Comparison of growth characteristics and tolerance to serpentine soil of three ectomycorrhizal spruce seedlings in northern Japan

Picea glehnii is distributed widely on serpentine soils in northern Japan. Serpentine soil is characterised by the presence of heavy metals (Ni, Cr) and excessive Mg; these elements often suppress plant growth. We have examined the tolerance to serpentine soil and its effects on growth of P. glehnii, P. jezoensis (distributed in the same region) and P. abies (planted for timber production).The dry mass of each organ was not reduced in P. glehnii planted in serpentine soil contained nursery (serpentine nursery). In contrast, growth of P. jezoensis and P. abies was suppressed. Concentrations of Ni and Mg in needles and roots of P. glehnii planted in serpentine nursery were the lowest of the three species. Moreover, the photosynthetic rate of P. glehnii planted in the serpentine nursery was not reduced. P. glehnii has high capability to maintain low concentration of Ni, and ectomycorrhizal symbiosis may have a positive effect to excluding Ni. As a result, P. glehnii has a high tolerance against Ni toxicity, and its photosynthetic capacity is not suppressed by accumulation of Ni.     

Agrobacterium tumefaciens-mediated transformation of hybrid larch (Larix kaempferi T L. decidua) and transgenic plant regenerationn

A transformation procedure was developed for hybrid larch embryogenic tissue using Agrobacterium tumefaciens. The cocultivation procedure yielded one to two transformation events per 100 cocultivated masses. The addition of 100 μm coniferyl alcohol increased the yield. This improved procedure was successfully applied to three other genotypes. After 3 months on selective medium, the transgenic tissue remained embryogenic, which allowed production of transgenic plants in the greenhouse. Stable integration of the transgene was confirmed by PCR and Southern hybridisation on transformed tissues and acclimatised plants. Received: 4 July 1996 / Revision received: 25 November 1996 / Accepted: 10 December 1996     

Differences in growth characteristics and dynamics of elements absorbed in seedlings of three spruce species raised on serpentine soil in northern Japan

BACKGROUND AND AIMS: Serpentine soils are characterized by the presence of heavy metals (Ni and Cr) and excess Mg; these elements often suppress plant growth. Picea glehnii is nevertheless distributed widely on serpentine soils in northern Japan. Growth characteristics were compared among P. glehnii, Picea jezoensis (distributed in the same region) and Picea abies (planted for timber production), and concentrations of elements in various tissues over time and the amount of ectomycorrhizal infection in short roots were evaluated. METHODS: Seedlings of three spruce species were planted in two types of experimental plots, comprising serpentine soil and brown forest (non-serpentine) soil, and these seedlings were grown for 3 years. Growth, ectomycorrhizal infection of short roots, and elemental composition of tissues were examined. KEY RESULTS: The total dry mass of P. glehnii planted on serpentine soil was almost the same as on brown forest soil, and a large number of needles survived to reach later age classes. By contrast, growth of P. jezoensis and P. abies in serpentine soil was significantly less than in brown forest soil, and needle shedding was accelerated. Moreover, roots of seedlings of P. glehnii on serpentine soil were highly infected with ectomycorrhiza, and the concentration of Ni in needles and roots of P. glehnii was the lowest of the three species. CONCLUSIONS: Picea glehnii has a high ability to maintain a low concentration of Ni, and the ectomycorrhizal infection may have the positive effect of excluding Ni. As a result, P. glehnii is more tolerant than the other spruce species to serpentine soil conditions.     

Growth characteristics of Sakhalin spruce (Picea glehnii) planted on the northern Japanese hillsides exposed to strong winds

Sakhalin spruce (Picea glehnii), a native species typically found in northern Japan, has been used in reforestation on hillsides exposed to strong winds. In the reforestation areas, there are south-facing (S-slope) and northwest-facing slopes (NW-slope). Climatic conditions are contrasting between the two slopes, with shallower snow cover on the S-slopes. We compared growth responses of the spruce to micro-environment between the S- and NW-slopes through soil nutrients, needle longevity, water status, photosynthesis, and nutrients in the needles. These parameters were measured in needles exposed above the snow in winter and in lower needles protected by snow cover. High-position needles suffered from drought stress, especially in winter, and needles were shed early in the year on both slopes. Low-position needles did not suffer from drought stress, and maintained a high photosynthetic rate on both slopes. However, needle longevity was reduced on the S-slope, and concentrations of nitrogen, phosphorus, and potassium in the needles decreased with needle age. Soil nutrient concentrations were low on the S-slope, which suggests that the needles on the S-slope may remobilize nutrients from aged needles to younger needles prior to shedding. This characteristic is probably an adaptation in Sakhalin spruce to poor soil conditions.     

