Systematic designs for experiments with mixtures

In this paper systematic designs for experiments with mixtures are developed. The plan of analysis of the experiment is discussed for a quadratic model of SCHEFF É (1958) for q-component mixture with orthogonal polynomials of third degree describing the time trends.     

Artificial injury experiments on the damaging effect of Leucoptera malifoliella on apple trees

In 1986 and 1987 defoliation experiments on the apple cultivar Herma were performed to simulate the occurrence of Leucoptera malifoliella Costa. Those model experiments were based on investigations on the mine size of Leucoptera malifoliella and yield loss on infested and tagged trees. Defoliation carried out by hand showed that heavy leaf loss reduced fruit number. Insufficient nutrient supply due to reduced leaf area and a consequently smaller leaf-fruit ratio led to a decrease in mean fruit size and total yield. Heavy leaf loss had also an adverse effect on fruit quality components (dry matter substance, viscosity, total sugar and acid content of fruit juice). This was finally reflected in sensory evaluation criteria. Heavy leaf losses also influenced blossom bud differentiation in the blossom set of the following year. Both number of inflorescences and number of blossoms per inflorescence were reduced. The evaluation of the extent of damage of L. malifoliella was based on previous investigations on reduced leaf area. For L. malifoliella a mean mine size of 0.96 cm² was found. This corresponds to a 4.2% loss of leaf area.The leaf-fruit ratio is of special importance for the evaluation of the extent of damage of leaf-damaging pests and was used to derive injury threshold ranges for L. malifoliella. Previous investigations on L. malifoliella infestations and the results from the artificial defoliation experiments enabled the determination of preliminary flexible injury thresholds. Depending on leaf-fruit ratio, yield level, and leaf miner generation, the thresholds vary between 0.1–2.5 eggs and mines per leaf.     

Model Trials for Phytoremediation of Hydrocarbon-Contaminated Sites by the Use of Different Plant Species

In order to further the development of plant-based remediation of sites contaminated by carbo-chemical and petro-chemical industries, the penetration of the roots of Phragmites australis in contaminated soil substrate was studied in model trials. The series of experiments contained model substrate with firm bitumen and tar. In terms of the level of root penetration, the roots and rhizomes penetrated equally through the middle of the pot and at the edges as well as coming up through the bottom. There were differences between the density of the root systems in the topsoil of the two variations, with the roots in the sample with a 3.5 -cm bitumen layer being more dense. The experiment also showed that shallow rooting plants can penetrate thick barriers and are suitable for planting in contaminated areas. In the subsoil zone, which contained many roots, a reduction of up to 85% in the MOH content was observed. In a second series of long-term pot experiments, the stimulation of hydrocarbon remediation by Phragmites australis, Alnus glutinosa, and Robinia pseudoacacia was studied. In the subsoil zone, which contained many roots, a reduction of up to 64% in the hydrocarbon content was determined. In the comparison between the cropped and noncropped treatments, the decontamination ratio was up to 40% higher in the cropped pots than in the pots without plants. For a determination of microbial activity, two enzymes (catalase, ß-glucosidase) and microbial biomass were measured. Variants with plants showed higher microbial activities than uncropped pots. By increasing “biostimulation,” pollution and also the leaching of pollutants can be reduced.     

Food remains from Bronze Age-Archondiko and Mesimeriani Toumba in northern Greece?

Finds of fragmented cereal grain from the sites of Mesimeriani Toumba and Archondiko in Macedonia, northern Greece, dated to 2100-1900 cal. B.C. provide the basis for the experimental investigation of the effects of a) fragmentation before and after charring, b) treatment of grain with water and c) charring conditions, on the morphology of the fracture surface. The experiments indicate that it is possible to distinguish fragmentation before and after charring and, with low charring temperatures, it is possible to distinguish prior treatment of grain with hot water. Comparison of the archaeological grain with the grain produced experimentally suggests that both archaeologieal finds represent ground grain, and at least those from Mesimeriani correspond to some type of wheat bulgur, probably intended for human consumption. These finds mark the prehistoric origins of a foodstuff widely used in Mediterranean cuisine. Further experimentation along the lines followed here would be desirable. Received January 8, 2002 / Accepted April 1, 2002     

Studies on Sporopollenin Biosynthesis in Tulipa Anthers

Investigations were carried out to clarify sporopollenin biosynthesis. Tracer experiments were focussed on the incorporation of specifically labeled ¹⁴C-phenylalanine into sporopollenin. In addition, the incorporation of further ¹⁴C-labeled substances, such as glucose, acetate, malonic acid, mevalonate and tyrosine, was investigated. The sporopollenin fraction was isolated and purified by a gentle method including extractions by different solvents, incubations with hydrolyzing enzymes and fractionated saponifications. During the purification procedure the whereabouts of the initially applied radioactivity was followed. After each step the remaining as well as the released radioactivity was determined. Saponification of samples labeled after application of phenylalanine yielded p-coumaric acid and p-coumaric acid methyl ester as labeled products. In comparison with the other substances applied, the highest incorporation rates were obtained with phenylalanine, regardless of the position of labeling. After degradation of the sporopollenin sample labeled with ring-¹⁴C-phenylalanine, p-hydroxybenzoic acid was detected as the main labeled product. These results unequivocally show that an integral incorporation of the aromatic ring system occurred. Tracer experiments were carried out at different stages of development. Their results show that, although the incorporation rates of ¹⁴C-phenylalanine into sporopollenin differ, the substantial incorporation of this substance is not bound to defined stages of development.     

A simple device for sorting live benthic invertebrates into size groups

A sorting device for automatic sorting of benthic invertebrates into size groups is described. The animals are placed in the top of the apparatus and move downwards until they are unable to move further down. The advantages are less possibility of injuring animals and large yield of experimental animals with little effort. This revised version was published online in July 2006 with corrections to the Cover Date.     

Factors delimiting the boundary between vertically contiguous mussel beds ofSeptifer virgatus (Wiegmann) andHormomya mutabilis (Gould)

On moderately wave-exposed rocky shores in middle Japan, the upper interidal mytilid,Septifer virgatus, and lower intertidal mytilid,Hormomya mutabilis, occur together, forming vertically contiguous mussed beds. Factors limiting the lower distribution limit ofSeptifer and the upper limit ofHormomya were investigated by collections of natural mussel clumps and single- and mixed-species transplantation experiments. Newly settled juvenileSeptifer (<5 mm shell length) were significantly fewer in the natural and artificialHormomya clumps than in theSeptifer clumps. Both natural and artificialHormomya clumps accumulated a much greater amount of sediment than did theSeptifer clumps.Hormomya clumps inhibited the recruitment ofSeptifer, presumably through accumulation of sediment, which resulted in setting the lower limit of theSeptifer zone. Survivorship of small (5–10 mm) and large (>15 mm)Hormomya was much lower inHormomya clumps transplanted upwards into theSeptifer zone than it was inHormomya clumps in theHormomya zone. In mixed-species clumps in theSeptifer zone, however, survivorship of smallHormomya was not significantly different from that in mixed-species clumps in theHormomya zone.Septifer had a positive effect on the survival of smallHormomya and increased the upper limit ofHormomya, presumably by providing shelter and thus protecting them from desiccation. The upper limit ofHormomya zone was thus considered to be set by desiccation exceeding the physiological tolerance of the species.