Showing papers by "Swedish University of Agricultural Sciences published in 1984"

Distribution of birch (Betula SPP.), willow (Salix SPP.), and poplar (Populus SPP.) secondary metabolites and their potential role as chemical defense against herbivores.

Abstract: Isoprenoids and phenolics, major metabolites of important browse species, are reviewed in regard to concentrations, distribution within tissues, and between species. Seasonal variation of specific substances and changes with age of the plant are also considered. The distribution of substances may affect food selection and feeding behavior of animals. Wild mammalian herbivores tend to avoid plant parts rich in these substances, in spite of high nutritional content of the plant tissue. Possible mechanisms for defense by plants against depredation by mammalian herbivores are discussed within the framework of the plants' biochemistry.

High growth rate and regeneration capacity of hypocotyl protoplasts in some Brassicaceae

Abstract: Protoplasts isolated from 4-day-old hypocotyls of various species of Brassica (Brassica napus, B. campestris and B. oleracea) produced callus with high efficiency in media containing casein hydrolysate and high concentrations of the auxin 2,4-D (4.5 μM). Cell division began after 24 h and 60% of the cells had divided after 48 h. In contrast, protoplasts isolated from stem and mesophyll of plants grown in vitro or in the greenhouse began to divide after a delay of 3–5 days. In these cases 40–50% of the cells had divided after 5 days as compared to 70% for hypocotyl protoplasts. To obtain a high frequency of regeneration, rapidly growing calli were transferred to media having a high cytokinin:auxin ratio as early as possible, usually 3 weeks after protoplast isolation. The average regeneration frequency for calli obtained from mesophyll protoplasts was 50%, while as many as 70% of the calli derived from hypocotyl protoplasts of B. napus regenerated plantlets on a medium containing zeatin (9.1 μM) and IAA (0.6 μM). On the same medium regeneration of Brassica oleracea was obtained. A low percentage of calli (1%) from Brassica campestris formed shoots when cultured on a combination of zeatin (4.6 μM), BA (4.4 μM) and IAA (0.6 μM).

Decomposition of root litter and some factors regulating the process: long-term root litter decomposition in a scots pine forest

Abstract: Decomposition of root litter was studied using Scots pine roots (six diameter classes) and rhizomes from heather (three diameter classes) and cowberry (one diameter class). For Scots pine roots, root diameter was correlated with initial concentrations of N, P, S and Mg but not with organic-chemical composition. The highest nutrient concentrations were found in Scots pine roots and the lowest in heather rhizomes, with cowberry rhizomes intermediate. The highest lignin concentrations were in heather and cowberry rhizomes. In the early decomposition stages diameter and nutrient concentration correlated with mass loss rate in Scots pine roots: in a comparison Scots pine roots were degraded faster than cowberry rhizomes which, in turn, were degraded faster than heather rhizomes. Root diameter, however, may not be important in decomposition of cowberry and heather rhizomes but nutrient and lignin concentrations appear important in all three species. In the late decomposition stages only Scots pine roots could be compared and it appeared that there was a negative correlation with lignin concentration and mass loss, and no correlation with any nutrient.

Lack of correspondence between genetic and morphologic variability patterns in Atlantic herring (Clupea harengus)

Abstract: The Atlantic herring (Clupea harengus) stock complex is confusing from the perspectives of both evolutionary biology and systematics. There are numerous ecologically and morphologically divergent stocks classified as species, subspecies, races, tribes, etc. with an unknown degree of genetic differentiation and reproductive isolation between them. The genetic population structure of herring from the Scandinavian waters was analysed electrophoretically. The pattern for distribution of genetic variation was compared to that of the morphological characters most frequently used for stock classification, i.e., the number of vertebrae and keeled scales. Fish were collected from 17 locations distributed from the northern Gulf of Bothnia to the north-east Atlantic off the west coast of Norway. The genetic analysis was based on 17 electrophoretic loci, 13 of which were variable. There are statistically significant allele frequency heterogeneities, but there is a conspicuously small amount of genetic differentiation, even between stocks classified as representing different subspecies. More than 99 per cent of the total gene diversity was found within populations, and genetic distances are typically of the order of 0·001. The genotypic distribution of the total material is very similar to the one expected if all the samples had been drawn from a single panmictic population. There appears to be no association between the variation of morphological characters and that at electrophoretic loci, and this is true for the variation between as well as within samples. Data suggest that stocks either diverged rather recently or that the amount of gene flow between groups of fish classified as stocks has been large enough to prevent substantial differentiation, and that morphologic and ecologic divergence may to a large extent be environmentally induced.