Natural regeneration patterns of the introduced larch, Larix kaempferi (Pinaceae), on the volcano Mount Koma, northern Japan

The 1929 eruption of Mount Koma (1140 m in altitude) completely deforested the vegetation on the summit area of the volcano. An alien species of larch, Larix kaempferi (=L. leptolepis) was planted on the lower slopes of the volcano between 1953 and 1963, but since then has become abundant on the summit. To determine the regeneration patterns of the larch, we measured stem densities on aerial photographs taken in 1963, 1973 and 1994, and in the field during 1996. Larix kaempferi stems with crown diameters > 2 m were mapped on aerial photographs divided into 1083 100 m×100 m grids. Stem densities on the summit increased from 0.8/ha in 1963, to 14.1/ha in 1994. Willows and birches also established there but did not grow as large as the larch. All these species are wind dispersed, and larch densities were higher in areas closer to the plantations, suggesting that wind intensity and direction determined seed migration. Four environmental factors—slope gradient, direction, elevation, and distance from the plantations in each grid—were correlated with larch stem densities. Multiple regression showed that establishment patterns of L. kaempferi in the early stages were mainly related to distance from seed source (the plantations). Later, geographical disturbances and/or physiological stresses became more important. Density effects on tree invasion have been weak until now. We concluded that revegetation primarily depends on the chance of seed immigration, and that the larches may be an earlier successional species than any other native tree species.     

Seasonal changes in the photosynthetic capacity of cones on a larch (Larix kaempferi) canopy

The seasonal changes of photosynthesis of cones of Japanese larch (Larix kaempferi Carr.) trees showed that gross photosynthetic rate of young cones (P _G) was 2–3 μmol m⁻² s⁻¹ at surface area unit and P _G/R _D (dark respiration of cones) peaked about 0.7 in the same period, indicating that 70 % of respiratory CO₂ was re-fixed. With maturation, P _G and P _G/R _D sharply decreased. Chlorophyll content in cones was 3–20 % of that in leaves, which made it a limiting factor for photosynthesis and its content was closely correlated with photosynthetic capacity. Although sunken and linearly arranged stomatal organs were found on the scale of young cones, differently from the significant regulation of leaf photosynthesis, these stomata tended to be non-functional since CO₂ is not limiting factor for cone photosynthesis. Thus photosynthesis of larch cones is an additional contribution to their development.     

Provenance tests for survival and growth of 50-year-old Japanese larch (Larix kaempferi) trees related to climatic conditions in central Japan

Survival and growth of Japanese larch (Larix kaempferi) from 25 provenances in the natural distributional range were examined at three test sites in central Japan. Climatic conditions of the sites and provenances indicated a contrast between northwest and southeast locations across the distributional range. Density, height, diameter, and crookedness of stems and width and length of branches were measured for 50-year-old trees, and per-area cross-sectional area and volume of stems were calculated. Variance components among the provenances were large in the stem area and volume (27–33 %) and the branch width (26 %); those among the sites were large in the stem height, diameter, and density (70–81 %); and those of interaction between sites and provenances were small (0–12 %) in all the variables. Principal component analyses showed that eastern provenances exhibited large size of stems and branches at most sites. Growth rate and maximum size at each site were estimated from fitting the stem volume at three ages (12, 31 or 32, and 50 years) to growth curves in logistic functions. Eastern provenances, where seasonal variation is least in temperature and most in precipitation, showed the highest performance of stem and branch growth. The findings from our long-term survey of the L. kaempferi provenance tests suggest climatic effects on survival and growth traits and potential provenances from which to select new breeding materials.     

