Water shortage and associated changes in organic nitrogen betweenPappophorum caespitosum(Gramineae) provenances |
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Authors: | SO Trione JB Cavagnaro |
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Institution: | Instituto Argentino de Investigaciones de las Zonas Aridas (IADIZA), P.O. Box 507, (5500), Mendoza, Argentina |
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Abstract: | Three provenances ofPappophorum caespitosum, a forage native grass from the temperate arid region of Argentina, were studied to gain a physiological knowledge of the seasonal organic N status in response to adequate water supply and water stress conditions; and to assess the extent to which variations in the N status between these provenances arise under different water regimes. Plant part samples were analysed for free and bound organic N fractions. Water shortage resulted in a significant depression of plant growth in all provenances. Total N concentration declined along the annual cycle in both water treatments, but it was higher under water stress. The size of the free N pool was very large, suggesting that it may act like an osmoticum. Nitrogen use efficiency increases along the growing period, while the rate of N intake and the specific leaf N content decrease. Variability was found between provenances in most of the physiological and biochemical traits examined under both water regimes. |
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Keywords: | Pappophorum caespitosum N status free N pool water stress arid land |
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