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  • N2 fixation  (4)
  • Planaria  (3)
  • Springer  (7)
  • Cell Press
  • 1
    Electronic Resource
    Electronic Resource
    Phosphorus requirements and nitrogen accumulation by N2-fixing and non-N2-fixing leguminous trees growing in low P soils (1995)
    Springer
    Biology and fertility of soils 20 (1995), S. 205-211 
    Details
    ISSN: 1432-0789
    Keywords: Gliricidia sepium ; Isotope dilution ; Low P soil ; P use efficiency ; 15N uptake ; N2 fixation ; Senna siamea ; Senna spectabilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The variation in P uptake and use efficiency and N accumulation by Gliricidia sepium (N2-fixing tree), Senna siamea and S. spectabilis (leguminous non-N2-fixing trees) were examined in the field at Fashola (savanna zone), southwestern Nigeria, using four P rates, 0, 20, 40 and 80 kg P ha-1. Growth of G. sepium and S. spectabilis responded to P application at 24 weeks after planting (WAP) and average yield increases of 58% and 145% were observed by the application of 40 kg P ha-1 for the two species, respectively. Such a P response was not found in S. siamea at 24 WAP and for any of the species at 48 WAP. G. sepium accumulated more P (on average 162%) than S. siamea and S. spectabilis at 24 WAP and had greater root length and a higher percentage of mycorrhizal infection. However, at 48 WAP S. siamea had 2.5 times more P than G. sepium. Differences in the physiological P use efficiency (PPUE) between G. sepium and the non-N2-fixing trees were significant at the 0 P level, being higher for S. siamea (average, 0.61 g shoot mg-1 P) than for G. sepium (0.27 g shoot mg-1 P). G. sepium had a consistently lower atom % 15N than S. spectabilis, while that of S. siamea for most of the time did not differ from that of G. sepium. The reference plant affected N2 fixation extimates, with negative values and a higher variability (CV 60%) associated with S. siamea than with S. spectabilis (CV〈20%). Consequently, S. spectabilis was selected as a better reference plant for measuring N2 fixation in G. sepium. G. sepium fixed on average 35% and 54% of its N at 24 and 48 WAP, respectively. Except at the lowest P rate, percentage and amount of N fixed were not generally enhanced by P application.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336559
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of successive cuttings on uptake and partitioning of 15N among plant parts of Leucaena leucocephala (1990)
    Springer
    Biology and fertility of soils 9 (1990), S. 37-42 
    Details
    ISSN: 1432-0789
    Keywords: Agroforestry ; Cutting ; Leucaena leucocephala ; N distribution ; N2 fixation ; N uptake ; 15N isotope ; Rhizobium spp.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary We studied the effect of three successive cuttings on N uptake and fixation and N distribution in Leucaena leucocephala. Two isolines, uninoculated or inoculated with three different Rhizobium strains, were grown for 36 weeks and cut every 12 weeks. The soil was labelled with 50 ppm KNO3 enriched with 10 atom % 15N excess soon after the first cutting. Except for the atom % 15N excess in branches of K28 at the second cutting, both the L. leucocephala isolines showed similar patterns of total N, fixed N2, and N from fertilizer distribution in different parts of the plant at each cutting. The Rhizobium strain did not influence the partitioning of 15N among the different plant parts. Significant differences in 15N enrichment occurred in different parts. Live nodules of both isolines showed the lowest atom % 15N excess values (0.087), followed by leaves (0.492), branches (0.552), stems (0.591), and roots (0.857). The roots contained about 60% of the total plant N and about 70% of the total N derived from fertilizer over the successive cuttings. The total N2 fixed in the roots was about 60% of that fixed in the whole plant, while the shoots contained only 20% of the fixed N2. We conclude that N reserves in roots and nodules constitute another N source that must be taken into account when estimating fixed N2 or the N balance after pruning or cutting plants. 15N enrichment declined up to about fivefold in the reference and the N2-fixing plants over 24 weeks following the 15N application. The proportion and the amounts of N derived from fertilizer decreased, while the amount derived from N2 fixation increased with time although its proportion remained constant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335859
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  • 3
    Electronic Resource
    Electronic Resource