The effect of nitrogen nutrition on growth and biomass partitioning of annual plants originating from habitats of different nitrogen availability

Summary The hypothesis was tested that faster growth of nitrophilic plants at high nitrogen (N) nutrition is counterbalanced by faster growth of non-nitrophilic plants at low N-nutrition. Ten annual plant species were used which originated from habitats of different N-availability. The species' preference for N was quantified by the N-number of Ellenberg (1979), a relative measure of nitrophily. The plants were cultivated in a growth cabinet at five levels of ammonium-nitrate supply. At low N-supply, the relative growth rate (RGR) was independent of nitrophily. At high N-supply, RGR tended to be higher in nitrophilic than in non-nitrophilic species. However, the response of RGR to N-supply was strongly and positively correlated with the nitrophily of species. Increasing N-supply enhanced partitioning to leaf weight per total biomass (LWR) and increased plant leaf area per total biomass (LAR). Specific leaf weight (SLW) and LWR were both higher in non-nitrophilic than in nitrophilic species at all levels of N-nutrition. NAR (growth per leaf area or net assimilation rate) increased with nitrophily only under conditions of high N-supply. RGR correlated positively with LAR, irrespective of N-nutrition. Under conditions of high N-supply RGR correlated with SLW negatively and with NAR positively.     

Identification of larch species (Larix decidua, Larix kaempferi and Larix X eurolepis) and estimation of hybrid fraction in seed lots by RAPD fingerprints

Species-specific RAPD markers were used to identify the different larch species (Larix decidua and Larix kaempferi) and their interspecific hybrid (Larix X eurolepis). Although morphological differences between pure species and the hybrids exist, differentiation is not always possible, especially at an early stage (seed or plantlet). Eleven RAPD markers differentiated the two larch species, and 4 species-specific markers were sufficient to estimate the F₁ hybrid fraction in a seed lot. The species-specific markers were tested on individual trees of European and Japanese larches of diverse geographic origins and on several seed lots of different origins (F₁, F₂ hybrids and pure species). The 4 specific markers found for the European larch and the Japanese larch were monomorphic and present in all provenances and in all F₁ hybrid trees tested. Polymorphic SCAR fragments were obtained for 3 of the 11 fragments originally selected for the RAPD screening phase. For 2 of them, the sequence had some homology with the mitochondrial genome of other organisms and is thus mitochondrial. The two mitochondrial fragments and the OPF-13₁₀₀₀ fragment exhibited one polymorphic band, thereby maintaining its species-specific identity: OPF-13₁₀₀₀ is specific to the European larch. The 4 RAPD primers selected in this study offer a reliable, quick and cheap tool for the identification of different larch species (Larix decidua and Larix kaempferi) and their interspecific hybrid (Larix X eurolepis). Received: 28 February 1999 / Accepted: 29 April 1999     

模拟酸雨及其酸化土壤对小麦幼苗体内可溶性糖和含氮量的影响

以小麦为试材,采用盆栽方法研究了模拟酸雨及其酸化土壤对小麦幼苗体内可溶性糖和含N量的影响.结果表明,pH值为5.6、4.5、3.5、3.0和2.5的系列模拟酸雨引起了土壤酸化和盐基流失.当模拟酸雨的pH值由5.6下降到2.5时,被淋溶土壤的pH值由.0下降到3.41,土壤中交换性盐基总量从56.5下降到41.1mmol·kg^-1.将小麦幼苗栽培在该系列酸化土壤上,并分别用5种不同pH值的模拟酸雨喷淋地上器官,导致小麦幼苗体内的可溶性糖含量、含N量迅速下降,某些生理活动降低.其中,模拟酸雨喷淋对小麦幼苗茎叶可溶性糖含量、含N量、叶绿素含量以及光合速率的影响大于酸化土壤对其产生的影响.而酸化土壤对小麦幼苗根系中可溶性糖含量、含N量、硝酸还原酶(NR)和谷氨酸合成酶(GOGAT)活性的影响大于模拟酸雨喷淋的影响.pH≤3.0的高强度酸雨以及由其产生的酸化土壤(T₄、T₅土壤)对小麦幼苗的碳素代谢和氮素代谢具有明显的抑制作用.     

Growth,biomass allocation and plant nitrogen concentration in Chilean temperate rainforest tree seedlings: effects of nutrient availability

