Resumo

SANCHEZ, E. et al. Nitrogen metabolism in roots and leaves of green bean plants exposed to different phosphorus doses. Phyton (B. Aires) [online]. 2009, vol.78, n.1, pp.11-16. ISSN 1851-5657.

The objective of this work was to determine the effect of different P doses on nitrogen assimilation in roots and leaves of green beans plants (Phaseolus vulgaris L. cv. Strike). Phosphorus was applied in the nutrient solution as H₃PO₄, at the nutrient doses of: P1 = 0.40 mM; P2 = 0.80 mM; P3 = 1.60 mM; P4 = 3.20 mM; P5 = 4.80 mM, and P6 = 6.40 mM P. Our results indicate that both P toxicity and deficiency gave similar responses to N assimilation. Phosphorus and NO_{3 -} interacted on the absorption and translocation processes affecting N assimilation. The deficiency (P1), and toxicity (P6) treatments, diminished root absorption of NO₃- in 15% and 36%, respectively, respect to the optimum dose (P3), thus reducing nutrient availability for assimilation. This result may explain the minimum enzymatic activities observed in NO₃ - assimilation in P1 and P6. The minimum N assimilation observed in these treatments will eventually translate into a minimum synthesis of major N organic compound involved in plant growth and development. This will lead to a reduced plant biomass production and productivity of green beans plants.

Palavras-chave : Phaseolus vulgaris L.; Nitrogen metabolism; Green bean; Phosphorus; Deficiency; Toxicity.

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