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  • relative growth rate  (3)
  • water stress  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Root and leaf attributes accounting for the performance of fast- and slow-growing grasses at different nutrient supply (1995)
    Springer
    Plant and soil 170 (1995), S. 251-265 
    Details
    ISSN: 1573-5036
    Keywords: dry matter content ; leaf area ratio ; relative growth rate ; root diameter ; root length ratio ; specific root length
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Despite their difference in potential growth rate, the slow-growing Brachypodium pinnatum and the fast-growing Dactylis glomerata co-occur in many nutrient-poor calcareous grasslands. They are known to respond differently to increasing levels of N and P. An experiment was designed to measure which characteristics are affected by nutrient supply and contribute to the ecological performance of these species. Nutrient acquisition and root and shoot traits of these grasses were studied in a garden experiment with nine nutrient treatments in a factorial design of 3 N and 3 P levels each. D. glomerata was superior to B. pinnatum in nutrient acquisition and growth in all treatments. B. pinnatum was especially poor in P acquisition. Both species responded to increasing N supply and to a lesser extent to increasing P supply by decreasing their root length and increasing their leaf area per total plant weight. D. glomerata showed a higher plasticity. In most treatments, the root length ratio (RLR) and the leaf area ratio (LAR) were higher for D. glomerata. A factorization of these parameters into components expressing biomass allocation, form (root fineness or leaf thickness) and density (dry matter content) shows that the low density of the biomass of D. glomerata was the main cause for the higher RLR and LAR. The biomass allocation to the roots showed a considerable plasticity but did not differ between the species. B. pinnatum had the highest leaf weight ratio. Root fineness was highly plastic in D. glomerata, the difference with B. pinnatum being mainly due to the thick roots of D. glomerata at high nutrient supply. The leaf area/leaf fresh weight ratio did not show any plasticity and was slightly higher for B. pinnatum. It is concluded, that the low density of the biomass of D. glomerata is the pivotal trait responsible for its faster growth at all nutrient levels. It enables simultaneously a good nutrient acquisition capacity by the roots as well as a superior carbon acquisition by the leaves. The high biomass density of B. pinnatum will then result in a lower nutrient requirement due to a slower turnover, which in the long term is advantageous under nutrient-poor conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010478
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of soil drying on growth, biomass allocation and leaf gas exchange of two annual grass species (1996)
    Springer
    Plant and soil 185 (1996), S. 137-149 
    Details
    ISSN: 1573-5036
    Keywords: C3 ; C4 ; relative growth rate ; Tragus racemosus ; Triticum aestivum ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Influence of short-term water stress on plant growth and leaf gas exchange was studied simultaneously in a growth chamber experiment using two annual grass species differing in photosynthetic pathway type, plant architecture and phenology:Triticum aestivum L. cv. Katya-A-1 (C3, a drought resistant wheat cultivar of erect growth) andTragus racemosus (L.) All. (C4, a prostrate weed of warm semiarid areas). At the leaf level, gas exchange rates declined with decreasing soil water potential for both species in such a way that instantaneous photosynthetic water use efficiency (PWUE, mmol CO2 assimilated per mol H2O transpired) increased. At adequate water supply, the C4 grass showed much lower stomatal conductance and higher PWUE than the C3 species, but this difference disappeared at severe water stress when leaf gas exchange rates were similarly reduced for both species. However, by using soil water more sparingly, the C4 species was able to assimilate under non-stressful conditions for a longer time than the C3 wheat did. At the whole-plant level, decreasing water availability substantially reduced the relative growth rate (RGR) ofT. aestivum, while biomass partitioning changed in favour of root growth, so that the plant could exploit the limiting water resource more efficiently. The change in partitioning preceded the overall reduction of RGR and it was associated with increased biomass allocation to roots and less to leaves, as well as with a decrease in specific leaf area. Water saving byT. racemosus sufficiently postponed water stress effects on plant growth occurring only as a moderate reduction in leaf area enlargement. For unstressed vegetative plants, relative growth rate of the C4 T. racemosus was only slightly higher than that of the C3 T. aestivum, though it was achieved at a much lower water cost. The lack of difference in RGR was probably due to growth conditions being relatively suboptimal for the C4 plant and also to a relatively large investment in stem tissues by the C4 T. racemosus. Only 10% of the plant biomass was allocated to roots in the C4 species while this was more than 30% for the C3 wheat cultivar. These results emphasize the importance of water saving and high WUE of C4 plants in maintaining growth under moderate water stress in comparison with C3 species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257570
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Polyamine concentrations in four Poa species, differing in their maximum relative growth rate, grown with free access to nitrate and at limiting nitrate supply (1998)
    Springer
    Plant growth regulation 24 (1998), S. 77-89 
    Details
    ISSN: 1573-5087