Seedlings of nine southern Chilean trees were grown at three nutrient supply rates, to examine the roles of growth rate, biomass distribution and nutrient use traits in determining species natural distributions on resource gradients. Relative growth rate (RGR) showed no overall relationship with species site requirements, although RGR of fertile-site species tended to be more responsive to nutrient supply. In the low-nutrient treatment, infertility-tolerant Fitzroya cupressoides showed a higher RGR rank than a fertility-demanding species (Laurelia philippiana) which outgrew it substantially at the highest supply rate. This reversal of RGR ranks was associated with divergent nutrient use responses: at high nutrient supply both spp. had similar plant nitrogen concentrations (PNC), whereas at the low supply rate Fitzroya’s production of biomass per unit of assimilated N was twice that of Laurelia’s. However, this pattern does not appear to serve as a general explanation of the respective distributions of the study species, as RGR ranks of most species were unaltered by nutrient supply. At low nutrient availability, no clear differences in shoot:root ratio (SRR) were apparent between poor-site and fertile-site species. However, at high nutrient availability, SRR was markedly higher in the latter, resulting from differences in biomass allocation to stems (not leaves). Leaf area ratios (LAR) were higher in fertile-site species than in those tolerant of low fertility, because of differences in specific leaf area rather than leaf weight ratio. Very high LAR at high nutrient supply was characteristic of most shade-tolerant angiosperms, but not of shade-tolerant conifers. Although PNC showed no overall differences between poor- and fertile-site species, sensitivity of PNC to external supply rate was greatest in two infertility-tolerant conifers. In contrast, the angiosperm Weinmannia trichosperma, although tolerant of low fertility, responded to increased nutrient supply with greatly increased RGR and little change in PNC. Results show little trait convergence between conifers and angiosperms in adaptation both to shade and to infertile soils; i.e. fitness of different taxa in a given environment may hinge on different trait combinations. Received: 12 September 1995 /Accepted: 14 June 1996     

Relative growth rate in relation to physiological and morphological traits for northern hardwood tree seedlings: species,light environment and ontogenetic considerations

The influence of ontogeny, light environment and species on relationships of relative growth rate (RGR) to physiological and morphological traits were examined for first-year northern hardwood tree seedlings. Three Betulaceae species (Betula papyrifera, Betula alleghaniensis and Ostrya virginiana) were grown in high and low light and Quercus rubra and Acer saccharum were grown only in high light. Plant traits were determined at four ages: 41, 62, 83 and 104 days after germination. In high light (610 mol m^–2 s^–1 PPFD), across species and ages, RGR was positively related to the proportion of the plant in leaves (leaf weight ratio, LWR; leaf area ratio, LAR), in situ rates of average canopy net photosynthesis (A) per unit mass (A_mass) and per unit area (A_area), and rates of leaf, stem and root respiration. In low light (127 mol m^–2 s^–1 PPFD), RGR was not correlated with A_mass and A_area whereas RGR was positively correlated with LAR, LWR, and rates of root and stem respiration. RGR was negatively correlated with leaf mass per area in both high and low light. Across light levels, relationships of CO₂ exchange and morphological characteristics with RGR were generally weaker than within light environments. Moreover, relationships were weaker for plant parameters containing a leaf area component (leaf mass per area, LAR and A_area), than those that were solely mass-based (respiration rates, LWR and A_mass). Across light environments, parameters incorporating the proportion of the plant in leaves and rates of photosynthesis explained a greater amount of variation in RGR (e.g. LWR^*A_mass, R²=0.64) than did any single parameter related to whole-plant carbon gain. RGR generally declined with age and mass, which were used as scalars of ontogeny. LWR (and LAR) also declined for seven of the eight species-light treatments and A declined in four of the five species in high light. Decreasing LWR and A with ontogeny may have been partially responsible for decreasing RGR. Declines in RGR were not due to increased respiration resulting from an increase in the proportion of solely respiring tissue (roots and stems). In general, although LWR declined with ontogeny, specific rates of leaf, stem, and root respiration also decreased. The net result was that whole-plant respiration rates per unit leaf mass decreased for all eight treatments. Identifying the major determinants of variation in growth (e.g. LWR^*A_mass) across light environments, species and ontogeny contributes to the establishment of a framework for exploring limits to productivity and the nature of ecological success as measured by growth. The generality of these relationships both across the sources of variation we explored here and across other sources of variation in RGR needs further study.     