    Cell autolysis and deletion in the planarian polycelis tenuis Iijima (1974)
    Springer
    Cell & tissue research 154 (1974), S. 265-274 
    Details
    ISSN: 1432-0878
    Keywords: Cell autolysis ; Deletion ; Planaria ; Acid phosphatase ; Fine structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Selective cell autolysis and deletion is described in the normal adult planarian. This appears to be a common feature and the sequence of events leading from cytoplasmic vesiculation and peripheral lysis to complete cellular breakdown is described. — In lysing cells acid phosphatase activity can be demonstrated in the cytoplasm as well as in lysosome like vacuoles and occasionally in the Golgi apparatus. The role of cell autolysis and deletion in tissue regulation is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223168
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  • 4
    Electronic Resource
    Electronic Resource
    The effects of starvation on the planarian worm Polycelis tenuis iijima (1976)
    Springer
    Cell & tissue research 169 (1976), S. 193-209 
    Details
    ISSN: 1432-0878
    Keywords: Planaria ; Starvation ; Fine structure ; Biochemistry ; Cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Employing a combination of microscopical, biochemical and autoradiographic techniques, the primary effects of starvation on adult Polycelis tenuis have been studied. Over a five week period of starvation there is on average a 32% decrease in the size of the organism. This decrease is contributed to by a reduction in mitosis and an increase in cell shrinkage autolysis and death. During starvation (following a sharp rise in RNA synthesis) there is a distinct sequence of events; four peaks of acid phosphatase activity can be resolved. The first is associated with the immediate response of the gastrodermis to feeding; the second (after 6 to 7 days) with increased autophagy and dedifferentiation in the gland cells and with muscle lysis; the third peak (after 14 to 15 days) is contributed to largely by the lysis of cells in the gut and the fourth peak (after 25 to 26 days) is caused by an extensive lysis of the reproductive system. Fine structural changes involving increased intracellular vacuolation, autophagy, crinophagy, atrophy of muscle, increased intercellular space and loss of basement membrane matrix have been related to changes in enzyme pattern. Nerve cells appear unchanged throughout the first five weeks of starvation. Pigment and gland cells loose their characteristic granules, dedifferentiate and become morphologically similar to the undifferentiated neoblasts. Dedifferentiation and the mechanisms involved in the survival of starvation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214208
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  • 5
    Electronic Resource
    Electronic Resource
    The distribution of oxidizable mucosubstances and polysaccharides in the planarian Polycelis tenuis iijima (1975)
    Springer
    Cell & tissue research 161 (1975), S. 263-275 
    Details
    ISSN: 1432-0878
    Keywords: Oxidizable mucosubstances ; Fine structure ; Planaria ; X-ray microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A chromic acid oxidation-silver technique was used to localize polysaccharide material in Polycelis tenuis at the electron microscope level. In the epithelium, staining was observed within apical vacuoles and on the free surfaces of the cells. A similar staining was observed in relation to the glycocalyx of the pharyngeal epithelia and that of the flame cells. Silver was deposited in the basement membrane. In the parenchyma, the major components giving a positive reaction were the cyanophil and mucous gland cells. Particularly strong silver staining (confirmed by X-ray microanalysis) was observed in the granules and Golgi apparatus of the cyanophil cells. IDPase activity was also found in relation to the Golgi apparatus and its secretory products. The overall distribution of mucopolysaccharide material was confirmed with the PAS and Alcian blue techniques. The fine structural localization of the Alcian blue was also determined using electron microscopy and X-ray microanalysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220373
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  • 6
    Electronic Resource
    Electronic Resource
    Intra-specific variation in growth and P accumulation of Leucaena leucocephala and Gliricidia sepium as influenced by soil phosphate status (1991)
    Springer
    Plant and soil 133 (1991), S. 201-208 
    Details
    ISSN: 1573-5036
