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  • 1
    ISSN: 1432-2285
    Keywords: Scots pine ; Aluminum ; Pollution ; Photosynthesis ; Roots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract One-year-old Scots pine (Pinus sylvestris L.) seedlings were grown for 9 weeks in nutrient solutions containing 0, 0.5, 1, 2 and 4 mM aluminum nitrate (Al(NO3)3) at pH 4.2. Nine weeks exposure to Al significantly reduced total plant, shoot and root mass and caused a linear decline in proportional allocation of biomass to roots. Relative growth rate of roots declined to as low as zero. Aluminum treatment decreased calcium and magnesium uptake and increased Al content in roots and needles. After 3 weeks of exposure a 10–60% increase in total phenols in roots and a 20–40% increase in o-diphenols in roots and needles were noted. Roots affected by Al showed degeneration of meristematic cells, fewer cell divisions, deformation in cell walls and higher lignification and suberization. The majority of root apices were structurally similar to dormant roots, and a premature senescence of the entire root system was observed. Net photosynthetic rate after 6 weeks of treatment was negatively correlated with needle Al content and Al/Ca ratio (r 〈 -0.9, P 〈 0.1). The results suggest that Scots pine may be more susceptible to Al than was expected based on previous experiments.
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  • 2
    ISSN: 0931-1890
    Keywords: Key words Scots pine ; Aluminum ; Pollution ; Photosynthesis ; Roots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  One-year-old Scots pine (Pinus sylvestris L.) seedlings were grown for 9 weeks in nutrient solutions containing 0, 0.5, 1, 2 and 4 mM aluminum nitrate (Al(NO3)3) at pH 4.2. Nine weeks exposure to Al significantly reduced total plant, shoot and root mass and caused a linear decline in proportional allocation of biomass to roots. Relative growth rate of roots declined to as low as zero. Aluminum treatment decreased calcium and magnesium uptake and increased Al content in roots and needles. After 3 weeks of exposure a 10 – 60% increase in total phenols in roots and a 20 – 40% increase in o-diphenols in roots and needles were noted. Roots affected by Al showed degeneration of meristematic cells, fewer cell divisions, deformation in cell walls and higher lignification and suberization. The majority of root apices were structurally similar to dormant roots, and a premature senescence of the entire root system was observed. Net photosynthetic rate after 6 weeks of treatment was negatively correlated with needle Al content and Al/Ca ratio (r 〈  – 0.9, P 〈 0.1). The results suggest that Scots pine may be more susceptible to Al than was expected based on previous experiments.
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  • 3
    ISSN: 0931-1890
    Keywords: Key words Betula pendula ; Photosynthesis ; Respiration ; Nutrients ; Leaf ontogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  In order to explore ontogenetic variation in leaf-level physiological traits of Betula pendula trees, we measured changes in mass- (A mass) and area-based (A area) net photosynthesis under light-saturated conditions, mass- (RSmass) and area-based (RSarea) leaf respiration, relative growth rate, leaf mass per area (LMA), total nonstructural carbohydrates (TNC), and macro- and micronutrient concentrations. Expanding leaves maintained high rates of A area, but due to high growth respiration rates, net CO2 fixation occurred only at irradiances 〉200 µmol photons m–2 s–1. We found that full structural leaf development is not a necessary prerequisite for maintaining positive CO2 balance in young birch leaves. Maximum rates of A area were realized in late June and early July, whereas the highest values of A mass occurred in May and steadily declined thereafter. The maintenance respiration rate averaged ≈8 nmol CO2 g–1 s–1, whereas growth respiration varied between 0 and 65 nmol CO2 g–1 s–1. After reaching its lowest point in mid-June, leaf respiration increased gradually until the end of the growing season. Mass and area-based dark respiration were significantly positively correlated with LMA at stages of leaf maturity, and senescence. Concentrations of P and K decreased during leaf development and stabilized or increased during maturity, and concentrations of immobile elements such as Ca, Mn and B increased throughout the growing season. Identification of interrelations between leaf development, CO2 exchange, TNC and leaf nutrients allowed us to define factors related to ontogenetic variation in leaf-level physiological traits and can be helpful in establishing periods appropriate for sampling birch leaves for diagnostic purposes such as assessment of plant and site productivity or effects of biotic or abiotic factors.
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  • 4
    ISSN: 1432-1939
    Keywords: Photosynthesis ; Respiration ; Pinus sylvestris ; Pinus nigra ; Betula pubescens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Light-saturated net photosynthesis (Asat), dark respiration (RD), and foliar nutrient content of eight European Scots pine (Pinus sylvestris L.) provenances were measured at experimental sites in western Poland. Two-year-old seedlings were planted in 1984 at two sites with similar soils in areas of contrasting air pollution. One site was near a point source of SO2 and other pollutants, and another 12 km to the southeast in an area free of acute air pollution was treated as a control. The eight provenances were from a large north-tosouth latitudinal range (60 to 43° N). At the heavily polluted site Scots pine trees exhibited lower growth rates and crown dieback and deformation. Soil pH, Ca and Mg were at least 10 times lower, and Al 10 times higher at the polluted than the control site. In 1991, concentrations of Al, P, Ca, S, Mn, Fe, and Zn in oneyear old Scots pine foliage were higher and Mg lower at the polluted than control site. At both sites foliar Mg levels were within the range considered deficient (≤0.6 mg g-1), and at the polluted site, Al concentrations were very high (670 to 880 μg g-1). In all provenances, RD of one-year-old needles was higher (by 22% on average) and Asat was lower (by 37% on average) at the polluted than the control site. The ratio of Asat: RD was half as great in all provenances at the polluted (4 to 6) than control site (8 to 11). Provenances of southern origin had greater increases in RD and water-use efficiency at the polluted site than other provenances. Within the polluted site alone, or across both sites, Asat in Scots pine was negatively correlated to the Al: Ca ratio (p〈0.001, r=−0.93). Across sites RD increased with needle N and Al (multiple regression, p〈0.001). The data suggest that at the polluted site there is excessive soil Al and deficient Mg availability, low needle Mg and high Al concentrations and high Al: Ca ratios, and that these have resulted in reduced photosynthetic capacity and increased respiration.
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