961 research outputs found

    Numerical Taxonomy of Anaerobic Bacteria Isolated from Ground Water of a Sanitary Landfill

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    Section I: Facultative and obligatory anaerobic bacteria were isolated from the ground water of a sanitary landfill characterized by sandy soil and a periodically high water table. Isolates were examined for 63 characteristics and subject to numerical analysis. Eight clusters were established and correlations with conventional taxonomy were made. The Bacteriodaceae were found to be the dominant group of organisms by the methods employed. The anaerobic population was observed to decrease as the period of seasonal rainfall ended. At the same time, gram positive anaerobes were largely replaced with gram negative ones. Leaching between sampling sites (wells) made correlations between metabolic end products (observed by gas-liquid chromatography) and metabolites produced by the organisms in vitro, impossible. Attempts were made to modify the original test battery to create a smaller battery which would yield approximately the same groupings as the original battery. Clusters became less discreet with these modifications and probably unacceptable for detailed taxonomic work. Section II: An index is described which measure the goodness of fit of an organism within a phenon as established by numerical taxonomy. A hypothetical mean organism was established for each phenon. Similarity and relevance coefficients were generated between this hypothetical organism and each member of the phenon. The product of these two coefficients has been termed the Index of Relevance and Similarity (IRS). This index ranges from zero to unity and can be generated with two-state and/or multistate data

    Initiation of Terpenoid Synthesis in Osmophores of \u3ci\u3eStanhopea anfracta\u3c/i\u3e (Orchidaceae): A Cytochemical Study

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    The terpenoid component of the osmophore fragrance in Stanhopea species is composed of isoprene units synthesized via the mevalonic acid pathway. Localization of hydroxymethylglutaryl CoA synthase in the pathway was achieved using a technique which elicits the formation of an electron- dense precipitate of uranyl ferrocyanide at the point where an acetyl group from acetyl CoA is transferred to acetoacetyl CoA, releasing free CoA-SH. Applying this technique to cells of the osmophore of S. anfracta resulted in a precipitate between the inner and outer mitochondrial membranes, in the smooth endoplasmic reticulum, and, to a lesser extent, on the outer surface of the tonoplast membranes and between the inner and outer membranes and granal membranes of amyloplasts. These findings indicate multiple subcellular locations for at least some enzymes in the mevalonic acid pathway. Localization of carnitine acetyltransferase by a similar technique resulted in a precipitate between the inner and outer mitochondrial membranes and in the smooth endoplasmic reticulum, indicating multiple localization for this enzyme

    Osmophores of \u3ci\u3eStanhopea\u3c/i\u3e (Orchidaeceae)

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    Species of the Neotropical orchid genus Stanhopea produce a fragrance comprising terpenoids and aromatics which attracts euglossine bee pollinators. The secretory tissue, called an osmo- phore, is located in the adaxial region of a sac formed near the proximal portion of the floral lip. This region is easily recognized in Stanhopea oculata and S. wardii because it is papillate. The osmophore in these two species includes all the cells of the papillae and those directly below, that grade into fundamental tissue. Osmophore cells are more densely cytoplasmic than cells in the adjacent tissue. Numerous amyloplasts and mitochondria are seen in these cells from the earliest bud stages we examined through anthesis. Smooth and rough endoplasmic reticulum are abundant, but dictyosomes are uncommon. Mitochondria of osmophore cells appear to be distributed with no apparent pattern during bud stages, although they tend to be aligned near the plasmalemma at anthesis. Osmophore cells are highly vacuolate after anthesis

    Strawberry Anthracnose: Histopathology of \u3ci\u3eColletotrichum Acutatum\u3c/i\u3e and \u3ci\u3eC. fragariae\u3c/i\u3e

