Thermal regime of tundra soils under reclamation and restoration of natural vegetation

This paper covers the specifics of the temperature regime in reclaimed tundra soils under a sown perennial herb meadow and a restored (secondary) ecosystem as compared to the small-shrub yernik (birch)-willow-moss and shrub yernik-willow-moss tundra types. The taxonomic position of the anthropogenic soils and those of the secondary (restored) biogeocenosis is discussed as related to the transformation or regeneration of the biotic and thermal components of the biogeocenosis. The soil development causes profound changes in the freezing-thawing regime, which gives grounds to distinguish the developed soils as an individual soil type.     

Chemical composition of atmospheric precipitation and lysimetric water in an iron-illuvial podzol under mixed forest plantations in the Republic of Komi

Data on the migration of soluble organic compounds and other elements in the profile of an iron-illuvial podzol under mixed forest plantations are analyzed. It is demonstrated that the contents of organic compounds and chemical elements in lysimetric water are subjected to considerable seasonal dynamics. The transformation of the chemical composition of the lysimetric water in the soil profile is discussed.     

Lipid fractions with aggregatory and antiaggregatory activity toward platelets in fresh and fried cod (Gadus morhua): correlation with platelet-activating factor and atherogenesis

Cod (Gadus morhua) is a popular part of the diet in many countries on both sides of the North Atlantic; in most cases it is consumed fried. In this study, total lipids of cod muscle were separated into neutral and polar lipids, which were further fractionated by HPLC. The lipid fractions were tested in vitro, against washed rabbit platelets, for the probable existence of lipid compounds that either exhibit an action similar to that of platelet-activating factor (PAF) or inhibit the action of PAF. The platelet bioassay was used to evaluate total lipids, total polar lipids, and total neutral lipids, before any further separation. Detection of these compounds in fresh and fried cod could be used to evaluate the nutritional value of this important fish. The in vitro biological study of lipids showed that in fresh cod lipid fractions, ranges of PAF-like and anti-PAF-like activities were present, whereas in fried cod lipid fractions, both neutral and polar, anti-PAF activities were mainly observed. Because it has already been reported that PAF is involved in atheromatosis generation, the existence of PAF inhibitors in cod may contribute to the possible protective role of fish, in this case cod, against atherosclerosis.     

Characterization of core collection of lentil germplasm for phenology, morphology, seed and straw yields

Increasing and maintaining crop residues in predominantly cereal-based rotations of the US Pacific Northwest is critical to controlling soil erosion. The core collection of lentil (Lens culinaris Medik.) germplasm comprising 287 accessions was evaluated for variation in phenological, morphological and growth parameters including seed yields and residue amounts over a two-year period under conventional tillage and no-till conditions. The objectives of this study were (i) assess lentil genetic variation in germplasm for variation in biomass production and seed yield, (ii) assess the relationship of phenological and morphological traits with biomass and seed yield and (iii) identify high biomass producing germplasm for use as parents in the breeding program. Days to flowering and days to maturity ranged from 31 to 78 and from 71 to 106 days, respectively. Time to flowering in terms of cumulative heat units was a more efficient measurement than days to flowering. Plant height and plant canopy width had a significant association with total biomass, seed yield and residue amounts. Total biomass ranged from 788–6389 kg ha^–1 under conventional tillage, while the range under no-till conditions was 1045–6195 kg ha^–1. Most of the lines with higher biomass also produced the highest seed yields and residue amounts. Overall, only one accession produced more residue than `Laird'. In the more favorable environment of 1997, six accessions exceeded the control cultivars, `Laird' and `Indianhead', for residue amounts, and seven and twenty-four accessions exceeded control cultivars, `Pardina' and `Brewer', for seed yield. Results indicated that plant height, canopy width at maturity and seed yield explained most of the variation in biomass and residue production. Large seeded germplasm consistently had a longer reproductive growth period than small seeded accessions and had 17%, 7% and 21% more biomass, seed yield and residue, respectively. Our data indicated significant variation in lentil germplasm for biomass, seed yield and residue amounts to warrant their use in the breeding program.     

