR treatment

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Della Carbonaro and William B. Miller

Success in the production of seasonal flowering plants requires adequate knowledge of plant growth patterns and rates. In Easter lilies, pedicel growth is one the components of final plant height. Flower bud growth rates are important from the standpoint of timing of anthesis. To learn more about the localization of growth in Easter lily flower buds and pedicels, we conducted a time course experiment. Buds and pedicels were marked at 1.2 mm intervals using an inked bolt. Distances between ink marks were determined at 3 day intervals. Results indicate that 30 mm flower buds elongate almost exclusively from basal regions of the bud. The basal 1.2 mm segment elongated 16 mm in 20 days, while the apical 1.2 mm segment elongated 0.75 mm in the same period. Larger buds (initially 90 mm) gave similar results, although bud tip growth rate increased to some degree just prior to flowering. Pedicel elongation occurred almost exclusively at the apical end of the pedicel, adjacent to the region of greatest bud growth.

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Ridwan Setiamihardja and Dean E. Knavei

Genetic correlations for pedicel length and diameter, fruit length and diameter, and fruit detachment force (FDF) were determined in three pepper (Capsicum annuum L.) families from crosses of `Serrano Chili' (low FDF) with three cultivars (`Anaheim Chili', `Keystone Resistant Giant', and `Red Cherry Small') characterized by high FDF and different fruit characteristics. Pedicel and fruit length means of F1 generations were nearly intermediate, while pedicel and fruit diameter means were shifted toward `Serrano Chili'. Progeny distributions in F2 generations were continuous and F2 means slightly less than the F1 means. Generation mean analyses indicated gene effects for pedicel and fruit length to be mostly additive. Gene effects for pedicel and fruit diameter were also mostly additive. Pedicel length was positively correlated genetically with fruit length, and pedicel diameter was positively correlated with fruit diameter. FDF means were positively correlated with pedicel and fruit length and diameter in most segregating generations. In BCP2 (`Serrano Chili' × `Red Cherry Small'), FDF was negatively correlated with pedicel and fruit length. Pendant fruit in BCP2 (`Serrano Chili' × `Red Cherry Small') were longer and narrower than upright fruit and FDF decreased with increased length of both pedicel and fruit.

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N. Georgelis, J.W. Scott and E.A. Baldwin

Small-fruited cherry tomato accession PI 270248 (Lycopersicon esculentum Mill. var. cerasiforme Dunal) with high fruit sugars was crossed to large-fruited inbred line Fla.7833-1-1-1 (7833) that had normal (low) fruit sugar. Sugars in the F2 were positively correlated with soluble solids, glucose, fructose, pH, and titratable acidity, and inversely correlated with fruit size. Earliness was not significantly correlated with sugars but was negatively correlated with fruit size. Thus, the lack of a sugar-earliness correlation indirectly indicates a trend for early tomato plants to be lower in sugars than later maturing plants. Sugars were not correlated with yield or pedicel type. Fruit from indeterminate plants had significantly more sugars than from determinate plants. Six random amplified polymorphic DNA (RAPD) markers linked to high sugars were found, five dominant (OPAE 4, UBC 731, UBC 744, UBC 489, UBC 290) and one co-dominant (UBC 269). Five of the markers were also linked to small fruit size and one of these also was linked to low yield (UBC 290). The sixth marker (UBC 269) was linked to indeterminate plant habit. UBC 731, UBC 489, and possibly OPAE 4 were in one linkage group, while UBC 744 and UBC 290 were in another linkage group. Combinations of all the markers together explained 35% of the sugar variation in the F2 grown in Spring 2002.

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Ahmed M. Akl, Abdel-Fattah M. Eid and Mohamed Y. Hegab

This part of the investigation studied the effect of foliar spraying with urea (0.5%); a mixture of Zn (0.4%), Mn (0.3%), Fe (0.5%), and Cu (0.3%) in sulphates (from 23% Zn, 28% Mn, 19% Fe, and 30% Cu, respectively); and two growth regulators (GA3 at 25 ppm and α-NAA at 10 ppm); as well as number and date of sprays on fruit pedicel pectin content, some flowering aspects, and fruit set and drop percentages. Applying urea, micronutrients, or both significantly increased pectin content in the pedicels of the attached and dropped fruit. The treatment including urea plus micronutrients resulted in the highest values for pectin in fruit stem. Either GA3 or NAA significantly raised pectin content over that of the water-sprayed control. However, NAA was more effective in increasing pectin content in fruit pedicel. The overall treatment including urea and micronutrients with GA3 or NAA was the most effective in producing the highest percentage of leafy inflorescence in 1991–92 and 1992–93 seasons. Any nutrition treatment was significantly effective in increasing fruit set and reducing fruit drop compared with the water-sprayed control; however, the treatment including all sprayed nutrients was the most effective. Application of GA3 or NAA significantly increased fruit set percentage and reduced June and preharvest fruit drop; however, NAA was more effective in reducing fruit drop than GA3.

Free access

Lingxia Sun, Sunchung Park, Martin Bukovac and Steven van Nocker

Abscission of leaves, floral organs, and fruit is a developmentally and environmentally regulated process initiated in specialized thin layers of cells within abscission zones (AZs). Very little is known about early molecular events that drive abscission, especially of fruit. Commercial apple production relies on the use of flower and fruit abscission-promoting and -inhibiting compounds to enhance fruit quality, control preharvest fruit drop, and maintain consistent annual bearing. The success of chemical treatments is strongly influenced by numerous factors, including environment, genotype, developmental stage of the fruit, and physiological state of the tree. Toward developing improved strategies for regulating fruit abscission, we carried out transcriptional profiling of competent-quiescent and activated abscission layers. We found that a decisive event in the sequential process of abscission layer development is the transcriptional activation of the MdPEL1 gene, encoding a plant pectate lyase protein and potentially involved in the degradation of the middle lamella of adjacent abscission layer cells. Additionally, regulatory elements of at least 12 homologous pectate lyase genes in Arabidopsis thaliana were found to direct expression in floral AZs and in dehiscence zones along valve margins, suggesting that these genes have evolutionary conserved function. This work identifies a novel role for pectate lyases in plants. Furthermore, many abscission-related genes identified in this study are being used to track biochemical and regulatory pathways that participate in abscission in response to chemical treatments or environmental effects.