Search Results

You are looking at 41 - 50 of 71 items for

  • Author or Editor: Paul E. Read x
Clear All Modify Search

Terroir embodies a defined place, integrating soils, geology, climate, the cultivar, and the role of cultivation, culture, and history in producing wine (Wilson, 1999; White, 2003).The understated topographic changes, thick loess soils, diffuse climatic boundaries (humid to arid), and brief viticultural history contribute to a misconception that “terroir” may not be applicable or that niche microclimates for vineyards may not exist in Nebraska. With many new cultivars and selections now available that are adapted to growing environments once considered marginal vineyard settings and the wealth of geospatial resource databases (soils, climate, and topography) available, we have begun to combine traditional field cultivar evaluation studies with the geophysical data to determine appropriate site/cultivar suitability. Our data have shown that cultivars that were previously considered unlikely to be successful may be suited to viticulture in specific locations, e.g., Riesling, Lemberger, Cynthiana/Norton, Vignoles, and Chambourcin in southeast Nebraska (our “vinifera triangle”). Mean hardiness ratings (scale 1 to 9, where 1 = dead and 9 = no injury) have been obtained for more than 50 cultivars and selections, ranging from 1.86 for Viognier to 8.66 for Frontenac and 8.71 for Saint Croix, for example. Data for most of the cultivars under test will be presented and matched with “terroirs”, providing growers with a vineyard decision support system that can help match genotypes to their specific vineyard sites and help avoid poor cultivar selection.

Free access

RAPD and phenotypic analysis were conducted to assess clonal stability of hazelnuts generated from axillary buds cultured in vitro for long-term. The nuts produced on in vitro-propagated plants were indistinguishable from those of donor plants. With the exception of rare horizontal (plagiotropic) growth, all in vitro-propagated plants exhibited phenotypes similar to those of donor plants. RAPD analysis did not reveal any somaclonal variation between donor plants from which in vitro cultures were initiated and micropropagated plants (6-year cultures), and no somaclonal variation was detected among in vitro-propagated plants. However, polymorphism (15.6%) was detected between the parent plant and its in vitro-propagated progenies (from seedlings). These results show a good discriminatory power of RAPD to detect polymorphism between samples where it is expected, and it can be effectively used for genetic assessment of micropropagated hazelnut. No evidence of genetic or epigenetic changes was observed in long-term cultured hazelnut, and thus long-term in vitro culture of hazelnut does not seem to limit its clonal propagation.

Free access

Rosemary Rosmarinus officinalis is a member of the Lamiaceae. Rosmarinic acid (RA) is a very strong antioxidant produced in the chloroplast, and used to protect plant tissues against oxidative stress. A number of investigations showed that the sucrose concentration in the callus growing medium greatly influenced the production of secondary metabolites of the phenylpropanoid pathway such as RA. The aim of this study was to test the effect of elevated sucrose concentrations (2%, 3%, 4%, 5%, and 6% sucrose) and the effect of light and dark treatments on the production of RA in the callus of five different genotypes. The genotypes were Majorca, Rosmarinus officinalis, Pine Scented, Madeline Hill, and APR. It was found that the dark treatment produces more RA than the light treatment in all genotypes, and in all sucrose concentrations. The RA concentration increased with increasing the sucrose concentration from 2%—reaching the highest concentration at 4% and 5% in most genotypes. The RA concentration declined again at 6% sucrose in all genotypes. We concluded that for the extraction of RA from rosemary callus it is preferred to be produced in the dark—this will save energy and will produce more RA than the light treatment. Also it is preferred to use sucrose concentration at 4% for genotypes Rosmarinus officinalis, Pine Scented, and APR; and 3% sucrose for genotype Madeline Hill in the dark condition. While for the light condition, it is preferred to use 5% sucrose with genotypes Majorca, Rosmarinus officinalis, Pine Scented, and Madeline Hill; and 4% sucrose for genotype APR.