Enzyme levels in pools of microdissected human muscle fibres of identified type. Adaptive response to exercise.

Abstract: Enzyme activities were determined in pools of type I (slow twitch) and II A and II B (fast twitch) fibres of the thigh muscle from individuals engaged to a high degree in physical training of an endurance character and from non-endurance-trained controls. The endurance-trained (ET) group had significantly higher activity levels of the mitochondrial enzymes citrate synthase, malate dehydrogenase, and 3-OH-acylCoA dehydrogenase both in type I (2.1X, 1.7X, 1.4X) and in type II A (2.3X, 1.8X, 1.4X) and II B fibres (2.0X, 1.5X, 1.5X) than the non-endurance-trained (NET) group. Of the glycolytic enzymes, phosphofructokinase (PFK) in type I fibres was significantly higher (1.8X) in the ET than in the NET group whereas glyceraldehydephosphate dehydrogenase (GAPDH) in type I fibres was similar in the two groups. In type II fibres both PFK and GAPDH levels tended to be higher in the ET group. Lactate dehydrogenase (LDH) of both fibre types were not different in the two groups. Type I fibres differed significantly from type II fibres for all the six enzymes measured in both groups. However, no significant difference between fibres of types II A and II B was found. The results indicate that fibres of types I, II A and II B in human skeletal muscle all possess great adaptability with regard to their oxidative capacity. Furthermore, the data suggest that extensive endurance training may enhance the glycolytic capacity in both type I and type II fibres although the glycolytic capacity of the muscle as a whole generally is low in endurance trained subjects owing to a predominance of type I fibres. It is concluded that further studies are needed to determine whether there is a metabolic distinction between fibres of types II A and II B.

Distribution of insoluble bound phenolic acids in barley grain

Abstract: Insoluble bound phenolic acids were analysed by g.l.c. and by h.p.l.c. in eight abraded fractions of barley grain. Vanillic, p-coumaric, ferulic and diferulic acids were identified in all the fractions. Ferulic and p-coumaric acids were quantitatively the most important. The outer layers, comprising husks, pericarp, testa and aleurone cells, contained the highest concentrations of total phenolic acids (0.6–0.9%) while their concentrations were considerably lower in the endosperm layers (0.1% or less). Calculated on the basis of the cell wall content in the fractions, the highest concentration of ferulic acid was found in fractions enriched with aleurone cells while the highest concentration of p-coumaric acid was found in fractions containing high levels of husks.

Different Temperature Optima for Methane Formation When Enrichments from Acid Peat Are Supplemented with Acetate or Hydrogen

Abstract: Laboratory studies of methane formation in peat samples from an acid subarctic mire in Sweden indicated the presence of a low-temperature-adapted methanogenic flora. Enrichment culture studies with ethanol, acetate, hydrogen, or a combination of these as substrate for methane formation provided evidence for the existence of two different methanogenic populations in the peat: one, unaffected by hydrogen and using acetate, with a temperature optimum at 20°C; the other, oxidizing hydrogen, with a temperature optimum at ca. 28°C.

The relative efficiency of some aphid species as vectors of potato virus Yo (PVYo)

Abstract: The relative efficiency of 7 aphid species as vectors of potato virus Yo (PVYo) was investigated. Winged aphids of one species were released in a net cage containing PVYo-infected potato plants as a virus source and healthy young potato plants as test plants. After 35 hours the glasshouse chamber was fumigated and the young plants tested for PVYo by ELISA at 10-days intervals.Myzus persicae andAcyrthosiphon pisum were the most effective vectors, infecting 26 and 25% of the test plants, respectively.Aphis fabae, Aphis nasturtii andRhopalosiphum padi infected only 1–7% test plants.Sitobion avenae andBrevicoryne brassicae did not transmit PVYo. Relative ‘efficiency factors’ are suggested from these and other results.

Photoinhibition of photosynthesis in Lemna gibba as induced by the interaction between light and temperature. I: Photosynthesis in vivo

Abstract: PHOTOINHIBITION OF PHOTOSYNTHESIS IN LEMNA-GIBBA AS INDUCED BY THE INTERACTION BETWEEN LIGHT AND TEMPERATURE .1. PHOTOSYNTHESIS INVIVO

Formation of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline in a model system by heating creatinine, glycine and glucose

Abstract: A mixture of creatinine, glucose and glycine was heated in diethylene glycol containing 14% water for 2 h at 128°C, and the mutagens formed were purified by XAD-2 column chromatography, acid-base partition, Sephadex LH-20 column chromatography, ‘blue cotton’ treatment and HPLC. Two mutagenic substances were isolated by HPLC. The major mutagen was identified by its UV absorption and mass and NMR spectra as 2-amino-3,8-dimethylimidazo[4,5- f ]quinoxaline, which was originally isolated from fried beef. This finding supported the idea that creatinine, amino acids and sugars present in meat are precursors in the formation of the mutagenic imidazoquinoxaline derivative.

