Impacts of soil conditions and light availability on natural regeneration of Norway spruce <Emphasis Type="Italic">Picea abies</Emphasis> (L.) H. Karst. in low-elevation mountain forests

? Key message

Natural regeneration of P. abies (L.) H. Karst. may reach high densities in lower mountain elevations. The highest densities were found in sites with moderate light availability, with low pH, and not near the riverbank. However, age-height classes differed in the predicted magnitude of response, but were consistent in response directions. Mosses and understory species typical of coniferous forests were positively correlated with regeneration density.

? Context

Norway spruce Picea abies (L.) H. Karst. in Central Europe is at risk under climate change scenarios, particularly in mountain regions. Little is known about the impact of environmental factors on the natural regeneration of P. abies in low-elevation mountain forests.

? Aims

We aimed to assess impacts of distance from the riverbank, soil pH, and light availability on natural P. abies regeneration. We hypothesized that (1) natural P. abies regeneration would depend on light availability and soil pH and (2) there are understory plant species which may indicate the microsites suitable for natural regeneration of P. abies.

? Methods

The study was conducted in the Sto?owe Mountains National Park (SW Poland, 600–800 m a.s.l.). We established 160 study plots (25 m²) for natural regeneration, light availability, soil pH, and understory vegetation assessment.

? Results

The highest densities of natural regeneration of P. abies were observed in sites with moderate light availability (0.1–0.2 of open sky) and low pH (3.5–4.5), and located relatively far from the riverbank. Cover of 22 understory plant species were correlated with natural P. abies regeneration densities, mostly positively.

? Conclusion

Different stages of natural regeneration of P. abies revealed different regeneration niches. Most understory plant species (bryophytes and herbs typical of coniferous forests) do not compete with natural regeneration of P. abies.

     

Growth in juvenile pikeperch (Sander lucioperca L.) stimulated with yeast,Saccharomyces cerevisiae,extract

Thanks to the content of valuable bioactive substances, yeast, Saccharomyces cerevisiae, is finding wider applications in aquaculture and marine fish husbandry. Highly bio‐available and bio‐assimilable yeast extracts, which are obtained through processes that remove cell walls, are of special interest. The current study examined the impact of yeast extracts added to commercial feed at concentrations of 2% (group F2), 4% (group F4) and 6% (group F6) on growth, blood biochemistry parameters, liver and intestinal morphology, proximate body composition and the content of free amino acids in the muscle tissues of European pikeperch, Sander lucioperca (initial body weight = 10 g). At the termination of the experiment that ran for 60 days, the highest increases in body weight were noted in all the groups of fish that had received yeast extract (final body weight ≈ 35 g vs. control group ≈ 31 g). The daily and specific growth rates indexes were the highest in group F6. The alanine aminotransferase activity in this group was half of that in the control group (group C) (p < .05). The lowest levels of plasma bilirubin were noted in groups F4 and F6, while these groups had the highest hepatosomatic indexes that differed significantly to those of group C (p < .05). Microscopic analysis of the intestines indicated significant growth in the enterocyte height and supranuclear zone, or the so‐called absorption space, as the quantity of yeast extract added to the diets increased. Yeast supplementation was not noted to have a significant impact on the proximate body composition or the contents of free amino acids in the fish muscle tissues. In conclusion, the lowest analysed dose of yeast (i.e. 2% yeast extract) stimulates the growth of pikeperch.     

The origin of clones among androgenic regenerants of hexaploid triticale

Doubled haploids (DH) have become a standard tool in breeding and genetic studies of many crops and in most cases androgenesis is the only available route of their production. It has been recently observed that some populations of DH lines obtained via androgenesis contain high proportions of clones. This seriously reduces the efficiency of breeding and may jeopardize genetic studies. This study was designed to determine at which stage of androgenesis these clones are created, using samples set aside during routine production of DH lines in breeding of hexaploid triticale. The fate of each androgenic structure was carefully followed through the entire regeneration process, and all obtained plants were genotyped using DNA markers. Overall, 189 plants were regenerated forming 33 families, each originating from a single original androgenic structure (callus, polyembryos). In ca. 80 % of cases all members of a family were genetically identical. However, in about 20 % of cases the families of regenerants were genetically heterogeneous, showing that not all androgenic structures originate from single microspores. The evidence shown here demonstrates that retention of single plants from each original structure guarantees the production of only unique genotypes but it reduces the total output of plants. If maximum output is desired, multiple regenerants from single callus can be retained but must be genotyped using at least 10 polymorphic markers to identify clones.     

