Fluvial maintenance operations in managed alluvial rivers

• 1 Fluvial maintenance is frequently undertaken to preserve the flood capacity, visual amenity, conservation value and geomorphic stability of managed river channels. Maintenance tasks include the management of both riparian and in-channel vegetation and maintenance dredging.
• 2 Riparian vegetation is traditionally managed by physical methods such as cutting of grasses or removal of trees. Less environmentally severe alternative practices include grazing or shading for grasses, and practices such as pollarding or coppicing for trees.
• 3 While a range of alternative maintenance practices, with varying environmental impact, are usually available for river managers to select, the potential for improving maintenance practices varies according to the particular task considered and the constraints imposed by the need to reach and maintain the target standard of service in terms of flood defence and land drainage.
• 4 This review shows that economic and environmental impacts associated with fluvial maintenance operations may be reduced at three scales. First, at the smallest scale, it is shown that there is often potential for improving the local operational efficiency of individual fluvial maintenance tasks. Second, it may be possible to reduce the intensity of maintenance in channel reaches which are presently over-serviced. Third, at the largest scale, it is shown that efficient maintenance is best achieved within the framework of Integrated Basin Management, and by giving appropriate consideration to future maintenance requirements at the design stage of new projects to reduce the overall need for fluvial maintenance. Examples of the way in which these policies may be implemented to reduce environmental impact without compromising engineering objectives are illustrated through case studies from the UK and the USA.

     

Cell lines and plants obtained after protoplast fusions of Rosa+Rosa,Rosa+Prunus and Rosa+Rubus

Summary Protoplasts of three Rosa cultivars were fused with each other, with protoplasts of Prunus `Colt' and with protoplasts of Rubus laciniatus, using polyethylene glycol 4000 as a fusogen. Protoplasts of Prunus were incapable of cell division and those of Rosa and Rubus were disabled by treatments with metabolic inhibitors, either iodoacetate (IOA) or rhodamine 6-G (R6G). Parental protoplasts were then fused in combinations that required complementation for their survival. RAPD analysis of 41 fusion-derived cell lines showed that two lines resulting from fusions of Rosa + Rosa and one from a fusion of Rosa + Prunus, contained some DNA markers from both fusion partners. The others contained markers of only one fusion parent. This showed that after protoplast fusion, the heterokaryons did not develop into cell lines with stable hybrid nuclei. Plants regenerated from cell lines derived from Rosa + Prunus and Rosa + Rubus fusions contained DNA markers of only Rosa and their DNA amounts were no greater than that of the Rosa parent. However, they differed morphologically from the Rosa parent to a remarkable degree, possibly because they inherited undetected genes of Prunus or Rubus, or because they were somaclonal variants of the Rosa parent. Alternative strategies for the production of somatic hybrids are discussed.     

Tape depth and germination method influence patterns of salt accumulation with subsurface drip irrigation

Subsurface drip irrigation (SDI) can result in accumulation of soluble salts at or near the soil surface. In the southwestern USA, rainfall is usually inadequate for stand establishment, thus supplemental irrigation is necessary. Use of sprinklers to minimize salt concentrations near the soil surface is an alternative to using SDI for stand establishment. Our objective was to evaluate the effects of germination method (irrigation with SDI or sprinklers), depth of SDI tape (0.18 and 0.25 m), and irrigation water salinity (1.5 and 2.6 dS m⁻¹) on salt and Br distribution after each of two consecutive growing seasons. Treatments consisted of factorial combinations of these three factors. Bromide was used to trace salt accumulation from the drip tape. After season 1, the highest salt concentrations (ECe up to 11 dS m⁻¹) were in the top 3 cm of soil. Below 3 cm, soil EC dropped significantly and remained constant to 1.05 m. Similarly, Br concentrations were highest in the top 3 cm of soil. The mass of salt and Br recovered in the top 3 cm were significantly affected by tape depth, and water EC significantly affected salt mass. Salt present in the soil after season 1 adversely affected crop emergence in season 2, where SDI was used for stand establishment. After season 2, the highest salt and Br concentrations were at about 25 cm depth, probably due to 210 mm of rainfall that occurred near the end of the growing season. There were no significant differences among treatments in the mass of either salt or Br in the top 3 cm or 16 cm of the soil profile after season 2. Timely rainfall, transplanting rather than direct seeding, and changing bed geometry can reduce dependence on sprinklers for stand establishment.     