Evaluation of Procedures for Scoring the Integument of Laying Hens—Independent Scoring of Plumage Condition

Abstract: A total of 4032 Single Comb White Leghorn layers were kept in six different battery cage models of different designs and feeding techniques. Indpendent scoring by two experienced observers of the same 833 birds divided into 70 groups, was used to evaluate a scoring procedure for plumage condition of hens. This consisted of a scale from 1 to 4 points for each of five parts of the body, with 4 as the maximum. These were added together to give a final total for the whole body. Comparisons between scorers were made on group means with 12 to 15 birds per group. Highly significant correlations were found between scores given by the two scorers. The average correlation coefficients for individual body parts were 0.87 (p≤0.001) and 0.94 (p≤0.001) for the whole body. Both observers ranked the average scores of the individual body parts' plumage condition in the same order. They also found the same significant differences in plumage condition between cage models. A significant tendency for one scorer to pu...

Pitfall-trap catches of the carabid beetle Pterostichus melanarius, in relation to gut contents and prey densities, in insecticide treated and untreated spring barley

Abstract: During large-scale field experiments in 1981 and 1982, designed to assess the effects of the insecticides Fenitrothion and Sumicidin (Fenvalerate) on beneficial arthropods in spring barley, significant increases in pitfall-trap catches of Pterostichus melanarius (Illiger) were observed in treated plots compared to untreated controls, several weeks after treatment. Significantly more female P. melanarius were caught in treated plots during these post-treatment increases. Corresponding decreases were observed in prey populations following treatments. Individual female P. melanarius from treated plots had significantly fewer of their gut areas full of solid (arthropod) food when compared to those from untreated control plots. Earlier workers observed both faster recapture rates in pitfalls and higher mobility in hungry carabid beetles. The following hypothesis is suggested: reducing prey populations by the application of insecticides results in hungrier carabid beetles with consequently higher activity. Since pitfall-trap catch is determined not only by population size but also activity, it is argued that pitfall-trap catches alone cannot give a true measure of the effects of insecticides on carabid populations in the field. RESUME Relations entre les captures de Pterostichus melanarius (Col; Carabidae) dans des trappes, le contenu de l'intestin, et la densite de proies, dans des parcelles d'orge de printemps traitees ou non Au cours d'essais a grande echelle, effectues en 1981 et 1982, sur orge de printemps, pour evaleur l'effet des insecticides Fenitrothion et Sumicidine (fenvalerate) sur les arthropodes utiles, un accroissement significatif des captures, dans des trappes pieges de Barber, de Pterostichus melanarius (Illiger) a ete observe plusierus semaines apres le traitement dans les lots traites par rapport aux lots temoins. Significativement plus de femelles de P. melanarius ont ete capturees dans les parcelles traitees pendant cette periode d'accroissement apres traitement. Une diminution correspondante dans les populations de proies a ete observee a la suite des traitements. Chaque femelle de P. melanarius des parcelles traitees avait une fraction significativement moins importance de son intestin remplie d'aliments solides (arthropodes) que celles des parcelles non traitees. Des auteurs precedents avaient observe des taux de capture plus rapides dans les trappes et ne plus grande mobilite des carabes affames. La reduction des populations proies par l'application d'insecticides affamerait les carabes dont l'activite serait par suite plus elevee. Comme le taux de captures dans les trappes est du a la fois a la taille de la population et a son activite, on en deduit que la capture par trappes seule ne peut donner une image exacte de l'effet des insecticides sur les populations de carabes dans les champs.

Effects of κ-casein genetic variants and lactation number on the renneting properties of individual milks

Abstract: The effects of κ-casein genetic variants, lactation number, pH and casein content on the renneting properties of individual milks were studied. Rennet coagulation time (RCT) and curd firmness were determined with the aid of a lactodynamograph and the results statistically analysed. Renneting properties were strongly related to κ-casein variants and lactation number, with κ-casein B and higher lactation numbers giving shorter RCT and increased curd firmness, the effects on curd firmness being more pronounced. The effect of κ-casein variant on RCT could be eliminated by reducing pH and adding CaCl2 to the milk samples. The effect on curd firmness was not altered by this treatment, however. The results show that the renneting properties of individual milks are to a considerable degree genetically controlled.

