Nodule senescence in Phaseolus vulgaris L.
1988
Hungria, M. | Franco, A.A. (EMBRAPA, Sao Paulo, Rio de Janeiro (Brazil))
The effects of bean (Phaseolus vulgaris L.) cultivars and Rhizobium strains on nodule senescence were studied under glasshouse conditions. Four common bean cultivars (Carioca 80, CNPAF-2234, Rio Tibagi and Negro Argel) were inoculated separately with 4 Rhizobium strains (C05, CNPAF 146, SEMIA 487 and V-23), and harvested at 35, 46 and 55 days after emergence. Nitrogenase activity, total N transported and ureide content in the xylem sap and number of pink nodules began to decline soon after flowering, showing an early process of nodule senescence. Nodule colour and texture, as well as the rates of acetylene reduction and N transported in the xylem sap at different harvest, were affected both by plant cultivar and Rhizobium strain, and the symbiotic combinations more promising for delayed nodule senescence showed a higher proportion of active pink nodules during the reproductive growth phase of the plants
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