Carotenoid content of 50 watermelon cultivars

The lycopene content of 50 commercial cultivars of seeded and seedless red-fleshed watermelons was determined. Scanning colorimetric and spectrophotometric assays of total lycopene were used to separate watermelon cultivars into low (<50 mg/kg fw), average (50-70 mg/kg fw), high (70-90 mg/kg fw), and very high (>90 mg/kg fw). Cultivars varied greatly in lycopene content, ranging from 33 to 100 mg/kg. Most of the seeded hybrid cultivars had average lycopene contents. Sixteen of the 33 seedless types had lycopene contents in the high and very high ranges. All-trans-lycopene was the predominant carotenoid (84-97%) in all watermelon cultivars measured by high-performance liquid chromatography, but the germplasm differed in the relative amounts of cis-lycopene, beta-carotene, and phytofluene. Red-fleshed watermelon genotypes vary extensively in carotenoid content and offer opportunities for developing watermelons with specifically enhanced carotenoids.     

A stability analysis of time to flowering as a screen for responsiveness to temperature and photoperiod in cowpea (Vigna unguiculata)

Summary Twenty-one genotypes of cowpea (Vigna unguiculata), comprising landraces and varieties, were grown in 22 photothermal environments in Nigeria and Niger, West Africa, and a stability analysis of days from sowing to flowering (f) was carried out. Cowpeas are rarely insensitive to photoperiod; they are typically quantitative shortday plants wherein f is delayed when photoperiod (P) is longer than the critical photoperiod (P _c ). Therefore, in order to quantify genotypic variation in temperature sensitivity, genotype f was regressed against the mean trial f in circumstances where P c (i.e. approximately 13 hd^-1) and mean temperature (T) was between 19° and 28° C. Correspondingly, in order to assess genotypic variation in photoperiod sensitivity, trials where T was near optimal (25°–28° C) but where P ranged from 10–14.5 hd^-1 were used. These stability analyses detected no significant differences (P>0.05) between genotypes 9n temperature sensitivity but revealed significant differences (P<0.001) in photoperiod sensitivity. Regression coefficients from the stability analysis were strongly correlated (r=0.94, 19df) with a photoperiod sensitivity constant, c, determined from a photothermal flowering model. A stability analysis of f from field trials can therefore identify and quantify genotypic variation in response to temperature and photoperiod in cowpea.Abbreviations f days from sowing to flowering - P mean photoperiod - P _c critical photoperiod - P _ce ceiling photoperiod - T mean temperature - T _b base temperature - T _o optimum temperature - SDP short-day plant     

A pilot study on the effect of short-term consumption of a polyphenol rich drink on biomarkers of coronary artery disease defined by urinary proteomics

Polyphenol rich diets have been associated with a reduced risk of cardiovascular disease. We examined the effect of a polyphenol rich (P-R) drink on biomarkers assessed by urinary proteomics. Thirty nine middle aged and overweight subjects were randomized to P-R drink (n = 20) or placebo (n = 19) in addition to their normal diet. After two weeks urine samples were obtained for assessment of the urinary proteome using capillary electrophoresis coupled to a mass spectrometer. A total of 93 polypeptides were found to be candidates for differential distribution with a nominal p-value <0.05, though these differences did not reach significance when multiple testing was accounted for. Sequences were determined in 19 of these demonstrating that they originate from alpha-1 antitrypsin, collagens, fibrinogen alpha and IgG kappa. Levels of 27 polypeptides were greater than 4-fold different between the two groups. Of these, 7 were previously found to be part of a coronary artery disease (CAD) specific urinary biomarker pattern. Their direction of expression was closer to the healthy state in the P-R drink group and closer to CAD state in the placebo group. Our data suggest that the P-R drink may have beneficial effects on urinary biomarkers of CAD. The data encourage the planning of future prospective studies, aimed at investigating significant effects of polyphenol rich dietary products.     

State findings on pesticide residues in food--1988 and 1989

Findings of pesticide and related chemical residues are presented for 27,065 samples of foods collected and analyzed in 10 state food laboratories over 1988 and 1989 (fiscal years (FY) 88 and 89). These laboratories conduct food regulatory programs compatible with national programs of the U.S. Food and Drug Administration. Of the findings, 6325 samples contained detectable levels of 1 or more pesticide analytes and 418 (or 1.5%) of the total number of samples were deemed to be of regulatory significance.