Effects of high temperature on nodulation and nitrogen fixation by Phaseolus vulgaris L. |
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Authors: | Mariangela Hungria Avílio Antônio Franco |
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Institution: | (1) EMBRAPA-CNPSo, Caixa Postal 1061, CEP 86001-970 Londrina, PR, Brazil;(2) EMBRAPA-CNPBS, Caixa Postal 74505, CEP 23851 Seropédica, RJ, Brazil |
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Abstract: | Screening of Rhizobium leguminosarum bv. phaseoli strains showed some that were able to nodulate common beans (Phaseolus vulgaris L.) at high temperatures (35 and 38°C/8 h/day). The nodulation ability was not related to the capability to grow or produce
melanin-like pigment in culture media at high temperatures. However, nodules formed at high temperatures were ineffective
and plants did not accumulate N in shoots. Two thermal shocks of 40°C/8 h/day at flowering time drastically decreased nitrogenase
activity and nodule relative efficiency of plants otherwise grown at 28°C. Recovery of nitrogenase activity began only after
seven days, when new nodules formed; total incorporation of N in tops did not recover for 2 weeks. Non-inoculated beans receiving
mineral N were not affected by the thermal shock, and when growing continuously at 35 or 38°C had total N accumulated in shoots
reduced by only 18%. |
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Keywords: | common bean nitrogenase nodule senescence Rhizobium |
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