Growth,biomass distribution and CO2 exchange of northern hardwood seedlings in high and low light: relationships with successional status and shade tolerance

The physiology, morphology and growth of first-year Betula papyrifera Marsh., Betula alleghaniensis Britton, Ostrya virginiana (Mill.) K. Koch, Acer saccharum Marsh., and Quercus rubra L. seedlings, which differ widely in reported successional affinity and shade tolerance, were compared in a controlled high-resource environment. Relative to late-successional, shade-tolerant Acer and Ostrya species, early-successional, shade-intolerant Betula species had high relative growth rates (RGR) and high rates of photosynthesis, nitrogen uptake and respiration when grown in high light. Fire-adapted Quercus rubra had intermediate photosynthetic rates, but had the lowest RGR and leaf area ratio and the highest root weight ratio of any species. Interspecific variation in RGR in high light was positively correlated with allocation to leaves and rates of photosynthesis and respiration, and negatively related to seed mass and leaf mass per unit area. Despite higher respiration rates, early-successional Betula papyrifera lost a lower percentage of daily photosynthetic CO₂ gain to respiration than other species in high light. A subset comprised of the three Betulaceae family members was also grown in low light. As in high light, low-light grown Betula species had higher growth rates than tolerant Ostrya virainiana. The rapid growth habit of sarly-successional species in low light was associated with a higher proportion of biomass distributed to leaves, lower leaf mass per unit area, a lower proportion of biomass in roots, and a greater height per unit stem mass. Variation in these traits is discussed in terms of reported species ecologies in a resource availability context.     

Negative effects of hydroxyl radical-generating mists (simulated dew water) on the photosynthesis and growth of Japanese apricot seedlings (Prunus mume)

The hydroxyl (OH) radical, which is generated in polluted dew water on leaf surfaces of the Japanese apricot (Prunus mume), is known to be a potent oxidant. In order to investigate the effects of the OH radical formed in polluted dew water on the photosynthesis and growth of 3-year-old seedlings of P. mume, OH radical-generating solutions simulating polluted dew water were sprayed in the early morning as a mist throughout a growing season onto the leaf surfaces of seedlings growing in experimental greenhouses. Four OH radical-generating solutions (0, 6, 18 and 54 M H₂O₂ with Fe(III) and an oxalate ion) were used in the mist treatment. Five months after the beginning of treatment, the leaves exposed to the mist containing 54 M H₂O₂ showed a significantly smaller maximum CO₂ assimilation rate (A_max) and stomatal conductance (g_s) as compared to the leaves exposed to the mist containing 0 M H₂O₂. Exposure of P. mume seedlings to the OH radical-generating mist had caused a reduction in the dry weight and relative growth rate (RGR) of the above-ground parts (stem + branch) at the end of the growing season. A significant positive correlation was shown between RGR and A_max. Thus, the effects of oxidants generated in polluted dew water on leaf surfaces can be considered to be a cause of the decrease in leaf photosynthesis and growth of P. mume.     

Changes in soil organic carbon,nitrogen, pH and bulk density with the development of larch (Larix gmelinii) plantations in China

Under the government of China's environmental program known as Returning Farmland To Forests (RFTF), about 28 million hectares of farmland have been converted to tree plantation. This has led to a large accumulation of biomass carbon, but less is known about underground carbon‐related processes. One permanent plot (25 years of observation) and four chronosequence plot series comprising 159 plots of larch (Larix gmelinii) plantations in northeastern China were studied. Both methods found significant soil organic carbon (SOC) accumulation (96.4 g C m^?2 yr^?1) and bulk density decrease (5.7 mg cm^?3 yr^?1) in the surface soil layer (0–20 cm), but no consistent changes in deeper layers, indicating that larch planting under the RFTF program can increase SOC storage and improve the physical properties of surface soil. Nitrogen depletion (4.1–4.3 g m^?2 yr^?1), soil acidification (0.007–0.022 pH units yr^?1) and carbon/nitrogen (C/N) ratio increase (0.16–0.46 per year) were observed in lessive soil, whereas no significant changes were found in typical dark‐brown forest soil. This SOC accumulation rate (96.4 g m^?2 yr^?1) can take 39% of the total carbon sink capacity [net ecosystem exchange (NEE)] of larch forests in this region and the total soil carbon sequestration could be 87 Tg carbon within 20 years of plantation by approximating all larch plantations in northeastern China (4.5 Mha), showing the importance of soil carbon accumulation in the ecosystem carbon balance. By comparison with the rates of these processes in agricultural use, the RFTF program of reversing land use for agriculture will rehabilitate SOC, soil fertility and bulk density slowly (< 69% of the depletion rate in agricultural use), so that a much longer duration is needed to rehabilitate the underground function of soil via the RFTF program. Global forest plantations on abandoned farmland or function to protecting farmland are of steady growth and our findings may be important for understanding their underground carbon processes.     