    Keywords: isolines ; nodulation ; N2 fixation ; P uptake ; P use efficiency ; provenances ; Rhizobium ; rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Twenty-three provenances of Gliricidia sepium and eleven isolines of Leucaena leucocephala were examined at a low and at high phosphate levels (20 and 80 mg P kg-1 soil) for growth, phosphate (P) uptake and use efficiency. Large differences in growth at the low P level, and in growth response to the higher P rate occurred among L. leucocephala isolines and G. sepium provenances. Shoot dry weight at low P varied from 1.30 to 3.01 g plant-1 for L. leucocephala and from 1.44 to 3.07 g plant-1 for G. sepium. Leucaena isolines had only half the root weight of G. sepium provenances yet produced approximately 90% of the shoot weight of the corresponding G. sepium treatments, i.e. more than a 2-fold difference in root/shoot ratios. Total P in shoots of G. sepium was some 85% greater than of the respective L. leucocephala isolines in corresponding treatments. Physiological phosphate use efficiency (g shoot/mg P in shoots) (PPUE) was not a simple reciprocal relation, being markedly lower at higher shoot % P and content. However, for the same shoot P both species produced the same shoot weight. Nevertheless, there were apparent genotypic differences within species in the root development, shoot P and PPUE. In another study, the numbers of rhizobia in the rhizosphere of L. leucocephala, nodulation, N2 fixation at five different levels of P were determined. The numbers of rhizobia in the rhizosphere of inoculated L. leucocephala during the first two weeks were lower when P was added but later became similar to those without added P. Nodules formed earlier than inoculated plants fertilized with P and in greater numbers (4- to 5-fold) and dry weights than in those without P. However, the percentage of N2 derived from fixation did not change with increasing levels of P application. These results suggest that the observed P effect did not operate via stimulated growth of rhizobia in the rhizosphere, nor through increased N2 fixation rate. The major effect appeared to be due to effects via plant growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00009192
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  • 7
    Electronic Resource
    Electronic Resource
    Influence of pruning management on P and N distribution and use efficiency by N2 fixing and non-N2 fixing trees used in alley cropping systems (1994)
    Springer
    Plant and soil 167 (1994), S. 219-226 
    Details
    ISSN: 1573-5036
    Keywords: Gliricidia sepiun ; low P soil ; N2 fixation ; Senna siamea ; S. spectabilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Pruning of hedgerow trees is an important management practice for the successful establishment of an alley cropping system. Although pruning affects biomass production, only meager evidence of this management on distribution of nutrients among the different plant organs after tree regrowth is available. This study examined the effect of pruning on the distribution and use efficiency of N and P in a N2 fixing leguminous tree species, Gliricidia sepium, and two non-N2 fixing leguminous tree species, Senna siamea and S. spectabilis, grown in a field on an Alfisol (low in P) at Fashola (Guinea Savanna Zone), Southwestern Nigeria. Four P rates, 0, 20, 40 and 80 kg P ha−1 as single superphosphate were used and management treatments included pruned versus unpruned plants. The 15N isotope dilution technique was used to measure N2 fixation in G. sepium. Partitioning of total P among different plant organs was influenced by plant species and pruning management, but was not affected by P application rates. The distribution of total P in the various plant organs followed that of dry matter yield while N partitioning had a different pattern. Pruned plants distributed about 118% more total P to branches and had a higher physiological P use efficiency (PPUE) than unpruned plants. Leaves were the biggest sink for total N and N allocation in the other plant organs was influenced by plant species and pruning management, G. sepium had relatively more of its total N and P partitioned into roots (about double that of the non-N2 fixing trees) but had a lower PPUE. Unpruned and pruned G. sepium derived 35 and 54% respectively of their total N from atmospheric N2, with about 54% of the fixed N2 being allocated to leaves and roots. Results showed that N and P pools turned over in the branches during plant regrowth after pruning but the causative factors associated with this phenomenon were not clear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00007948
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