Gewinnung und Verwendung geringwertigen Holzes

Ohne Zusammenfassung     

Use of force-deformation curves to estimate Young's modulus and its applications to soil aggregate breakdown

Soil aggregates from a clay and a sandy loam were subjected to uniaxial compression and their force-deformation relationships determined. From these relationships the elastic deformation was identified, and estimates were made of Young's modulus, elastic strain energy and work of fracture. Also estimated were the increases in surface area produced on breakdown and hence surface energies. The results were interpreted in terms of Griffith's crack theory, and apparent crack lengths were calculated. The calculated values were high, but the variability of the data prevented a full assessment of this approach to the study of brittle failure of aggregates.     

Field release of a non-toxigenic Aspergillus flavus L strain in central Benin

Journal of Plant Diseases and Protection - Non-toxigenic strains of Aspergillus flavus (Link) can be used as biological control agents to reduce the contamination of grains such as maize with...     

Influence of Phytohemagglutinin on the Agronomic Performance of Beans (Phaseolus vulgaris L.)

The abundant lectin phytohemagglutinin (10 % of total seed protein) does not contain sulfur amino acids and, being a potent antimetabolite, it is responsible for the lowering of the nutritional value of bean seeds. The aim of the present work was to improve the dry bean cultivar ‘Taylor's Horticultural’ (Asgrow), by genetically introducing the lectin null (lec/lec) character from two null genotypes: ‘Pinto UI 111’ and ‘Heidi’. Thirty-seven BC²F₃ and fourteen BC₆F₅ inbred lines were evaluated in agronomical trials. Analysis of Variance (ANOVA) showed significant differences among BC₂F₃ breedings lines for all traits under evaluation. Comparison of the LedLee genotypes versus lec/lec did not show statistically significant differences in the means for the following traits: yield, yield components and percentage of protein in the seed. Fourteen BC6F5 lines, compared together with their recurrent parent ‘Taylor's Horticultural’, showed significant differences among genotypes for 1000 seed weight, protein percentage on dry matter and ash percentage. No significant differences were observed for grain yield. The data indicate that lectin removal did not have a detrimental effect on the traits evaluated.     

Biological activity in the profiles of chernozems as dependent on the character of their agricultural use and microtopography

The biological activity of soil samples taken from genetic horizons of plowed and virgin chernozems in the Kamennaya Steppe Reserve was determined as the amount evolved from the soil upon its incubation in laboratory conditions. In the top humus horizons, the biological activity of virgin chernozem was two to three times higher as compared with that in the plowed chernozem. The intensity of biological processes and the microbial biomass in the soil profile was mainly controlled by the quantity and quality of soil organic matter. Long-term agricultural use exerted a weaker effect on the biological properties of chernozems developed on microelevations (blocks) of the paleocryogenic microtopography in comparison with chernozems developed in the microdepressions between the blocks. The factor analysis showed that soil characteristics related to the biological processes comprise more than 50% of the total variance of factor loads and are distinctly differentiated in the soil profile.     

The incidence of Pythium spp. and Aphanomyces cochlioides associated with the sugar-beet growing soils of Britain

In a survey of fungi causing seedling diseases of sugar beet using a soil bioassay, Aphanomyces cochlioides and Pythium spp. were found to occur in 39% and 31%, respectively, of 341 sugar-beet fields selected in a stratified random sample in England, The frequency of A. cochlioides-infested soils varied widely in the different sugar-beet growing areas of the country. Soil pH was the single factor most strongly associated with the distribution of the pathogen, but regression models applied to combinations of factors indicated that soil texture and the interval between sugar-beet crops were also relevant to its frequency. It was detected less often in soils of high pH (≥ 75). heavy texture and where the interval between sugar-beet crops exceeded 5 years. No significant associations were found between the proportion of soils with Pythium spp. and soil or cropping factors.