Effects of soil moisture manipulations on fine root dynamics in a mature balsam fir (Abies balsamea L. Mill.) forest

We tested the hypothesis that moisture stress affects fine root dynamics during and after the stress. To this end, we investigated the effects of soil moisture on annual and seasonal fine root production and mortality over 4 years in a mature balsam fir (Abies balsamea L. Mill.) stand using a minirhizotron and soil coring. Droughting and irrigating treatments were imposed for 17 weeks during the third year of the study, and post-treatment recovery was measured during the fourth year. Monthly fine root production was often reduced by low soil water content (SWC) during July-September in the pre-treatment years and by imposed drought. Irrigation resulted in higher summer fine root production than in pre-treatment years. In the recovery year, increased fine root production was observed in the previously droughted plots despite low SWC in August and September. Droughting decreased year-end fine root biomass in the treatment year, but biomass returned to pre-treatment levels during the recovery year. Droughting and irrigating did not affect foliage production during the treatment and recovery years. Our results suggest that for balsam fir, establishment and maintenance of a functional balance between foliage and fine root biomass, with respect to moisture supply and demand, can depend on fine root dynamics occurring over more than one growing season. In addition, our findings provided insights into tree growth responses to interannual variation in moisture supply.     

Environmental mycobacteria closely related to the pathogenic species evidenced in an acidic forest wetland

The diversity of environmental mycobacteria was studied in water-logged acidic forest soil. Mycobacteria were assessed in upper and lower soil horizons and summer and winter seasons using T-RFLP and sequencing of 16S rRNA gene produced with Mycobacterium-specific primers. Mycobacteria diversity differed between both the two seasons and soil horizons. Cloning revealed the presence of mycobacteria belonging to three major clusters recognized within the genus, i.e. fast-growing, intermediate, and slow-growing species, with unprecedented abundance and diversity of the latter. Two novel clusters of sequences unrelated to the known mycobacteria were identified. This study raises the possibility that forest wetlands could serve as environmental reservoirs for an unexplored diversity of mycobacteria including those related to pathogenic species.     

Distribution of polycyclic aromatic hydrocarbons (PAHs) in the bottom sediments of a dam reservoir,their interaction with organic matter and risk to benthic fauna

Journal of Soils and Sediments - The aims of the study were to investigate the interaction between fractions of organic matter and polycyclic aromatic hydrocarbons (PAHs) in bottom sediments and to...     

The Presence of Nitrates and the Impact of Ultraviolet Radiation as Factors that Determine Nitrate Reductase Activity and Nitrogen Concentrations in Deschampsia antarctica Desv. Around Penguin Rookeries on King George Island,Maritime Antarctica

This paper addresses the oxidation by ultraviolet radiation of methylparaben, a ubiquitous and suspicious preservative which is massively added to cosmetics and personal care products. Experiments included pH and temperature variation, as well as several experimental conditions such as presence/absence of hydrogen peroxide, titanium dioxide, or some different water matrix (surface water or ground water). Results were evaluated under the line source spherical emission model, so quantum yield was the adequate target variable for explaining the process. A modified Arrhenius correlation including pH level was used for modelling the whole system.     

Testing of performance in common carp Cyprinus carpio L. under pond husbandry conditions I: top-crossing with Northern mirror carp

Performance tests of Northern mirror carp (M72) and three different crossbreds were conducted in semi‐intensive pond conditions from the larval stage up to market size. The aim of this study was to evaluate the possible utilization of new hybrid combinations (M72 × PL – Poho?elice mirror carp) and (M72 × Dor – Israeli mirror carp), and to compare them with a hybrid widely reared as a commercial product (M72 × M2 – Hungarian mirror carp) and with M72 purebred. The testing model was derived from similar studies carried out in the conditions of the Czech Republic, where an internal control of different scale cover is used to eliminate all non‐genetic effects. ancova revealed at market size significantly better growth in M72 × Dor (1 619±28.3 g; LS mean±SE) and M72 × PL (1475±29.8 g) compared with M72 (1278±26.3 g). Survival during the test of 3 years duration was significantly the best in the M72 × Dor hybrid as were the dressing out parameters measured at market size, even if these were significantly different only in proportion of fillets with skin (39.1±0.28%). Interestingly, the crossbred M72 × M2 commonly used by Czech fishermen showed for both, growth (1371±26.2 g) and survival, the lowest values among crossbreds and with regard to dressing out parameters mostly among all tested groups.     

Studies on sperm of diploid and triploid tench, Tinca tinca (L.)

The tench Tinca tinca is an interesting fish from the viewpoint of polyploidy and related atypical reproduction aspects. Triploid tench were produced artificially. Studies of spermiation as well as of sperm motility and structure were performed on several triploid and diploid males simultaneously with individual experimental crosses with diploid females to define their reproductive capacities. The testes of triploids visually looked less developed in the most of cases with lower sperm production (0.05 cm³ sperm per male), GSI and weight of testes compared to diploids (0.58 cm³ sperm per male). Analysis of variance showed significant influence of ploidy level on the percentage of motile spermatozoa. Triploidy did not change percentage of live spermatozoa and velocity of spermatozoa at the first time of sperm movement. The study of sperm structure by scanning electron microscopy revealed that most sperm cells were of normal structure with some anomalies. Sperm heads of triploid and diploid males were mostly round-shaped, 1.86±0.2 and 1.6±0.18 μm in diameter. The midpiece of triploid spermatozoa was slightly narrower than that of diploid ones with typical cylindrical shape. Flow cytometry revealed sperm cells of triploids to be largely aneuploid (1.47 n) with high mosaic DNA, oscillating from haploid DNA content (1.0 n) to diploid DNA content (1.9 n). Experimental crosses between triploid males and diploid females revealed that these males were capable to stimulate effective development with relatively high level of fertilization and hatching rates from 0 to 70%. In conclusion, triploidization does not seem to guarantee sterility of tench.     

Chemical composition of French and Polish cloudy apple juices

Summary

Cloudy juices from six apple cultivars from Poland (‘Ariwa’, ‘Gold Milenium’, ‘Florina’, ‘Melfree’, ‘Novamac’, and ‘Rajka’) and four French cultivars (‘Ariane’, ‘Chanteline’, ‘Judeline’, and ‘Judor’) were produced and chemically characterised. The analyses encompassed 23 chemical parameters and phenolics profiles. The most important parameter, differentiating cloudy juice from clear juice, was turbidity. Cloudy juices were characterised by having an average total turbidity of 1,210 Nephelometric Turbidity Units (NTU) and a stability of turbidity of 42%. Some of the results deviated from the accepted ranges given in reference values for apple juices in the Code of Practice of the European Fruit Juice Association. This occurred in the cases of simple sugars and saccharose contents of the Polish apple juices (e.g., up to 56.9 mg l^–1 of saccharose vs. a maximum value of 30 mg l^?1), and for some mineral compounds in the French apple juices (e.g., sodium values up to 10 mg l^?1). Large variations were found in case of important healthconferring components. Water-soluble pectin contents varied from 205 mg l^?1 for ‘Chanteline’, to 1,289 mg l^?1 for ‘Gold Milenium’; while, in the case of phenolic compounds, the range was from 85.7 mg l^?1 for ‘Novamac’, to 524.8 mg l^?1 for ‘Melfree’.