Depressed growth of non‐chlorotic vine grown in calcareous soil is an iron deficiency symptom prior to leaf chlorosis

The development of iron deficiency symptoms (growth depression and yellowing of the youngest leaves) and the distribution of iron between roots and leaves were investigated in different vine cultivars (Silvaner, Riparia 1G and SO4) grown in calcareous soils. As a control treatment all cultivars were also grown in an acidic soil. Only the cultivars Silvaner and Riparia 1G showed yellowing of the youngest leaves under calcareous soil conditions at the end of the cultivation period. All cultivars including SO4 showed severe shoot growth depression, by 50 % and higher, before yellowing started or without leaf yellowing in the cultivar SO4. Depression of shoot growth occurred independently from that of root growth. In a further treatment the effect of Fe‐EDDHA spraying onto the shoot growth of the cultivar Silvaner after cultivation in calcareous soil was investigated. Prior to Fe application plants were non‐chlorotic, but showed pronounced shoot growth depression. Spraying led to a significant increase in shoot length, though leaf growth was not increased. Accordingly, depression of shoot growth of non‐chlorotic plants under calcareous soil conditions and with ample supply of nutrients and water has been evidenced to be at least partly an iron deficiency symptom. We suggest that plant growth only partially recovered because of dramatic apoplastic leaf Fe inactivation and/ or a high apoplastic pH which may directly impair growth. Since growth was impaired before the youngest leaves showed chlorosis we assume that meristematic growth is more sensitively affected by Fe deficiency than is chlorophyll synthesis and chloroplast development. In spite of high Fe concentrations in roots and leaves of the vines grown in calcareous soils plants suffered from Fe deficiency. The finding of high Fe concentrations also in young, but growth retarded green leaves is a further indication that iron deficiency chlorosis in calcareous soils is caused by primary leaf Fe inactivation. However, in future, only a rigorous study of the dynamic changes of iron and chlorophyll concentration, leaf growth and apoplastic pH at the cellular level during leaf development and yellowing will provide causal insights between leaf iron inactivation, growth depression, and leaf chlorosis.<?show $6#>     

Priming effects of sugars,amino acids,organic acids and catechol on the mineralization of lignin and peat

The ¹⁴C‐labeled substrates glucose, fructose, alanine, glycine, oxalic acid, acetic acid, and catechol were incubated at 20 °C in a model system that consisted of sand mixed with lignin or peat (3 % C_org). Each substrate was added at either 80 or 400 μg C (g sand)^—1. During 26 days of incubation with an inoculum extracted from forest soil, the amount of CO₂ evolved was measured hourly. The amount of ¹⁴CO₂ was determined after 4, 6, 12, 19, and 26 days. After 26 days of incubation, each substrate showed priming effects, but not in all examined treatments. Most substrates stimulated the degradation of the model substances (positive priming effects). Negative priming effects only were found in the lignin system with oxalic acid and catechol addition at both concentrations. The strongest positive priming occurred in the peat system with the oxalic acid addition of 80 μg C g^—1 where 1.8 % of the peat were mineralized after 26 days, compared to 0.7 % in the control. The addition of 400 μg alanine‐C g^—1 caused the strongest increase in lignin mineralization, amounting to 3.9 % compared to 2.8 % in the control. During the incubation the extent of priming changed with time. Most substrates caused the strongest effects during the first 4 to 10 days of incubation. The extent of priming depended on substrate type, substrate concentration, and organic model substance. Possibly this is due to the activation of different microorganisms.     

Molecular characterization of PRR13 and its tissue-specific expression in rainbow trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>)

The proline-rich protein 13 (PRR13) is reported to be a key regulator of the resistance to cytostatica by decreasing the copy number of the proapoptotic gene thrombospondin-1. We isolated and characterized the complete PRR13 gene sequence of rainbow trout (Oncorhynchus mykiss). The gene comprises four exons and three introns, the latter of comparatively short lengths (100–811 bp). The full-length PRR13 cDNA consists of 1,101 nucleotides, including an open reading frame of 563 bp, which is predicted to encode a 187 amino acid protein with a molecular mass of 18.8 kDa. A continuous stretch of ten serine residues at the C-terminus is highly conserved and characteristic for vertebrate PRR13, but not for other known proline-rich proteins. Phylogenetic analyses suggest a clear separation of teleostean PRR13 proteins and those from mammalian and reptilian species. Comparison of the tissue-specific PRR13 mRNA abundance in two strains of the rainbow trout coastal form (TCO Steelhead II-WA vs. BORN Steelhead II-Germany) revealed an increased expression in the BORN trout in nearly all examined tissues. The major expression differences were detected in gill (2.29-fold) and in liver tissue (2.16-fold). Hence, the increased PRR13 expression in BORN trout might cause improved protection from natural cytostatica and therefore support our assumption that PRR13 is a candidate gene possibly involved in the varying ability of the two rainbow trout strains to handle environmental stress under local conditions of the Southern Baltic.     

Effect of extreme acid and alkali treatment on surface properties of soils

Effects of natural or anthropogenic soil acidification and alkalization on chemical or biological properties have been studied extensively while little is known about changes in physicochemical characteristics, such as surface area or adsorption energy. To investigate this, samples of six Polish soils (Inceptisols, Mollisols) and three Korean soils (Alfisols, Ultisols) of different origin and mineral composition were acidified and alkalized with elevated concentrations of hydrochloric acid and sodium hydroxide ranging from 0.001 to 1 mol dm^—3. Surface properties of these soils were studied. The surface area and average adsorption energy decreased in general in both treatments. The treatments induced the decrease in amount of high and medium energy centers, however the fraction of low energy centers increased. The behavior of surface properties differed from the above at treatments at highest reagent concentrations, especially for Korean soils, rich in clay and iron oxides. The general pattern of the adsorption energy decrease observed in most of the soils indicates that the overall water binding forces become lower after treatments. In this case the soil water may be more available for plants, despite its amount decreases.     

Sorption von polyzyklischen aromatischen Kohlenwasserstoffen (PAK) und polychlorierten Biphenylen (PCB) im Boden

Sorption of polycyclic aromatic hydrocarbons (PAH) and polychlorinated biphenyls (PCB) in soil Hydrophobic organic compounds such as PAH and PCB in soils are mainly sorbed to organic matter. There exist several conceptual models about the sorption mechanisms which encompass covalent bonds, hydrophobic interactions and diffusion-controlled partitioning. The partitioning of hydrophobic compounds into the aqueous phase can be enhanced through sorption to dissolved organic matter (DOM). For such 3-phase systems, some model calculations are presented in order to evaluate the mobilizing potential of DOM. Many investigations show that the sorptivity of organic matter is influenced by certain quality parameters such as aromaticity and molecular size. In addition, it can be modified by the chemical environment (pH, salts). But despite the progress made in the last years in the understanding of these relationships there remains a multitude of open questions and further research needs.