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    Ontogeny of the invasion process by Colletotrichum acutatum and C. fragariae was studied on petioles and stolons of the strawberry cultivar Chandler using light and electron microscopy. The invasion of host tissue by each fungal species was similar; however, each invasion event occurred more rapidly with C. fragariae than with C. acutatum. Following cuticular penetration via an appressorium, subsequent steps of invasion involved hyphal growth within the cuticle and within the cell walls of epidermal, subepidermal, and subtending cells. Both species of fungi began invasion with a brief biotrophic phase before entering an extended necrotrophic phase. Acervuli formed once the cortical tissue had been moderately disrupted and began with the development of a stroma just beneath the outer periclinal epidermal walls. Acervuli erupted through the cuticle and released conidia. Invasion of the vascular tissue typically occurred after acervulus maturation and remained minimal. Chitin distribution in walls of C. fragariae was visualized with gold-labeled wheat germ agglutinin. The outer layer of bilayered walls of conidia, germ tubes, and appressoria contained less chitin than unilayered hyphae in planta

    Water Uptake Threshold of Rabbiteye (\u3ci\u3eVaccinium ashei\u3c/i\u3e) Blueberries and Its Influence on Fruit Splitting

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    Split-resistant and split-susceptible rabbiteye blueberry fruit were evaluated at all stages of development to determine \u27\u27water uptake thresholds\u27\u27 by soaking in distilled water. Weight increase after soaking was measured, and percent weight gain was calculated to take into consideration the weight increase of the fruit from development. The ratio of percent increase in volume to weight increase resulting from water uptake was calculated. Ratios of percent water uptake to weight increase between splitsusceptible \u27Tifblue\u27 and split-resistant \u27Premier\u27 blueberries were found to be similar. The split-susceptible \u27Tifblue\u27 had a 1.6 g/50 fruit increase with a 1.7% water uptake and a ratio of 1.08. \u27Premier\u27 had a higher weight increase with 3.3 g/50 fruit and also a higher percentage of water uptake at 3.6% providing a ratio of 1.09. Although both absorbed water at a constant rate shown by a linear increase of weight increase over time, \u27Premier\u27 absorbed a significantly greater amount of water than did \u27Tifblue\u27 yet remained intact and did not split

    Survey of Blueberry (\u3ci\u3eVaccinium\u3c/i\u3e spp.) Problems in the Gulf South

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    The blueberry (Vaccinium) industry in Mississippi has been steadily increasing since the early 1980s, but some plants in older fields are now in decline. The root rot pathogen, Phytophthora cinnamomi, is endemic in the southeastern United States and has caused severe losses to blueberries in North Carolina and Arkansas. Because the warm, humid climate of Mississippi, with periods of high precipitation, provides a favorable environment for Phytophthora root rot disease, it was suspected to be the cause of plant decline in older blueberry fields. Members of the Gulf South Blueberry Growers Association were mailed surveys to determine cultural practices and the extent of losses in their blueberry fields. The survey was written in partial, open-ended question format with 33 questions pertaining to cultivars, number of hectares planted, cultural practices, overall health of the blueberry plants, and losses due to diseases, insects, or other problems. Fifty-eight of 146 surveys (40%) were completed and returned. 89% of respondents grew rabbiteye (Vaccinium ashei) cultivars and the balance grew southern highbush (V. corymbosum hybrids) cultivars. The average number of plants per hectare was 1523 with the majority of plants 10 - 20 years old. 79% of the growers described the overall condition of their plants as average, healthy, or vigorous. The most common cause of plant death cited was environmental with damage caused by the 2004 and 2005 hurricanes at the top of the list. No major diseases were reported by 36% of the respondents, while mummy berry (Monilinia vaccinii-corymbosi [Reade] Honey), leaf spots (many causal organisms), and root rot (Phytophthora cinnamomi Rands) were noted as problems by 22, 15, and 10% of the growers, respectively. Phytophthora species were isolated from root and soil samples collected from symptomatic plants on three farms. Weeds were listed as problems on 100% of the surveys. 47% of the respondents plan to increase their blueberry plantings mainly with rabbiteye cultivars

    Laboratory Method to Estimate Rain-Induced Splitting in Cultivated Blueberries

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    Preharvest rainfall that occurs when fruit are fully ripe or approaching full ripeness can result in detrimental fruit splitting in rabbiteye and southern highbush blueberries. This study was initiated to develop a laboratory method to model rain-related incidence of splitting in cultivated blueberries with the goal of predicting the incidence of splitting in blueberry cultivars and selections. Multiyear field surveys of rabbiteye and southern highbush cultivars show that the incidence of rain-related splitting is strongly cultivar-dependent. Laboratory values for forced splitting and naturally occurring rain-related field splitting data show a strong correlation indicating that the incidence of fruit splitting can be accurately estimated by this laboratory method. Soaking the berries in distilled water 14 h at room temperature gives a confident determination of splitting tendencies. Blueberry breeders and geneticists can use this method to evaluate new potential blueberry cultivars for splitting tendencies as part of routine screening. This would lead to a long-term goal of reducing splitting susceptible blueberry cultivars in commercial plantings