Areal distribution of a Neodiprion sertifer (Hym., Diprionidae) outbreak on Scots pine as related to stand condition

Abstract: Analyses of a recent N. sertifer outbreak in southern Sweden were made during on-going attack, comprising a regional and local mapping of defoliation severity, as well as a study of intensity of larval consumption, abundance of cocoons and parasitation of larvae in relation to fertilizer application. It was found that (1) the outbreak was preceded by summer and autumn droughts, (2) it was limited to infertile soils, (3) pine stands aged 20–40 yr suffered most, (4) it was less severe in trees benefiting from a reduced inter-tree competition, as measured from tree-ring growth, and (5) less severe in a fertilized stand. The findings support the hypothesis on a fundamental effect of stand nutritive state on changes in number of the sawfly.

Energy or nutrient regulation of decomposition: Implications for the mineralization-immobilization response to perturbations

Abstract: A model developed previously to describe the turnover of forest soil nitrogen is modified here to explain the effects of carbon and nitrogen additions on their dynamics. The model, which is structurally very simple, seems to explain correctly, among other phenomena, the negative correlation between N mineralization and CO2 evolution observed in many experimental situations. An important variable used to explain this behaviour is the deficiency factor, which is related to the critical C-to-nutrient ratio and which gives a measure of the C or nutrient deficiency in the substrate with respect to the needs of the decomposers. Ways are discussed in which the model output can be used to explain the observed retention in the soil of fertilizer N added to mature forest soils.

Fibre types, enzyme activities and substrate utilisation in skeletal muscles of horses competing in endurance rides

Abstract: Summary Venous blood samples and middle gluteal muscle biopsies were obtained from 21 horses taking part in 100 km or 50 km endurance rides. Group A consisted of seven horses competing over 100 km (four horses completed the ride), Group B consisted of the six horses that were among the 10 best over 50 km while the other eight horses of Group C completed 50 km at a slower speed. Blood lactate, glycerol and creatine kinase increased in all groups while aspartate aminotransferase levels were higher only in Group A. No change was found in blood glucose in Groups B and C while horses in Group A had lower levels after the ride. Neither fibre composition, fibre areas nor enzyme activities differed between the groups. Intramuscular glycogen content was similar before the ride in all groups. After the ride glycogen had decreased only half as much in Group C as compared to Groups A and B. Group C had a higher intramuscular triglyceride content at rest than Group B. The greatest decrease in triglyceride content after the ride was found in Group C. In Groups A and B many Type I, IIA and IIB fibres were glycogen depleted after the ride while in Group C mainly Type I and some Type IIA fibres were depleted. The results of this study show that intramuscular carbohydrate and lipid stores are both important fuels during endurance rides.

Nitrification and nitrogen mineralization in a lowland rainforest succession in Costa Rica, Central America

Abstract: Nitrogen availability is a critical component of productivity in successional lowland rainforests, and nitrogen losses from a given system may largely depend on rates of nitrification in soils of the system. Two hypotheses were tested in a study of a 6-point secondary rainforest sere in the coastal lowlands of Costa Rica: that nitrification and N mineralization change in a directed fashion in lowland rainforest successions, and that nitrification is regulated by ammonium availability at all points along the sere. Nitrate and mineral N production were measured in short-term laboratory incubations of soils from different stages of secondary succession corresponding to 0, 3, 8, 16, 31 and 60 + years following disturbance. Results indicate that nitrification increases through the first 4 successional stages and then declines somewhat before leveling off. In soil from all sites, most of the N mineralized was nitrified, and added NH4Cl strikingly stimulated net nitrate production. Added NaH2PO4, CaCO3, and CaSO4 did not stimulate net nitrate production or did not result in a greater proportion of nitrate than in controls. These results suggest that nitrification and N mineralization may tend to increase through secondary rainforest succession and that ammonium availability along the sere regulates rates of nitrification.

Nosema Apis, Sampling Techniques and Honey Yield

Abstract: SummaryEstimates of levels of Nosema apis infection in honeybee colonies by three different sampling and examination combinations were correlated with honey yield. Samples of 60 bees were taken in early spring in Uppsala, Sweden, live bees being taken from the cluster and dead ones from the bottom board. Parallel samples of hive bees were examined individually and compositely. Dead bees were only examined compositely. The mean spore count/bee of each composite sample was estimated with a hemacytometer. The correlation of honey yield with Nosema level was much larger for samples of live bees irrespective of counting methods, than for composite samples of dead bees. The closest correlation with honey yield (-0·707) was found for number of honeybees infected. It is concluded that when colonies are being examined in spring to determine the effects of Nosema on honey yield, it is best to sample live bees and not dead ones and to examine the bees of the samples individually rather than compositely.

