L. Seedlings (l + seedling)

Distribution by Scientific Domains


Selected Abstracts


Control of Nitrate Uptake by Phloem-Translocated Glutamine in Zea mays L. Seedlings

PLANT BIOLOGY, Issue 4 2002
P. Pal'ove-Balang
Abstract: The putative role of glutamine, exported from leaves to roots, as a negative feedback signal for nitrate uptake was investigated in Zea mays L. seedlings. Glutamine (Gln) was supplied by immersion of the tip-cut leaves in a concentrated solution. Nitrate (NO3,) uptake was measured by its depletion in amino acid-free medium. The treatment with Gln resulted in a strong inhibition of nitrate uptake rate, accompanied by a significant enrichment of amino compounds in root tissue. The effect of N-availability on NO3, uptake was determined in split-root cultures. The plants were subjected to complete or localized N supply. Inducible NO3, uptake systems were also induced in N-deprived roots when the opposite side of the root system was supplied with KNO3. The inhibitory effect of Gln was unaffected by localized N supply on one side of the split-root. The potential role of Gln in the shoot-to-root control of NO3, uptake is discussed. [source]


Effects of Drought on the Competitive Interference of an Early Successional Species (Rubus fruticosus) on Fagus sylvatica L. Seedlings: 15N Uptake and Partitioning, Responses of Amino Acids and other N Compounds

PLANT BIOLOGY, Issue 3 2002
M. N. Fotelli
Abstract: We assessed the role of water availability as a factor regulating the ability of beech seedlings to cope with competitive interference for nitrogen resources by an early successional species (Rubus fruticosus). A glasshouse experiment was performed with two levels of interference (beech with and without R. fruticosus) and three levels of irrigation (high, intermediate, none). 15N uptake and partitioning of both species, and composition of N pools in leaves, roots and phloem of beech, were determined. Under all irrigation regimes, 15N uptake by beech seedlings decreased when grown together with R. fruticosus. R. fruticosus had higher 15N uptake rates than beech, under all water supply levels. When irrigation was reduced, a substantial decrease in 15N uptake of beech seedlings and a concurrent increase in 15N uptake by R. fruticosus were observed. Interference by R. fruticosus and low irrigation also affected the 15N partitioning in beech seedlings and resulted in reduced allocation of 15N to the roots. The combination of competitive interference and lack of irrigation led to an increase in soluble non-protein N in roots and leaves of beech, due to protein degradation. This response was attributed to an increase in levels of amino acids serving as osmoprotectants under these conditions. The concentration of proline in leaves of beech was negatively correlated to shoot water potential. A competition-induced reduction of total N in leaves of beech under high and intermediate irrigation was found. These results illustrate (1) the advantage of R. fruticosus in terms of N uptake when compared to young beech, particularly under inadequate water supply, and (2) the changes in N composition of beech seedlings in order to cope with reduced soil water and interference by R. fruticosus. [source]


Establishment of Retama sphaerocarpa L. seedlings on a degraded semiarid soil as influenced by mycorrhizal inoculation and sewage-sludge amendment