    Stem Cutting Propagation in Whole Pine Tree Substrates

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    Wood-based substrates have been extensively evaluated for greenhouse and nursery crop production, yet these substrates have not been evaluated for propagation. The objective of this study was to evaluate processed whole loblolly pine trees (WPT) (Pinus taeda) as a rooting substrate for stem cutting propagation of a range of ornamental crops. Substrates included processed WPT, pine (Pinus sp.) bark (PB), and each mixed with equal parts (by volume) peatmoss (PM) (WPT:PM and PB:PM, respectively). Substrate physical (air space, container capacity, total porosity, bulk density, and particle size distribution) and chemical [pH and electrical conductivity (EC)] properties were determined for all substrates. Rooting percentage, total root length, total root volume, and total shoot length were evaluated for four species in 2008 and five species in 2009. Substrate air space was similar between PB and WPT in the 2008 experiment, and likewise between PB:PM and WPT:PM. In the 2009 experiment, PB and WPT had similar substrate air space. The addition of PM to PB and WPT resulted in reduced air space and increased container capacity in both experiments. The proportion of fine particles doubled for PB:PM and WPT:PM compared with PB and WPT, respectively. Substrate pH for all substrates ranged from 6.0 to 6.9 at 7 days after sticking (DAS) cuttings and 6.9 to 7.1 at 79 DAS. Substrate EC was below the acceptable range for all substrates except at 7 DAS. Rooting percentage was similar among substrates within each species in both experiments. The addition of PM resulted in significantly greater total root length for PB:PM and WPT:PM compared with PB and WPT, respectively, for five of the eight species. Shoot growth was most vigorous for PB:PM compared with the other substrates for all species. The study demonstrated a range of plant species can be propagated from stem cuttings in whole pine tree substrates alone or combined with PM

    Osmophores, Floral Features, and Systematics of \u3ci\u3eStanhopea\u3c/i\u3e (Orchidaceae)

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    The floral fragrance glands (osmophores) of 18 species of Stanhopea and Sievekingia were examined through a series of developmental studies at light and electron microscope levels including late bud stages through postanthesis. Various characters were identified to be of potential systematic value and were recorded for each species. These characters included: texture of the osmophore surface, number of distinct cell layers comprising the osmophore, nature of lipid inclusions in osmophore cells, and presence or absence of plastoglobuli in osmophore amyloplasts. These characters were combined with traditional features of floral lip morphology for cladistic analysis. Sievekingia was the postulated outgroup. Stanhopea ecornuta showed the largest number of plesiomorphic characters. Stanhopea pulla, S. annulata, and S. candida were only slightly more derived. Stanhopea anfracta, S. gibbosa, S. martiana, S. oculata, S. radiosa, S. ruckeri, S. saccata, S. shuttleworthii, S. tigrina, S. vasquezii, and S. wardii form a monophyletic group that can be recognized by a labellum with an articulated epichile and a bicornuate mesochile (or hypochile). Stanhopea tricornis may be a hybrid between a species of Sievekingia and Stanhopea

    Evaluation of CAY-1, an Experimental, Natural Fungicide, For Control of Strawberry Pathogens

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    CAY-1 is an experimental, natural product being tested as a potential fungicide. This saponin isolated from Capsicum frutescens interacts with membrane sterols causing leakage of cell components and ultimately cell death in a variety of fungi. CAY-1 and the commercial fungicide captan were tested in an in vitro doseresponse dilution-broth assay. They caused at least 85% growth inhibition of the fungal pathogens Colletotrichum acutatum, C fragariae and C. gloeosporioides when tested at 3.0 μM. Even though CAY-1 strongly reduced the growth of these fungal pathogens in laboratory assays and prevented anthracnose development in detached leaf assays, it did not control foliar or fruit rot diseases of strawberry in field trials
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