The effects of enhanced ultraviolet-B and nitrogen supply on growth,photosynthesis and nutrient status of <Emphasis Type="Italic">Abies faxoniana</Emphasis> seedlings

Abies faxoniana is a key species in reforestation processes in the southeast of the Qinghai-Tibetan Plateau of China. The changes in growth, photosynthesis and nutrient status of A. faxoniana seedlings exposed to enhanced ultraviolet-B (UV-B), nitrogen supply and their combination were investigated. The experimental design included two levels of UV-B treatments (ambient UV-B, 11.02 KJ m⁻² day⁻¹; enhanced UV-B, 14.33 KJ m⁻² day⁻¹) and two nitrogen levels (0; 20 g N m⁻²). The results indicated that: (1) enhanced UV-B significantly caused a marked decline in growth parameters, net photosynthetic rate (Pn), photosynthetic pigments and F _v/F _m, (2) supplemental nitrogen supply increased the accumulation of total biomass, Pn, photosynthetic pigments and F _v/F _m under ambient UV-B, whereas supplemental nitrogen supply reduced Pn, and not affect biomass under enhanced UV-B, (3) enhanced UV-B or nitrogen supply changed the concentration of nutrient elements of various organs.     

Soil carbon storage, litterfall and CO2 efflux in fertilized and unfertilized larch (Larix leptolepis) plantations

This study evaluated the effects of forest fertilization on the forest carbon (C) dynamics in a 36-year-old larch (Larix leptolepis) plantation in Korea. Above- and below-ground C storage, litterfall, root decomposition and soil CO₂ efflux rates after fertilization were measured for 2 years. Fertilizers were applied to the forest floor at rates of 112 kg N ha⁻¹ year⁻¹, 75 kg P ha⁻¹ year⁻¹ and 37 kg K ha⁻¹ year⁻¹ for 2 years (May 2002, 2003). There was no significant difference in the above-ground C storage between fertilized (41.20 Mg C ha⁻¹) and unfertilized (42.25 Mg C ha⁻¹) plots, and the C increment was similar between the fertilized (1.65 Mg C ha⁻¹ year⁻¹) and unfertilized (1.52 Mg C ha⁻¹ year⁻¹) plots. There was no significant difference in the soil C storage between the fertilized and unfertilized plots at each soil depth (0–15, 15–30 and 30–50 cm). The organic C inputs due to litterfall ranged from 1.57 Mg C ha⁻¹ year⁻¹ for fertilized to 1.68 Mg C ha⁻¹ year⁻¹ for unfertilized plots. There was no significant difference in the needle litter decomposition rates between the fertilized and unfertilized plots, while the decomposition of roots with 1–2 mm diameters increased significantly with the fertilization relative to the unfertilized plots. The mean annual soil CO₂ efflux rates for the 2 years were similar between the fertilized (0.38 g CO₂ m⁻² h⁻¹) and unfertilized (0.40 g CO₂ m⁻² h⁻¹) plots, which corresponded with the similar fluctuation in the organic carbon (litterfall, needle and root decomposition) and soil environmental parameters (soil temperature and soil water content). These results indicate that little effect on the C dynamics of the larch plantation could be attributed to the 2-year short-term fertilization trials and/or the soil fertility in the mature coniferous plantation used in this study.     

Growth and nutrient dynamics of beech (Fagus sylvatica L.) seedlings in acid soils

The relative uptake rates of N, P, K, S, Ca, Mg, Fe, Mn, Zn, Cu, and Al were estimated in beech seedlings pot cultured in the field in six acid soils (treatments). The relative uptake rates were compared with the relative growth rates. The relative uptake rates of N, K and Ca agreed well with the growth rates of the seedlings irrespective of widely differing soil conditions (acid sand-clayey till, pH 4–6). The relative uptake rates of P, Fe, and Al differed from that predicted by the growth rate. The uptake rates of Fe and Al were highest at the lowest growth rates, and the P uptake rate was lower than the growth rate in these treatments. Thus the P availability probably limited growth in an eluvial (E) horizon of a podzol, and possibly in the illuvial (B) horizon of a podzol and in an acid clayey till (Dystric Cambisol). Low P uptake was associated with a tendency towards higher relative root growth rates. In terms of the concept of steady state nutrition the high relative root growth rate in some treatments may be interpreted as an acclimation to low P supply. The P limitation seemed to be related to interactions among Fe, Al and organic compounds of the soil solution.FAX no: +4646104423