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 5 2004
María del Mar Alguacil
Abstract A field experiment was carried out to evaluate the effectiveness of mycorrhizal inoculation with three arbuscular mycorrhizal (AM) fungi (Glomus intraradices Schenck & Smith, Glomus deserticola (Trappe, Bloss. & Menge), and Glomus mosseae (Nicol & Gerd.) Gerd. & Trappe) and the addition of composted sewage sludge (SS) with respect to the establishment of Retama sphaerocarpa L. seedlings, in a semiarid Mediterranean area. Associated changes in soil chemical (nutrient content and labile carbon fractions), biochemical (enzyme activities), and physical (aggregate stability) parameters were observed. Six months after planting, both the addition of composted SS and the mycorrhizal-inoculation treatments had increased total N content, available-P content, and aggregate stability of the soil. Values of water-soluble C and water-soluble carbohydrates were increased only in the mycorrhizal-inoculation treatments. Rhizosphere soil from the mycorrhizal-inoculation treatments had significantly higher enzyme activities (dehydrogenase, protease-BAA, acid phosphatase, and ,-glucosidase) than the control soil. In the short-term, mycorrhizal inoculation with AM fungi was the most effective treatment for enhancement of shoot biomass, particularly with G. mosseae (about 146% higher with respect to control plants). The addition of the composted SS alone was sufficient to restore soil structural stability but was not effective with respect to improving the performance of R. sphaerocarpa plants. Besiedlung eines degradierten semiariden Bodens mit Retama sphaerocarpa L.-Setzlingen, beeinflusst durch Mykorrhiza-Inokulation und Klärschlammzugabe Ein Feldversuch wurde durchgeführt, um den Effekt einer Inokulation mit drei arbuskulären Mykorrhizapilzen (AM) (Glomus intraradices Schenck & Smith, Glomus deserticola (Trappe, Bloss. & Menge) und Glomus mosseae (Nicol & Gerd.) Gerd. & Trappe) einerseits und der Zugabe von kompostiertem Klärschlamm (SS) andererseits auf die Besiedlung von Retama sphaerocarpa L.-Setzlingen in einem mediterranen semiariden Gebiet zu untersuchen. Es wurden chemischer Nährstoffgehalt, labile C-Fraktion, biochemische Enzymaktivitäten und physikalische Bodenparameter (Aggregatstabilität) untersucht. Sechs Monate nach der Pflanzung erbrachten beide Behandlungen , die Zugabe von kompostiertem Klärschlamm und die Mykorrhiza-Inokulation , Steigerungen des Gesamtstickstoff-Gehaltes, des verfügbaren Phosphor-Gehaltes sowie der Aggregatstabilität des Bodens. Wasserlöslicher Kohlenstoff und wasserlösliche Kohlenhydrate waren nur nach Mykorrhiza-Inokulation erhöht. Boden aus der Rhizosphäre, der mit Mykorrhizapilzen inokuliert wurde, zeigte signifikant höhere Enzymaktivitäten (Dehydrogenase, Protease-BAA, saure Phosphatase und ,-Glucosidase) als der Kontrollboden. In der kurzen Periode war die Inokulation mit AM-Pilzen die effektivste Behandlung bei der Bildung von Sprossbiomasse, speziell bei G. mosseae (eine um über 146,% höhere Biomasse im Vergleich zu den Kontrollpflanzen). Die Zugabe von kompostiertem Klärschlamm allein war ausreichend, die Stabilität der Bodenstruktur wiederherzustellen, aber sie war nicht effektiv hinsichtlich der Entwicklung der R. sphaerocarpa -Pflanzen. [source]


Control of Nitrate Uptake by Phloem-Translocated Glutamine in Zea mays L. Seedlings

PLANT BIOLOGY, Issue 4 2002
P. Pal'ove-Balang
Abstract: The putative role of glutamine, exported from leaves to roots, as a negative feedback signal for nitrate uptake was investigated in Zea mays L. seedlings. Glutamine (Gln) was supplied by immersion of the tip-cut leaves in a concentrated solution. Nitrate (NO3,) uptake was measured by its depletion in amino acid-free medium. The treatment with Gln resulted in a strong inhibition of nitrate uptake rate, accompanied by a significant enrichment of amino compounds in root tissue. The effect of N-availability on NO3, uptake was determined in split-root cultures. The plants were subjected to complete or localized N supply. Inducible NO3, uptake systems were also induced in N-deprived roots when the opposite side of the root system was supplied with KNO3. The inhibitory effect of Gln was unaffected by localized N supply on one side of the split-root. The potential role of Gln in the shoot-to-root control of NO3, uptake is discussed. [source]


Effects of a 60 Hz magnetic field on photosynthetic CO2 uptake and early growth of radish seedlings

BIOELECTROMAGNETICS, Issue 8 2004
Akira Yano
Abstract Photosynthetic CO2 uptake rate and early growth parameters of radish Raphanus sativus L. seedlings exposed to an extremely low frequency magnetic field (ELF MF) were investigated. Radish seedlings were exposed to a 60 Hz, 50 ,Trms (root mean square) sinusoidal magnetic field (MF) and a parallel 48 ,T static MF for 6 or 15 d immediately after germination. Control seedlings were exposed to the ambient MF but not the ELF MF. The CO2 uptake rate of ELF MF exposed seedlings on day 5 and later was lower than that of the control seedlings. The dry weight and the cotyledon area of ELF MF exposed seedlings on day 6 and the fresh weight, the dry weight and the leaf area of ELF MF exposed seedlings on day 15 were significantly lower than those of the control seedlings, respectively. In another experiment, radish seedlings were grown without ELF MF exposure for 14 d immediately after germination, and then exposed to the ELF MF for about 2 h, and the photosynthetic CO2 uptake rate was measured during the short term ELF MF exposure. The CO2 uptake rate of the same seedlings was subsequently measured in the ambient MF (control) without the ELF MF. There was no difference in the CO2 uptake rate of seedlings exposed to the ELF MF or the ambient MF. These results indicate that continuous exposure to 60 Hz, 50 ,Trms sinusoidal MF with a parallel 48 ,T static MF affects the early growth of radish seedlings, but the effect is not so severe that modification of photosynthetic CO2 uptake can be observed during short term MF exposure. Bioelectromagnetics 25:572,581, 2004. © 2004 Wiley-Liss, Inc. [source]