Osmoregulation and role of nitrate during regrowth after cutting of ryegrass (Lolium perenne) |
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Authors: | Alain Ourry Boris Gonzalez Jean Boucaud |
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Affiliation: | Lab. de Physiologie et Biochimie Végétales, Inst. de Recherches en Biologie Appliquée, Esplanade de la paix, Univ. de Caen, F-14032 Caen Cedex, France. |
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Abstract: | The osmotic role of nitrate during aftermath growth of Lolium perenne L. cv. Réveille was investigated. Plants were grown from seed in a controlled environment using a liquid medium with 1.0 m M NH4NO3 as nitrogen source. Eight-week-old plants were cut 4.0 cm above the root system and then harvested over a 14-day period of regrowth on the same initial nutrient solution, except that nitrate was 15N labelled. Throughout the experimental period, nitrate storage and reduction in roots were low. In stubble and especially in leaves, nitrate accumulated during the first 6 days of regrowth whereas nitrate reduction mainly occurred after this period. Analyses of carbohydrate, chloride and potassium contents in stubble and leaves showed that the accumulation of nitrate osmotically compensated for the decrease in soluble sugars during the first 6 days of regrowth. The cumulative osmotic potential of sugars, chloride and nitrate in differently treated plants was studied in stubble and leaves. Compared with uncut plants, the lower carbohydrate concentrations found in cut plants regrowing on 1.0 m M NH4NO3 were compensated for by an accumulation of nitrate. During aftermath growth on low nitrogen nutrition (0.2 m M NH4NO3), chloride replaced nitrate, supporting the proposed osmotic function of nitrate. It is concluded that nitrate is involved in the osmotic adjustment of ryegrass during regrowth after cutting. |
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Keywords: | Carbohydrates chloride growth Lolium perenne nitrates osmoregulation ryegrass |
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