Seed dormancy in Callirhoe involucrata (Torr. & Gray) Gray, (Malvaceae)

2001 Fall.Covers not scanned.Includes bibliographical references.Propagation of Callirhoe involucrata (Torr. & Gray) Gray, for use as a landscape ornamental has been encumbered by a lack of understanding of the seed dormancy and the development of a practical technique for overcoming it. In the populations tested, hard seed accounted for 49 % of an average sample of viable seed. Three disjunct populations of seed, representing two different collection years, were used to investigate practical methods of overcoming impermeability due to hard seed. Methods tested were moist pre-chilling, hot water, leaching, gibberellic acid, hydrogen peroxide, citric acid, potassium nitrate, mechanical and chemical scarification. Standard germination tests were conducted at three-month intervals for 15 months. In addition to hard seed, high percentages of seedless fruit, aborted and unfilled seed were identified. Hand scarification was the most effective means for improving germination in Callirhoe involucrata, resulting in germination as high as 98 %. Scarifying seed with concentrated sulfuric acid was highly effective when a double 60-minute exposure was used, generating germination percentages between 75 - 90 %. Single timed exposure treatments to sulfuric acid stimulated germination in some fractions and caused embryonic damage in others suggesting a variation in seed coat thickness. Similar results were obtained using a pressurized air scarifier; the hard seed coat of some seed fractions were precisely scarified while others were physically damaged using the same treatment. Soaking the fruit in boiling water (100°C) proved to be the most practical means of improving germination (over control) with increases from 12, 22, 30 % to 48, 58 and 91 %, in the three populations respectively. Leaching for 24 and 48 hours in cold (18°C) aerated water showed no improvement over control. A significant increase in germination was established for one lot when leaching occurred for 24 hours in warm (40°C) aerated water. Prechilling at 5°C did not improve germination in unscarified seed. Gibberellic acid, citric acid, and potassium nitrate did not significantly improve germination in scarified seed. Similarly, soaking seeds for 24 hours in 3 % hydrogen peroxide did not increase germination and at a 30 % concentration germination was reduced. Embryo dormancy did not appear to be a factor although some question remains about the presence of chemical inhibitors. The considerable variation in seed dormancy expression may be a function of differences in environmental factors during development. Success was obtained using vegetative stem cuttings dipped in 1.0 % IBA powder and placed under mist. Rooting reached 86 % in some trials

Hydraulic characteristics of pilot distributaries in the Mirpurkhas, Sanghar and Nawabshah districts, Sindh, Pakistan

Discharge frequency / Hydraulics / Flow / Water loss / Seepage / Water distribution / Pakistan / Sindh / Mirpurkhas / Sanghar / Nawabshah

Proceedings of the National Conference on Managing Irrigation for Environmentally Sustainable Agriculture in Pakistan, Islamabad, November 5-7, 1996. Volume I - Inauguration and deliberations

Irrigation managementSustainable agricultureEnvironmental effectsIrrigation canalsFarmer managed irrigation systemsWater distributionIrrigation efficiencyDrainageHydrologyWater reuseTube wellsSoil salinityWater tableWaterloggingGroundwater managementIrrigated farmingInstitution building

Clearigate ® Treatments for Control of Giant Salvinia

Results of recent field trials using the chelated copper formulation Clearigate® 4 showed that applying a 20% solution by volume was effective for controlling populations of giant salvinia in irrigation canals. 5 Lower rates may be efficacious, thereby reducing chemical use and cost; however, little is known about the dose-response effects of Clearigate® against giant salvinia. The objective of this study was to determine the effective rate range of chelated copper applied as Clearigate® for control of giant salvinia

Proceedings of the National Conference on Managing Irrigation for Environmentally Sustainable Agriculture in Pakistan, Islamabad, November 5-7, 1996. Volume V - Papers on the theme, institutional development

Irrigated farmingSocial organizationWater users' associationsFarmers' associationsInstitution buildingWater resource managementOperationsMaintenancePolicyIrrigation managementParticipatory management

Proceedings of the National Conference on Managing Irrigation for Environmentally Sustainable Agriculture in Pakistan, Islamabad, November 5-7, 1996. Volume III - Papers on the theme, Water management below the Mogha

Water allocationWater distributionWatercoursesIrrigation waterIrrigation canalsWaterloggingSalinityWater useDecision makingSurface drainageIrrigation designIrrigation requirementsSprinkler irrigationWheatSurface irrigationIrrigation schedulingCottonCrop yieldSoil reclamationSodic soilsSoil salinityConjunctive useGroundwaterSurface waterFlow measurementIrrigation practicesMonitoringEvaluationFarmer participationFarmers' attitudes

Improved chromatographic detection methods based on absorbance and ultrasonic measurements

