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Effects of manganese toxicity on photosynthesis of white birch (Betula platyphylla var. japonica) seedlings 总被引:5,自引:0,他引:5
The effects of manganese (Mn) toxicity on photosynthesis in white birch ( Betula platyphylla var. japonica ) leaves were examined by the measurement of gas exchange and chlorophyll fluorescence in hydroponically cultured plants. The net photosynthetic rate at saturating light and ambient CO2 (Ca ) of 35 Pa decreased with increasing leaf Mn concentrations. The carboxylation efficiency, derived from the difference in CO2 assimilation rate at intercellular CO2 pressures attained at Ca of 13 Pa and O Pa, decreased with greater leaf Mn accumulation. Net photosynthetic rate at saturating light and saturating CO2 (5%) also declined with leaf Mn accumulation while the maximum quantum yield of O2 evolution at saturating CO2 was not affected. The maximum efficiency of PSII photochemistry (Fv /Fm ) was little affected by Mn accumulation in white birch leaves over a wide range of leaf Mn concentrations (2–17 mg g−1 dry weight). When measured in the steady state of photosynthesis under ambient air at 430 μmol quanta m−2 s−1 , the levels of photochemical quenching (qP) and the excitation capture efficiency of open PSII (F'v /F'm ) declined with Mn accumulation in leaves. The present results suggest that excess Mn in leaves affects the activities of the CO2 reduction cycle rather than the potential efficiency of photochemistry, leading to increases in QA reduction state and thermal energy dissipation, and a decrease in quantum yield of PSII in the steady state. 相似文献
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We studied topographical and year-to-year variation in the performance (pupal weights, survival) and larval parasitism of
Epirrita autumnata larvae feeding on mountain birch in northernmost Finland in 1993–1996. We found differences in both food plant quality and
parasitism between sites ranging from 80 m to 320 m above sea level. Variation in food plant quality had particularly marked
effects on larval survival. The advanced phenology of the birches in relation to the start of the larval period reduced pupal
weights. Parasitism rates were different between years and between sites. The clearest site differences were in the proportions
of different parasitoid species: Eulophus larvarum was most abundant at the lowest-altitude sites, and Cotesia jucunda at the highest. Differences in the performance of E. autumnata were related to temperature conditions: at higher temperatures, survival and the egg production index were lower, and larval
parasitism was higher than at lower temperatures. The higher parasitism at higher temperatures was probably due to greater
parasitoid activity during warmer days. In the comparison of different sources of spatial and annual variation in the performance
of E. autumnata, the most important factor appeared to be egg mortality related to minimum winter temperature, followed by parasitism and,
finally, the variation in food plant quality. If, as predicted, the climate gradually warms up, the effects of warmer summers
on the outbreaks of E. autumnata suggest a decrease in outbreak intensity.
Received: 4 January 1999 / Accepted: 22 March 1999 相似文献
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The effects of nitrogen (N) fertilisation and elevated [CO2] on lipid biosynthesis and carbon isotope discrimination in birch (Betula pendula Roth.) transplants were evaluated using seedlings grown with and without N fertiliser, and under two concentrations of atmospheric
CO2 (ambient and ambient+250 μmol mol-1) in solar dome systems. N fertilisation decreased n-fatty acid chain length (18:0/16:0) and the ratios of α-linolenate (18:2)/linoleate (18:1), whereas elevated [CO2] showed little effect on n-fatty acid chain length, but decreased the unsaturation (18:2+18:1)/18:0. Both N fertilisation and elevated [CO2] increased the quantity of leaf wax n-alkanes, whilst reducing that of n-alkanols by 20–50%, but had no simple response in fatty acid concentrations. 13C enrichment by 1–2.5‰ under N fertilisation was observed, and can be attributed to both reduced leaf conductance and increased
photosynthetic consumption of CO2. Individual n-alkyl lipids of different chain length show consistent pattern of δ13C values within each homologue, but are in general 5–8‰ more depleted in 13C than the bulk tissues. Niether nitrogen fertilisation and elevated CO2 influenced the relationship between carbon isotope discrimination of the bulk tissue and the individual lipids.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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Fourteen morphometric variables of silver birch (Betula pendula Roth) leaves from two sites in the Upper Silesia province were analyzed to establish the pattern of intrapopulational and interpopulational relations. The leaves were collected from ten trees growing on a zinc–lead dump as well as from ten trees in the unpolluted area of Mirów within the same bioclimatic region. Leaf samples were collected from the trees during the vegetative seasons 1999 and 2000. The size and shape of leaves were studied using standard biometric methods. Cluster analysis indicated overall differences between the populations. Both populations differed with respect to almost all the morphometric variables (P<0.05). Most variables of the leaves, collected from single trees (or combined as a total) on the zinc–lead dump showed more variability than those from the unpolluted site. Discriminant function analysis confirmed the angle of the leaf base as the most important variable in the evaluation of interpopulational variability of leaves. 相似文献
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