Nitrogen metabolism in roots and leaves of green bean plants exposed to different phosphorus doses

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 no3 - 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.