Free access

Phenylalanine ammonia-lyase (PAL) enzyme is the most extensively studied enzyme in the phenylpropanoid pathway. Studies on the biosynthesis of rosmarinic acid (RA) showed that the PAL enzyme catalyzes the initial step of the phenylpropanoid pathway. The increase in RA content in plant tissues in vitro coincided with the increase in PAL activity. The aim of this study was to investigate the activity of the gene responsible for the production of the PAL enzyme in the five rosemary genotypes; this will give more understanding about the accumulation of rosmarinic acid in the five rosemary genotypes. The genotypes were Majorca, Rosmarinus officinalis, Pine Scented, Madeline Hill and APR. Northern blot hybridization between the PAL gene primer and the five genotypes' cDNA showed bands at 300 bp in all the five genotypes for the PAL gene. The expression of the PAL gene was high in genotypes Majorca, Rosmarinus officinalis, and Madeline Hill, while the expression was low in genotypes Pine Scented and APR. It was expected that the genotypes having the highest PAL gene expression will produce the highest amount of RA, but the highest genotype in PAL gene expression Madeline Hill had the lowest RA production in their leaves. This could occur due to the tissue specific regulation inside plant tissues. Inside the callus tissues, where the specific tissue regulation no longer exists, the RA was produced in repetitively large amounts in genotypes with high PAL gene expression.

Free access

The leaf reaction of the Phaseolus vulgaris L. germplasm—UNECA (M6 mutant derived from the cultivar Chimbolito, Costa Rica), `Chimbolito', BAC-6 (Brazil), XAN-159 (Centro Internacional de Agricultura Tropical, Cali, Colombia), and `PC-50' (Domican Republic)—to Xanthomonas campestris pv. phaseoli strain V4S1 (Dominican Republic) were determined in two replicated trials conducted in a greenhouse in Lincoln, Neb. (Feb.–Mar. and July–Aug. 1993). `PC-50' and `Chimbolito' were susceptible to Xcp strain V4S1 in both tests. UNECA, BAC-6, and XAN-159 had similar levels of resistance to Xcp in the July to August trial. However, in the February to March trial, the resistance of UNECA was greater than that of BAC-6 but less than that of XAN-159.

Free access

Abstract

Shoot proliferation of lingonberry (Vaccinium vitis-idaea ssp. minus) was achieved in vitro from shoot tips excised from 1-year-old stock plants and cultured on a low-salt medium supplemented with 2iP. Rooting was obtained without auxin application by placing microshoots in a peat-vermiculite medium in a high humidity chamber. After 6 weeks, the rooted plantlets were transplanted into a peat-lite mix, subjected to a 2-week low humidity acclimation process and subsequently acclimated in a greenhouse under 50% shade. Within 9 months, these plantlets developed a rhizomatous growth habit, in contrast to the nonrhizomatous habit of conventionally rooted cuttings. Chemical names used: N-(3-methyl-2-butenyl)-1H-purin-6-amine (2iP).

Open Access

Shoot tips (7 to 10 mm long) of rosemary plant (Rosmarinus officinalis L. 'Lockwood de forest') were cultured on Murashige and Skoog (MS) medium supplemented with different concentrations of thidiazuron (TDZ) (0, 0.5, 1.0, 1.5, and 2 mg/l) alone or with 3-indole acetic acid (IAA) at 0.5 mg/l. The effect of TDZ and IAA on the proliferation of rosemary shoot tips has been reported in a previous meeting. Here, we report on the effect of TDZ and IAA on the monoterpene constituents identified in the oil of rosemary plants propagated in vitro. The proliferated explants were soaked in hexane as a solvent, then the extractions were used for monoterpene analysis using GC/MS. A significant interaction of TDZ by IAA was found on most of the oil components identified. The highest levels of 1,8-cineole and borneol were obtained at 0.5 mg TDZ/l alone, while the highest level of camphor was obtained at 0.5 mg TDZ/l plus 0.5 mg IAA/l. The highest level of bornyl acetate was at 2 mg TDZ/l.

