A role for nitrogen reserves in forage regrowth and stress tolerance |
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Authors: | J J Volenec A Ourry B C Joern |
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Institution: | Dept of Agronomy, Purdue Univ, West Lafayette, IN 47907-1150, USA;Labortoire de Physiologie et de Biochimie Vegetales. Institute de Recherche en Biologic Applique, Univ. Caen, F-14032, Caen, Cedex, France. |
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Abstract: | Carbohydrate accumulation and utilization during shoot regrowth after defoliation and winter has been studied extensively in most species used as forage. However, recent work suggests that N reserves found in vegetative tissues also are important for defoliation tolerance and winter hardiness. Results suggest that these N reserves constitute an alternative N source used when N2 fixation and/or mineral N uptake are reduced. 15N labelling experiments indicate that a large proportion of herbage N is derived from N reserves mobilized from stem bases or roots to developing leaves and shoots. Amino acids and specific proteins (i.e. vegetative storage proteins, VSPs) are deposited in roots and stem bases and, in the case of VSPs, are degraded rapidly after defoliation. Identification and characterization of VSPs will increase our understanding of the role N reserves play in stress tolerance and may lead to innovative approaches for improving forage persistence and productivity. |
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Keywords: | Alfalfa carbohydrate reserves clover defoliation tolerance Lolium Medicago ryegrass Trifolium vegetative storage protein winter hardiness |
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