Single-flowered vetch (Vicia articulata Hornem.): A relic crop in Italy

Single-flowered vetch (Vicia articulata Hornem.), a crop native of the Mediterranean area, is widespread mainly in south Europe, in west Asia and Australia for forage, green manure and human food. In Italy this crop was still cultivated in the 1950s but, later, no records concerning its cultivation were available. This strongly suggested to place V. articulata among the Italian crop species that disappeared in the 20th century. In the course of a collecting expedition in Sardinia, a relic population, mistaken for lentil, was found. This population has been characterised from a botanical, nutritional and cytological point of view. V. articulata appears to be lower in nutritional quality than lentil. However, within the framework of a sustainable agriculture, V. articulata could find interesting opportunities. In fact, its role in soil conservation and rescue of marginal areas could be interesting, as well as its potentialities as a source of useful genes in breeding programmes.     

Photodegradation of metolachlor: isolation, identification, and quantification of monochloroacetic acid

The photolysis of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] in a sunlight simulator under actinic radiation was investigated. The focus of the study was to determine the extent of monochloroacetic acid (MCA) production. MCA was concentrated and derivatized from photolysate as the n-propyl ester using propanol and sulfuric acid and then identified as the ester using GC/MS and GC/ECD. On the basis of regression analysis, it was shown that the direct photodegradation of approximately 10 microM metolachlor followed pseudo-first-order kinetics with respect to the metolachlor concentration, and the half-life of the herbicide ( approximately 74 h) was independent of the pH of the medium. Photolysis in synthetic field water (SFW) resulted in a significant reduction of photolysis time (t(1/2) approximately 9 h). Direct photolysis experiments indicate a 5.19 +/- 0.81% (n=3) conversion of metolachlor to MCA, while photolysis in synthetic field water and in a Don River water sample resulted in 29.8 +/- 4.6% (n = 3) and 12.6 +/- 4.1% (n = 3) conversion, respectively; MCA was shown to be hydrolytically stable over the time course of the photoreaction. The photodegradation of alachlor, butachlor and a model chloroacetanilide, 2-chloro-N-methylacetanilide, in SFW were also investigated.     

Partial resistance to Erysiphe graminis hordei in old European barley varieties

Summary A collection of 133 genotypes consisting mainly of old European barleys and land varieties was assessed for level of partial resistance to barley mildew at the adult plant stage. Identification of any known resistance factors conferring hypersensitive reactions to the mildew races present at various frequencies in N.W. Europe was ensured through seedling tests with an appropriate AO mildew isolate.Thirty-nine varieties with relatively high levels of adult (partial) resistance and lacking known race-specific resistance genes were tested over a period of three years in field disease nurseries. At least thirteen varieties showed significantly less percentage leaf area infected than the control variety Proctor. These constitute a useful reserve of non-hypersensitive resistance, probably under the control of genes with mainly additive effects. In combination, these genes give enhanced levels of resistance, which could be of a more stable nature.     

Intra-varietal variation for in vitro plant regeneration in the genus Trifolium

Summary Seedlings of Trifolium repens showed considerable variation with regard to the morphology and growth of their calli, and their ability for in vitro differentiation of shoots. One of the lines selected for regeneration in primary callus cultures also showed shoot formation from protoplasts. Somatic embryogenesis in callus cultures of T. pratense and T. arvense occurred only in selected seedling lines. This paper highlights the importance of screening a large number of plants within a cultivar of outbreeding species to achieve reproducible plant regeneration from tissue culture.     

Rapid HPLC screening of jasmonate-induced increases in tobacco alkaloids, phenolics, and diterpene glycosides in Nicotiana attenuata

A rapid, HPLC-based screening procedure for the main classes of secondary metabolites in Nicotiana attenuata leaves (alkaloids, phenolics, and diterpene glycosides) is reported. In a single step, leaves are extracted in aqueous acidified (0.5% acetic acid) methanol, and the extracted compounds are separated by reversed-phase HPLC with an acidic water/acetonitrile gradient in <30 min. The utility of the method in quantifying changes in the secondary metabolites after methyl jasmonate treatment of the plants, a treatment known to elicit resistance to herbivores in nature, is illustrated. Methyl jasmonate treatment elicited dramatic increases in some secondary metabolites (caffeoylputrescine, nicotine, and diterpene glycosides increased 12.5-, 1.4-, and 1.9-fold, respectively) but left others, such as rutin, unchanged. Such broad-based analytical screens will help characterize environmental and genetic changes in secondary metabolite profiles.