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We studied freshly collected, dried and herbarized leaf fragments of two palms, namely Borassus flabellifer L. and Corypha umbraculifera L., most commonly used for palm-leaf manuscript (PLM) production in South (S) and Southeast Asia (SE) in order to reveal differences in their phytolith assemblages. For each of the two palms, 25 leaf samples were taken from the two Indian states of Kerala and Tamil Nadu. Dried leaf material was obtained from the fresh one by drying the leaves in air. Herbarium samples were obtained from two independent herbaria, specimen origin comprises S and SE Asia with the main focus on South India and Sri Lanka. Additionally, 25 manuscripts made of Borassus flabellifer leaves and 25 manuscripts made of Corypha umbraculifera leaves were investigated for phytoliths. All manuscripts are preliminary dated back to between the 16th and the beginning of the 20th century CE; most of them assumedly were produced in S India (Tamil Nadu and Kerala), Sri Lanka, Burma or Indonesia. Phytolith assemblages significantly differed between fresh, dry and herbarized palm leaves in comparison to PLM material, both qualitatively and quantitatively (mean r2 = - 0.61 ± 9.3 for Borassus samples and r2 = - 0.75 ± 5.3 for Corypha samples, at p < 0.001). Fifty-three phytolith types described for PLM material were not observed in any of the fresh, dry or herbarized palm-leaf samples. Geographical analysis of PLM-specific phytoliths suggests that the combination of those phytoliths could be region-related. In this paper, we prove that the methods of palaeoecological reconstructions based on detailed microscopy of the PLMs surface and phytolith analysis applied in combination with methods of mathematical and computer data analysis can contribute to answer the questions posed by material codicology by revealing lost manuscript production recipes and by studying manuscript provenance in terms of the geographical origin of the artefacts. Our approach can potentially open a new perspective for palaeoecological studies expanding their traditional scope and making them applicable to a new research field. [ABSTRACT FROM AUTHOR]

Potassium is the most abundant cation in higher plants and essential for various physiological processes like enzyme activation, phloem transport and maintenance of cellular cation:anion balance. In addition, it mediates stomatal movements and osmoregulation during cell expansion. The uptake and transport mechanisms of potassium have been studied in detail in herbaceous species by various groups. After taken up by the roots, potassium is transported via the xylem towards the leaves, where it can be used metabolically or be loaded into the phloem and translocated to different sinks like young leaves, fruits and roots as well as developing wood. In contrast to herbaceous species our knowledge of potassium functions in trees is still incomplete and mainly focused on fertilization effects on phenological growth parameters. With regard to wood formation, previous work on spruce trees revealed a distinct correlation between potassium and cambial growth activity (Dünisch and Bauch 1994, Dünisch et al. 1998). In poplar, an important tree species in the field of wood biotechnology, we studied the role of potassium during xylogenesis and found a close correlation between cambial potassium content, osmotic potential and cambial activity (Wind et al. 2004). All parameters increased from spring to summer and decreased from summer to autumn. When poplar trees were grown under low potassium regimes, the cambial activity as well as the seasonal rate of wood increment and the vessel lumen were significantly reduced. Apart from the anatomical aspects the molecular and electrophysiological basis of potassium-dependent xylogenesis has been studied (Langer et al. 2002), indicating a strong involvement of specific ion channels. Two K+ ion channels, PTK2 and PTORK, have been identified and shown to correlate with seasonal wood production. While PTK2 carries inward K+ flux at hyperpolarized membrane potential and K+ release upon depolarization, PTORK mediates potassium release upon depolarization (Langer et al. 2002). Antibodies raised against PTORK recognized this channel in growth active trees only (Arend et al. 2005). PTORK labelling was found in young fibers of the developing wood and in ray parenchyma cells of mature wood. In the latter, it might be required for charge balance during uptake of metabolites from the vessels, whereas in differentiating fibers PTORK might be involved in the reduction of protoplast volume. Taken together, it can be concluded that potassium plays a key role in the regulation of wood formation. References Arend M., Stinzing A., Wind C., Langer K., Latz A., Ache P., Fromm J., Hedrich R. 2005. Polar-localised poplar K+ channel capable of controlling electrical properties of wood-forming cells. Planta 223: 140-148 Dünisch O., Bauch J. 1994. Influence of mineral elements on wood formation of old growth spruce (Picea abies L. Karst.). Holzforschung 48: 5-14 Dünisch O., Bauch J., Müller M., Greis O. 1998. Subcellular quantitative determination of K and Ca in phloem, cambium and xylem cells of spruce (Picea abies L. Karst.) during earlywood and latewood formation. Holzforschung 52: 582-588 Langer K., Ache P., Geiger D., Stinzing A., Arend M., Wind C., Regan S., Fromm J., Hedrich R. (2002) Poplar potassium transporters capable of controlling K+ homoeostasis and K+ dependent xylogenesis. The Plant Journal 32: 997-1009 Wind C., Arend M., Fromm J. 2004. Potassium-dependent cambial growth in poplar. Plant Biology 6: 30-37

Juvenile Eucalyptus grandis were exposed to drought and elevated CO2 to evaluate the independent and interactive effects on growth, gas exchange and wood structure. Trees were grown in a greenhouse at ambient and elevated CO2 (aCO2, 410 ppm; eCO2, 950 ppm), in combination with daily irrigation and cyclic drought during one growing season. The results demonstrated that drought stress limited intercellular CO2 concentration, photosynthesis, stomatal conductance, and transpiration, which correlated with a lower increment in height, stem diameter and biomass. Drought also induced formation of frequent and narrow vessels accompanied by a reduction in vessel lumen area. Conversely, elevated CO2 increased intercellular CO2 concentration as well as photosynthesis, and partially closed stomata, leading to a more efficient water use, especially under drought. There was a clear trend towards greater biomass accumulation at eCO2, although the results did not show statistical significance for this parameter. We observed an increase in vessel diameter and vessel lumen area at eCO2, and, contrarily, the vessel frequency decreased. Thus, we conclude that eCO2 delayed the effects of drought and potentialized growth. However, results on vessel anatomy suggest that increasing vulnerability to cavitation due to formation of larger vessels may counteract the beneficial effects of eCO2 under severe drought. [ABSTRACT FROM AUTHOR]