The objective of this investigation was to study the influence of P fertilizer application on the quality and quantity of organic acid exuded by six cultivars of three lupin species: Lupinus albus L. (cultivars Minori and Nelly), Lupinus angustifolius L. (cultivars Borweta and Bordako) and Lupinus luteus L. (cultivars Borsaja and Borselfa). We also investigated the influence of the exudate collection medium (deionized water, 0.05 mM CaCl 2 solution) on the composition and the intensity of exuded organic acids in L. albus (cultivar Minori). Plants were grown in quartz sand with (+ P) and without (-P) fertilization for 21 days. The plants were removed carefully from the sand, the roots washed, and then allowed to release exudates into deionized water or 0.05 mM CaCl 2 solution twice for two hours or twice for four hours. Root length was measured. Root morphology was also reported. The results show that L. albus formed dense root clusters known as proteoid roots. The proteoid root formation was greatest under P deficiency conditions. A similar root system was observed in yellow lupin but this was less dense than in white lupin. Blue lupin did not form root clusters. Regardless of P nutrition, eight organic acids (citric, 2-oxoglutaric, malic, succinic, lactic, formic, acetic and fumaric acids) were identified in the collection solution of all six cultivars. The collection medium did not affect the amount and composition of released carboxylates within four hours. Exudates collected in CaCl 2 solution over an 8-hour period contained citric, malic and succinic acids as the most important organic acids. L. angustifolius showed the greatest average carboxylate efflux. Cultivated under P deficiency conditions, five cultivars increased their citrate exudation rate (on average, 67% for L. albus, 37% for L. angustifolius and 72% for L. luteus). exudation / Lupinus albus L. / organic acid / phosphorus nutrition / root Résumé-Effet de l'apport de phosphore sur l'exudation d'acides organiques de faible poids moléculaire par Lupinus albus L., Lupinus angustifolius L. et Lupinus luteus L. L'objectif de cette recherche était d'étudier l'influence d'une application de fertilisant phosphaté sur la qualité et la quantité d'acides organiques exudés par six variétés de trois espèces de lupins : Lupinus albus L. (variétés Minori et Nelly), Lupinus angustifolius L. (variétés Borweta et Bordako) et Lupinus luteus L. (variétés Borsaja et Borselfa). Nous avons également étudié l'influence du milieu de collecte d'exudat (eau déionisée, solution à 0,05 mM CaCl 2) sur la composition et l'intensité des acides origaniques exudés par L. albus (variété Minori). Les plantes ont été cultivées dans un sable quartzeux avec (+ P) et sans (-P) fertilisation pendant 21 jours. Les plantes étaient extraites du sable soigneusement, les racines lavées, puis conditionnées pour libérer les exudats dans l'eau déionisée ou la solution à 0,05 mM CaCl 2 deux fois pendant deux heures ou deux fois pendant quatre heures. La longueur des racines a été mesurée. La mor...
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