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  • Author or Editor: Ronald G. Goldy x
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Four muscadine grape (Vitis rotundifolia Michx.) cultivars (Carlos, Noble, Regale, and Tarheel) were evaluated for their ability to be cultured in vitro. Axillary buds were placed on Murashige and Skoog medium as modified by Chee. Different levels of benzylaminopurine [(BA) 0.5 to 10.0 μm], kinetin [(KIN) 0.5 to 5.0 μm], and thidiazuron [(TDZ) 0.5 to 11.3 μm], and different explant positions were evaluated for their effect on in vitro explant establishment and shoot production. Thidiazuron (2.3 to 4.5 μm) alone or in combination with BA (1.0 to 5.0 μm) or KIN (1.0 or 5.0 μm) was effective for establishing axillary buds. Similar levels were also effective for promoting shoot proliferation. Explants originating from the 10 basal nodes of a shoot with at least 25 nodes gave better shoot proliferation than explants originating from the 10 distal nodes. Chemical names used: 6-benzylaminopurine, 6-furfurylaminopu. rine (kinetin):N -phenyl-N'-l,2,3 -thiadiazol-5-y lurea (thidiazuron).

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Flower buds of blackberries, blueberries, grapes, raspberries, and strawberries were observed in order to determine the relationship of morphological development and meiosis. Blueberries showed the least development whereas grapes and brambles had considerable development prior to meiosis. Meiotic figures were found with relative ease in blueberries, strawberries, and grapes but with difficulty in brambles.

Open Access

Field studies were conducted in 2003 and 2004 to determine effects of withholding irrigation on pepper (Capsicum annuum) plant height, leaf chlorophyll content, yield, and irrigation water use efficiency. Irrigation treatments were initiated at pepper transplanting (S0), after transplant establishment (S1), at first flower (S2), at first fruit (S3), or at fruit ripening (S4). The control treatment received only enough water to apply fertigation (FT). Withholding irrigation did not affect pepper plant height except FT treatment, but increased leaf chlorophyll content. Withholding irrigation until S4 saved 50% and 41% of irrigation water in 2003 and 2004, respectively, without affecting fruit yield compared with the treatment where irrigation started at transplanting. However, yield in the FT treatment was significantly reduced. Irrigation water use efficiency (pepper yield per unit area per millimeter of water applied) was maximum at S4 (59.1 kg·ha−1 per millimeter) and S3 (24.1 kg·ha−1 per millimeter) in 2003 and 2004, respectively. Similar trends in response of pepper to the irrigation treatments were observed in 2003 and 2004 even though there were large differences in rainfall, and pepper yield between years. This suggests that withholding irrigation until first fruit may help to maintain pepper yield while reducing irrigation costs. However, it is important to have adequate soil moisture at transplanting to insure adequate transplant establishment.

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Three pentaploids produced from hybridizing hexaploid Vaccinium ashei Reade and diploid V. darrowi Camp were analyzed for fruit set, number of seeds/fruit, seedlings/pollination, pollen grains/sporad, 2n gamete production, pollen germination, leaf area and berry weight, color, scar, and firmness. The pentaploids were intermediate between the parental species in fruit size and leaf area. There was high variation in fertility and in fruit quality among the pentaploid hybrids.

Open Access

Abstract

Methods of producing 8x plants from 4x V. corymbosum clones through in vitro colchicine treatments were investigated. Colchicine concentrations and exposure times ranged from 0.001% to 0.2% and 1 to 14 days, respectively. Pretreatments designed to predispose the plants to the effect of colchicine also were investigated. Eleven 8x plants and one 4x-8x chimera were selected from pretreated plants exposed to 0.025% or 0.05% colchicine. The superior treatment was 0.025% with a 24- or 48-hr exposure time in liquid medium. No differences were noted between warm/dark and cold/dark pretreatments. No differences were observed among 24-, 48-, 96-, and 192-hr growth intervals between cold pretreatment and colchicine treatment. However, a significant genotype effect in response to colchicine was found, both with respect to culture survival and polyploid induction.

Open Access

Abstract

Pollen morphology of 10 Vaccinium species, 10 interspecific hybrids, and 3 colchicine-induced polyploids were studied using scanning electron microscopy. Size, exine patterning, furrow and pore size and shape, and general appearance were investigated. Although differing morphological features were generally lacking, some interspecific differences and variation within hybrid populations were noted. Furrow and pore sizes, and the associating opericuli were the most valuable characters. Some species had large furrows with large rounded pores and others had small furrows with insignificant pores. Exine patterning was minimal and, when present, generally occurred in the inter-colporate regions. F1 populations of V. corymbosum × V. elliottii had the greatest exine variation and the degree of exine patterning revealed a possible dosage effect. Exine patterns suggest that the ancestors of V. myrsinites may be V. darrowi and V. elliottii rather than V. darrowi and V. tenellum as previously proposed by Camp.

Open Access

Abstract

Four isozyme systems, glucosephosphate isomerase (PGI, EC 5.3.1.9), phosphoglucomutase (PGM, EC 2.7.5.1), isocitrate dehydrogenase (IDH, EC 1.1.1.42), and malate dehydrogenase (MDH, EC 1.1.1.37), were identified as useful in detecting intergeneric Vitis vinifera × Muscadinia rotundifolia hybrids. Polymorphism between and within the two genera was observed at the PGI-2, PGM-2, and IDH-1 loci. However, the two appeared fixed for different alleles at the MDH-3 locus. The combination of any two of the enzyme systems allowed for rapid identification of F1 hybrids at the young, pre-fruiting seedling stage.

Open Access