Procyanidin oligomers from Japanese quince (Chaenomeles japonica) fruit inhibit activity of MMP-2 and MMP-9 metalloproteinases

The influence of procyanidin extract from Japanese quince fruit on the activities of matrix metalloproteinases MMP-2 and MMP-9 secreted to culture medium by human peripheral blood mononuclear cells (PBMC) and by human leukemia HL-60 cells was investigated by gelatin zymography. The extract proved to be an effective inhibitor of the enzymes activities (for MMP-2 and MMP-9 secreted by PBMC IC50 = 16-19 microg extract/mL and 22-25 microg extract/mL, respectively). To identify the most effective components of the extract it was fractionated by means of column chromatography on TSKgel Toyopearl HW-40 (S) bed. The obtained fractions were analyzed by TLC, HPLC, and MALDI-TOF MS. Their antioxidant activity was measured as cation radicals ABTS(.+) scavenging efficiency. The fractions VIII-XIV containing oligomers from trimer to hexamer (and probably higher oligomers) appeared to be the most effective inhibitors of MMP-2 and MMP-9 activity (IC50 value close to 4.6 microg total polyphenols/mL). To the best of our knowledge, it is the first report on gelatinase-inhibitory activity of Japanese quince fruit polyphenol extract. We conclude that polyphenols from Japanese quince can be used in cancer chemoprevention, although further studies are needed to elucidate the mechanisms underlying their biological activities.     

Abundance and control of Lygus rugulipennis (Heteroptera: Miridae) on Scots pine (Pinus sylvestris L.) nursery stock

Population fluctuations of the European tarnished plant bug (Lygus rugulipennis Popp.) on nursery-grown Scots pine, Pinus sylvestris L. were monitored with sweep net samples over five growing seasons. The effects of cypermethrin, lindane and oxydemetonmethyl insecticide sprayings on the occurrence of Lygus adults and nymphs and prevalence of bud disorders of pine seedlings were studied. The number of Lygus bugs was highest in 1984, the first year of the study, and thereafter the annual levels of the bug declined, reaching a low in 1988. On 2- and 3-year-old Scots pine seedlings the numbers of overwintered L. rugulipennis adults and nymphs correlated positively with the occurrence of abnormal buds. Cypermethrin sprayings significantly reduced the numbers of Lygus nymphs in 1985 and 1987. In 1986 significantly fewer damaged seedlings and L. rugulipennis adults were found in pine transplants treated with cypermethrin.     

Tannic acid and Norway spruce condensed tannins can precipitate various organic nitrogen compounds

There is increasing evidence that tannins affect degradation of soil organic matter and nitrogen cycling. It is assumed that the influence of tannins on biochemical processes is partly related to their ability to precipitate proteins. However, there is almost no information about precipitation of organic nitrogen-containing compounds other than proteins. A few studies indicate that tannins can precipitate arginine, choline or chitosan. In this study we used commercial tannic acid and condensed tannins extracted from Norway spruce (Picea abies (L.) Karst) needles to investigate precipitation of a wide range of organic nitrogen compounds including amino acids (all 20 proteinaceous), peptides (insulin, oxidized glutathion, reduced glutathion, AlaAla, GlyGlu, GlyPhe, GlyGlyGly), proteins (bovine serum albumin, Rubisco i.e. d-ribulose 1,5-diphosphate carboxylase), nitrogen bases, polyamines and aminosugars (N-acetyl-d-glucosamine, chitin and chitosan). Our results showed that tannins can precipitate a subset of these compounds - of the amino acids only arginine, of the peptides studied only insulin, all the proteins, polyamines, nitrogen bases, chitin and chitosan, but not N-acetyl-d-glucosamine. Concentrations of organic nitrogen compound and tannins affected amount of these compounds in precipitates. Moreover, pH value affected precipitation. The amount of precipitated organic nitrogen compound and the amount of precipitated tannins showed positive correlation across different pH. Precipitation of organic N-containing compounds other than protein by tannins can potentially affect reactions in all biochemical mixtures including tannins and these organic nitrogen compounds, and affect soil N cycling.     

Influence of diterpenes (colophony and abietic acid) and a triterpene (beta-sitosterol) on net N mineralization,net nitrification,soil respiration,and microbial biomass in birch soil

The aim of this study was to examine the effect of common diterpenes (colophony, abietic acid) and triterpene (beta-sitosterol) on carbon (C) and nitrogen (N) transformations in soil under birch (Betula pendula L.). Samples were taken from the organic layer at two study sites, Kivalo (N-poor soil) and Kerimäki (N-rich soil), and incubated with the above-mentioned terpenes in laboratory conditions. Carbon dioxide evolution (C mineralization), net N mineralization, nitrification, and N and C in microbial biomass were measured. All these terpenes increased C mineralization, but decreased net N mineralization. The potential to decrease net N mineralization depended on amount of terpenes, with a stronger effect at a higher amount. Net nitrification in Kerimäki soil (N-rich soil) decreased but was not completely inhibited by terpenes. Effect of terpenes on soil microbial biomass C and N was not so clear, but they tended to increase both. Our study suggests that higher terpenes can act as a carbon source for soil microbial communities.