Free access

The use of buffalograss [Buchloe dactyloides (Nutt.) Engelm] in home lawns and golf courses has been increasing because of its drought resistance and low growth habit. In vitro regeneration of buffalograss at a high frequency may provide an effective tool to introduce new variation for breeding use. The positive effects of AgNO3 on friable embryogenic callus production and regeneration efficiency is well documented in maize. In order to determine if AgNO3 has the same effect on buffalograss, two vegetatively propagated cultivars, a female `609' and a male `45-3' were tested at three different concentrations of AgNO3 at 5, 10, and 15 mg·L–1 using immature inflorescences as explants. Murashige and Skoog medium supplemented with 2 mg 2,4-D/L was employed as the control medium. Medium containing AgNO3 significantly promoted the production of friable callus for `45-3' with the highest percentage achieved at 10 mg AgNO3/L. AgNO3 medium led to production of significantly larger calli than found for the control. However, no difference was detected among 5, 10, and 15 mg AgNO3/L with regard to the callus formation ability and the size of callus initiated on these three treatments. Calli were then transferred to MS medium supplemented with BA at 0.1, 0.5 or 1.0 mg·L–1 to induce shoot formation. BA at 0.5 mg·L–1 gave the best differentiation response. Calli formed in the absence of AgNO3 produced more shoots per callus, but more calli were produced in the presence of AgNO3, and the overall regeneration efficiency was much higher with AgNO3 at 10 mg·L–1. In contrast, AgNO3 showed no promotive effect on callus production and regeneration for `609'.

Free access

Few studies on embryogenesis in common bean (Phaseolus vulgaris L.) have been reported and only the early stages of somatic embryogenesis were observed. Dry seeds from two common bean lines were germinated in darkness on L-6 medium containing 4% sucrose, 0.2 g casein hydrolysate /liter and 2.0 g phytagel /liter. The medium for seed germination was supplemented with 0, 2, 4 or 6μM forchlorfenuron (CPPU). Explants from cotyledonary leaves, petioles, hypocotyls and shoot apices were prepared from 14 day-old seedlings. Callus was derived from explant cultures incubated in darkness at 26C on the medium containing 4 μM 2,4-D and 1 μM Kinetin. The callus was transferred after 4 weeks into 125 ml Erlenmeyer flasks containing 50 ml liquid medium and placed on a gyrotary shaker (120 rpm) under cool-white light (12 μmol.m-2 .s-1 ). The liquid medium was used with 2, 4 or 6 μM of 2,4-D alone or with zeatin supplements at relative concentrations of 0.25 and 0.5. Up to 200 somatic embryos from 40 to 50 mg callus inoculations were induced after 4 to 5 weeks. Callus derived from seedlings grown on CPPU-containing medium gave more repetitive somatic embryos. Cotyledonary stage embryos with clear bipolar structure were observed only from callus derived from seedlings grown on CPPU when transferred to suspension cultures containing 2,4-D and zeatin. All somatic embryos differentiated strong roots and some developed leaf-like structures on conversion medium.

Free access

Callus of Rosmarinus officinalis L. 'Lockwood de forest' was induced from stem segments (3 mm long) using different concentrations of thidiazuron (TDZ). The original stem segments used as explants were found to have a higher level of linalool than was found for leaf segments. Linalool is one of the monoterpenes identified in rosemary plants and it has a pleasant aroma. TDZ has a significant effect on callus formation and callus texture. The callus formed was light green to yellow and/or had some meristimatic dark green cells. TDZ had a significant linear effect on the callus fresh weight. The meristimatic green cells formed on all calli except those proliferated on the lowest concentration of TDZ (0.5 mg/l). No callus was induced from stem segments cultured on TDZ-free medium. The fresh calli from other treatments were soaked in hexane as a solvent for monoterpene analysis using GC/MS. No monoterpenes could be detected in the callus induced on the medium containing the lowest concentration of TDZ. Comparing to the stem segments taken from the parent plants only 4 of 10 monoterpenes identified were found in the callus: α-pinene, β-pinene, 1,8-cineole, and camphor.

Free access