Interaction between nitrate assimilation in shoots and nitrate uptake by roots of soybean (Glycine max) plants: Role of carboxylate
| Autor: | C. Grignon, Nicole Grignon, Bruno Touraine |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
inorganic chemicals
0106 biological sciences 0303 health sciences Chemistry organic chemicals Nitrogen assimilation fungi food and beverages Plant physiology Xylem 01 natural sciences 03 medical and health sciences Horticulture chemistry.chemical_compound Botany Shoot Phloem transport Phloem Carboxylate 030304 developmental biology 010606 plant biology & botany Transpiration |
| Zdroj: | Plant Nutrition — Physiology and Applications ISBN: 9789401067515 |
| Popis: | The rates of accumulation of K+, NO3 − and reduced N (Nr) in shoots, relative to that of Ca2+, were compared to the ratios K+/Ca2+, NO3 −/Ca2+ and Nr/Ca2+ in the xylem sap of NO3 −-fed soybean plants in order to estimate the xylem transport of K+, NO3 − and Nr. Then, phloem transport of K+ and Nr could be calculated. The quantification of NO3 − flux in the xylem and NO3 − accumulation in shoots allowed us to estimate the contribution of roots and shoots in the reduction of NO3 −. Subtraction of the inorganic anion content from the main cation content estimated the accumulation of carboxylate anions (R−). The export of R to roots was obtained by subtracting R accumulation in shoots from the theoretical production associated to NO3 − reduction in these organs. The OH− net excretion in the medium was monitored. Alkalinization of the medium was stopped by interruption of phloem conduction to the roots, and was not restored by glucose addition to the medium. Excretion of 14C by roots after incorporation of 14CO2 in leaves was greater than that from urea-fed plants. These results suggest that the OH− equivalents excreted in the medium originated from R produced in shoots. The supply of K-malate to the shoots via the transpiration flow stimulated NO3 − uptake. This result indicates that the circulation of R− to the roots could be a mechanism by which NO3 − assimilation in shoots controls NO3 − uptake by roots. |
| Databáze: | OpenAIRE |
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