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Assessment of the below ground contribution of field grown pea (Pisum sativum L.) to the soil N pool

Abstract : In order to use grain legumes as a means of N acquisition in cropping systems, estimates of biological N2 fixation, N balances and the N benefit for following crops need to be improved. These estimates remain unclear, mainly because of difficulties in assessing below ground N (BGN = Root N + N rhizodeposition), especially N rhizodeposition. The aim of my Ph.D. was to adapt and refine a 15N labelling method to measure the amount of N derived from rhizodeposition by a pea and to design a protocol for field studies. Two methods (split-root and cotton-wick) and a variety of labelling conditions were tested in the field and in the greenhouse. In addition, effects of water stress, N availability and sources of N nutrition (nitrogen fixation or inorganic N uptake) on this process were investigated on different pea varieties and isolines. The labelling frequency and concentration of the labelling solution were shown to influence the assessment of N rhizodeposition. However, results obtained with both methods were reliable when plants were labelled continuously with a diluted labelling solution. The 15N cotton-wick technique was easier to adapt and monitor in the field than the split-root method and was chosen for further field studies. The results suggest that N source and water stress have no specific effect on the proportion of total plant N allocated to the below ground parts. In the field, rhizodeposition represented around 90% of the total plant N. This should be taken into account when estimating N benefits from biological N2 fixation by a grain legume crop and for the prediction of N economies for succeeding crops in legume-based cropping systems.
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https://tel.archives-ouvertes.fr/tel-00433507
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Submitted on : Thursday, November 19, 2009 - 3:44:29 PM
Last modification on : Tuesday, June 2, 2020 - 2:32:03 PM
Long-term archiving on: : Thursday, June 17, 2010 - 9:01:31 PM

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  • HAL Id : tel-00433507, version 1

Citation

Stéphanie Mahieu. Assessment of the below ground contribution of field grown pea (Pisum sativum L.) to the soil N pool. domain_other. Université d'Angers, 2008. English. ⟨tel-00433507⟩

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