Many improvements in science are contingent on understanding complex multi-component systems. Discovering the identity of components within a sample as well as assaying the amount present is the cornerstone of most scientific research. The separatory power provided by chromatography has led to the embrace of chromatographic methods by virtually every discipline within the physical and biological sciences. The widespread usage of chromatography has led to increasing demand for improved instrumental techniques and detection methods. This dissertation describes three new chromatographic detection techniques which provide improved chromatographic selectivity, sensitivity, and detectability. The first chapter presents a basic introduction to chromatography and describes detection methods in gas and liquid chromatography;The project described in the second chapter is a laser-based absorbance probe utilizing fiber optic technology. The probe is applicable to microbore liquid chromatography, providing a sub-microliter cell volume with a 3-mm pathlength. Linear response is made possible by minimizing stray light. This is accomplished first by reducing reflections through refractive index matching, and second, by using a unique optical delay line and high-frequency modulation, which enables background correction through phase-sensitive detection;Chapter 3 describes a new thermal lens spectrometer suitable for microbore LC detection. A single laser is used and a single beam passes through the cell to simplify alignment. Baseline stability of 1 x 10[superscript]-4 and lock-in detection are made possible by a reference beam and high-frequency modulation (150 kHz). Detectability (S/N = 3) is found to be 3 pg of benzopurpurin 4B at 90 mW excitation (514.5 nm). This corresponds to an absorbance LOD of 4 x 10[superscript]-6 au in a 1-cm cell;In Chapter 4 a new detection method for gas chromatography is described. The response of the ultrasonic gas chromatographic detector is used to determine both the absolute weight and the molar concentration of an unknown analyte without a calibration curve. The method does not require that any physical properties of the analyte be known. A detectability of 1 pg of hexane was found. ftn * This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy

Endothall species selectivity evaluation: northern latitude aquatic plant community

Species selectivity of the aquatic herbicide dipotassium salt of endothall (Aquathol® K) was evaluated on plant species typically found in northern latitude aquatic plant communities. Submersed species included Eurasian watermilfoil (Myriophyllum spicatum L.), curlyleaf pondweed (Potamogeton crispus L.), Illinois pondweed (Potamogeton illinoensis Morong.), sago pondweed (Potamogeton pectinatus L.), coontail (Ceratophyllum demersum L.), elodea (Elodea canadensis Michx.) and wildcelery (Vallisneria americana L.). Emergent and floating-leaf plant species evaluated were cattail (Typha latifolia L.), smartweed (Polygonum hydropiperoides Michx.), pickerelweed (Pontederia cordata L.) and spatterdock (Nuphar advena Aiton). The submersed species evaluations were conducted in 7000 L mesocosm tanks, and treatment rates included 0, 0.5 1.0, 2.0, and 4.0 mg/L active ingredient (ai) endothall (dipotassium salt of endothall). The exposure period consisted of a 24-h flow through half-life for 7 d. The cattail and smartweed evaluation was conducted in 860 L mesocosm tanks, and the spatterdock and pickerelweed evaluations were conducted in 1600 L mesocosm tanks. Treatment rates for the emergent and floating-leafed plant evaluations included 0, 0.5, 2.0 and 4.0 mg/L ai endothall, and the exposure period consisted of removing and replacing half the water from each tank, after each 24 h period for a duration of 120 h. Biomass samples were collected at 3 and 8 weeks after treatment (WAT). Endothall effectively controlled Eurasian watermilfoil and curlyleaf pondweed at all of the application rates, and no significant regrowth was observed at 8 WAT. Sago pondweed, wildcelery, and Illinois pondweed biomass were also significantly reduced following the endothall application, but regrowth was observed at 8 WAT. Coontail and elodea showed no effects from endothall application at the 0.5, 1.0, and 2.0 mg/L application rates, but coontail was controlled at 4.0 mg/L rate. Spatterdock, pickerelweed, cattail, and smartweed were not injured at any of the endothall application rates

Cutthroat Flow Measuring Flumes for Flat Gradient Channels

The cutthroat flume can operate either as a free or submerged flow structure. Submerged flow calibration curves and free flow equations have been developed. Rectangular cutthroat flume sizes of 1, 2, 3, 4, and 6 feet were studied and tested in the laboratory. Trapezoidal cutthroat flumes having zero (or V-shaped), 6-inch, and 12-inch throat widths were calibrated. The value of transition submergence is listed for each of the rectangular and trapezoidal cutthroat flumes. The most obvious advantage of a cutthroat flume is economy, since fabrication is facilitated by a flat bottom and removal of the throat section. Another advantage is that every flume size has the same wall lengths in both the entrance and exit sections, allowing the same forms or patterns to be used for any flume size. The use of a consistent geometric shape allows accurate predictions of discharge ratings for intermediate flume sizes. The dimensions and criteria for constructing cutthroat flumes are given. Proper installation and maintenance procedures are described, as well as techniques for measuring flow depths which will yield satisfactory results

Influence of water temperature on the efficacy of diquat and endothall versus curlyleaf pondweed

determine the impact of water temperature on the efficacy of the contact herbicides diquat (6,7-dihydrodipyrido [1,2- α:2’,1’-c] pyrazinediium ion) and endothall (7-oxabicyclo [2.2.1] heptane-2,3-dicarboxylic acid) for control of the exotic nuisance species curlyleaf pondweed (Potamogeton crispus L.) across a range of water temperatures