Sapwood Basal Area and Needle Mass of Scots Pine ( Pinus sylvestris L.) Trees in Central Sweden

Abstract: Etablissement d'une relation entre la masse de feuillage et la surface basale de l'aubier pour un certain nombre de peuplements de pins sylvestres, test de l'adequation a une agregation des arbres echantillons a une regression avec la surface basale de l'aubier comme unique variable independante, test de la relation de la S.B.A. par unite de masse de feuillage a la largeur moyenne du cerne annuel, test de l'information sur le cerne annuel comme amelioration de la regression

Effects of a Perch in Conventional Cages for Laying Hens

Abstract: A total of 720 Single Comb White Leghorn laying hens (SCWL's Shaver 288) were studied from 22 to 82 weeks of age for the effect of a perch on production, egg weight, exterior egg quality and egg ro...

Cycling of nitrogen in modern agricultural systems

Abstract: Agro-ecosystems have developed from mixed- and multiple-cropping systems with relatively closed N cycles to intensively managed monocultures with large N inputs in the form of commercial fertilizers. Cultivation of increasingly larger areas of land has resulted in substantial losses of soil organic matter and N. Also, the move from slash and burn agriculture to intensively ploughed systems has resulted in losses through increased erosion.

Radiological investigations of osteochondrosis dissecans in Standardbred Trotters and Swedish Warmblood horses

Abstract: Summary A total of 106 Standardbred Trotters and 27 Swedish Warmblood horses, with a radiological diagnosis of osteochondrosis dissecans, were studied over a six year period. The majority were young horses. No statistical difference in frequency between the sexes was demonstrated. In both breeds osteochondrosis was most common in the hock joints, the site of predilection being the distal dorsal tip of the intermediate tibial ridge. On radiographs the lesions of the hock joints were graded on a scale from 0 to 5 according to size, number and localisation of defects and visible loose bodies. The sizes of the loose bodies estimated radiologically were fairly closely correlated with those found at surgery or autopsy.

Isolation and Characterization of Dinitrogen-Fixing Bacteria from the Rhizosphere of Temperate Cereals and Forage Grasses

Abstract: N(2)(C(2)H(2))-fixing bacteria were isolated from the rhizosphere of various cereals and forage grasses grown in the greenhouse and from the rhizosphere of field-grown wheat in Sweden. All 46 isolates from the greenhouse plants lost their nitrogenase activity during purification. By imposing a stronger selection pressure, we obtained pure isolates with nitrogenase activity from field-grown wheat. Some isolates were identified as Enterobacter agglomerans and Bacillus polymyxa, but several bacteria of uncertain taxonomy also occurred. One of the isolates grew and reduced acetylene only in the presence of other bacteria or certain vitamins. Species of Azotobacter or Azospirillum could not be isolated from the rhizosphere of any of the cereals and forage grasses studied.

Nutrient requirements and stress response of Populus simonii and Paulownia tomentosa

Abstract: The aim of this investigation was to estimate the optimum nutrient requirements and responses to low relative nutrient addition rates of seedlings of two important broadleaf tree species in China, Populus simonii Carr. and Paulownia tomentosa (Thunb.) Steud. In preliminary experiments the optimum nutrient proportions were estimated under high concentration conditions. The nutrients consumed were replaced by means of daily additions determined by pH and conductivity titrations without changing the nutrient solutions. A relatively high K level was needed in relation to nitrogen; higher than in birch or grey alder seedlings. To obtain a high relative growth rate, suitable proportions by weight were 100 N:70 K:14 P:7 Ca:7 Mg for the Populus seedlings and 100 N:75 K:20 P:8 Ca:9 Mg for the Paulownia seedlings. In studies of nutrient stress responses the relative nutrient addition rate was used as the treatment variable under low conductivity conditions. The responses and relationships were similar to those described for birch, grey alder and Salix. The relative addition rate, and there was also a strong linear regression between relative growth rate and nitrogen status. Relative growth rates were high and the maximum weight increase was about 19% day−1 in Populus and over 25% day−1 in Paulownia. The nitrogen productivity of Paulownia was very high, 0.26 g dry weight (g N)−1 h−1, and for Populus it was 0.16 g dry weight (g N)−1 h−1.