Effects of photosynthate manipulation on biological nitrogen fixation in common bean plants
Two experiments were performed, under greenhouse conditions, to investigate the effect of availability of carbon to the nodules on biological nitrogen fixation in common bean plants. Removal of flowers initially increased nitrogenase activity, relative efficiency of electrons for nitrogenase (RE) and rate of nitrogen translocation in the xylem sap, but within ten days all these parameters decreased due to an acceleration of nodule senescence. The removal of 50% of the leaves at flowering decreased nitrogenase activity, RE and N translocation in the xylem sap, but after ten days the plants began recover in these parameters due to the production of new leaves, which did not happen when the leaves where removed at mid-pod filling stage. The stem ringing, hampering translocation of photosynthates to the nodules, decreased nitrogenase activity, RE, and N transport in xylem sap, but the decrease in nitrogenase activity occurred 24 hours after ringing, indicating that in bean roots there is a considerable quantity of stored substrates for N2 fixation.
| Main Authors: | , |
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| Format: | Digital revista |
| Language: | por |
| Published: |
Pesquisa Agropecuaria Brasileira
2014
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| Online Access: | https://seer.sct.embrapa.br/index.php/pab/article/view/14650 |
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| Summary: | Two experiments were performed, under greenhouse conditions, to investigate the effect of availability of carbon to the nodules on biological nitrogen fixation in common bean plants. Removal of flowers initially increased nitrogenase activity, relative efficiency of electrons for nitrogenase (RE) and rate of nitrogen translocation in the xylem sap, but within ten days all these parameters decreased due to an acceleration of nodule senescence. The removal of 50% of the leaves at flowering decreased nitrogenase activity, RE and N translocation in the xylem sap, but after ten days the plants began recover in these parameters due to the production of new leaves, which did not happen when the leaves where removed at mid-pod filling stage. The stem ringing, hampering translocation of photosynthates to the nodules, decreased nitrogenase activity, RE, and N transport in xylem sap, but the decrease in nitrogenase activity occurred 24 hours after ringing, indicating that in bean roots there is a considerable quantity of stored substrates for N2 fixation. |
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