| Autor: |
Raddad, El Amin Yousif, Salih, Ahmed Ali, El Fadl, Mohamed Ahmed, Kaarakka, Vesa, Luukkanen, Olavi |
| Předmět: |
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| Zdroj: |
Plant & Soil; Aug2005, Vol. 275 Issue 1/2, p261-269, 9p, 3 Charts, 6 Graphs |
| Abstrakt: |
The symbiotic biological N2fixation by Acacia senegal was estimated using the 15N natural abundance ( δ 15N) procedure on eight provenances collected from different environments and soil types grown in a clay soil in the Blue Nile region, Sudan. Balanites aegyptiaca (a non-legume) was used as a non-N2-fixing reference plant to allow 15N-based estimates of the proportion of the Acacia N derived from atmospheric N2 (Ndfa) to be calculated. Results show variation in leaf δ 15N between A. senegal and the reference plant and among years. The relative δ 15N values (‰) were higher in B. aegyptiaca than in the N2-fixing acacia provenances. Provenances originally collected from clay soils fixed little N in the first year, but the amount fixed increased as the trees aged. All provenances showed a decrease in δ 15N with age. The Ndfa varied between 24% (Mazmoom provenance) and 61% (Rahad provenance) 4 years after planting. There was no significant difference in δ 15N between provenance groups based on soil type or rainfall at original growing site. The amount of Ndfa increased significantly with age in all provenances. The above-ground contribution of fixed N to foliage growth in a 4-year-old A. senegal was highest in the Rahad sand–soil provenance (46.7 kg N ha−1) and lowest in the Mazmoom clay-soil provenance (28.7 kg N ha−1). Our study represents the first use of the δ 15N method for estimating the N input by A. senegal to the clay plain soils of the gum belt in the Sudan. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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