    Keywords: Poa species ; polyamines ; putrescine ; relative growth rate ; spermidine ; spermine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Polyamines are thought to play a role in the control of inherent or environmentally-induced growth rates of plants. To test this contention, we grew plants of four grass species, the inherently fast-growing Poa annua L. and Poa trivialis L. and the inherently slow-growing Poa compressa L. and Poa pratensis (L.) Schreb., at three levels of nitrate supply. Firstly, plants were compared when grown with free access to nitrate, allowing the plants to grow at their maximum relative growth rate (RGRmax). Secondly, we compared the plants when grown with relative nitrate addition rates of 100 and 50 mmol N (mol N)−1 day−1 (RAR100 and RAR50, respectively). The freely-occurring polyamines, spermine, spermidine and putrescine, were separated from their conjugates; the latter were further subdivided into a TCA-soluble and a TCA-insoluble fraction. Each of the three fractions responded differently to the nitrate supply. Under nitrogen limitation, the total concentration of polyamines (free and bound ones together) decreased in both leaves and roots of all Poa species, whereas that in the stem remained more or less the same. These effects were to a large extent determined by the free polyamines. For the conjugates there was more differentiation, both between plant organ and among polyamine structures. A positive correlation between the RGR, LAR (leaf area per plant mass), SLA (leaf area per leaf mass), LMR (leaf mass per plant mass) and SMR (stem mass per plant mass) with the polyamine concentration was found. The RMR (root mass per plant mass) showed a negative one. No significant differences were found between the inherently fast- and slow-growing grass species. The (putrescine)/(spermine + spermidine) ratio in the leaves increased with decreasing nitrate supply, which is associated with a decrease in leaf expansion, accounting for a decrease in LAR and SLA. For the roots, this ratio tended to decrease with decreasing nitrate supply, whereas for the stems the results were somewhat more variable. We found no evidence for a crucial role of polyamines in the determination of inherent variation of growth in spite of a positive correlation of especially the free polyamines with growth parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005946330580
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  • 4
    Electronic Resource
    Electronic Resource
    Carbon use in root respiration as affected by elevated atmospheric O2 (1995)
    Springer
    Plant and soil 187 (1995), S. 251-263 
    Details
    ISSN: 1573-5036
    Keywords: carbon budget ; CO2 ; global change ; nutrient status ; root respiration ; root weight ratio ; temperature ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The use of fossil fuel is predicted to cause an increase of the atmospheric CO2 concentration, which will affect the global pattern of temperature and precipitation. It is therefore essential to incorporate effects of temperature and water supply on the carbon requirement for root respiration of plants to predict effects of elevated [CO2] on the carbon budget of natural and managed systems. There is insufficient information to support the contentention that an increase in the concentration of CO2 in the atmosphere will enhance the CO2 concentration in the soil to an extent that is likely to affect root respiration. Moreover, there is no convincing evidence for a direct effect of elevated atmospheric [CO2] on the rate of root respiration per unit root mass or the fraction of carbon required for root respiration. However, there are likely to be indirect effects of elevated [CO2] on the carbon requirement of plants in natural systems. Firstly, it is very likely that the carbon requirement of root respiration relative to that fixed in photosynthesis will increase when elevated [CO2] induces a decrease in nutrient status of the plants. Although earlier papers have emphasized that elevated [CO2] favours investment of biomass in roots relative to that in leaves, these are in fact indirect effects. The increase in root weight ratio is due to the more rapid depletion of nutrients in the root environment as a consequence of enhanced growth. This will decrease the specific rate of root respiration, but increase the carbon requirement as a fraction of the carbon fixed in photosynthesis. It is likely that these effects will be minor in systems where the nutrient supply is very high, e.g. in many managed arable systems, and increase with decreasing soil fertility, i.e. in many natural systems. Secondly, a decrease in rainfall in some parts of the world may cause a shortage in water supply which favours the carbon partitioning to roots. Water stress is likely to reduce rates of root respiration per unit root mass, but enhance the fraction of total assimilates required for root respiration, due to greater allocation of biomass to roots. Increased temperatures are unlikely to affect the specific rate of root respiration in all species. Broadly generalized, the effect of temperature on biomass allocation is that the relative investment of biomass in roots is lowest at a certain optimum temperature and increases at both higher and lower temperatures. The root respiration of some species acclimates to growth temperature, so that the effect of global temperature rise is entirely accounted for by the effect of temperature on biomass allocation. The specific rate of root respiration of other species will increase with global warming. In response to global warming the carbon requirement of roots is likely to decrease in temperate regions, when temperatures are suboptimal for the roots' capacity to acquire water. Here global warming will induce a smaller biomass allocation to the roots. Conversely, the carbon requirements are more likely to increase in mediterranean environments, where temperatures are often supraoptimal and a rise in temperature will induce greater allocation of biomass to the roots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00017091
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    Paper (German National Licenses)
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