Interrelationships between nitrogen supply and photosynthetic parameters in Vicia faba L.

Abstract

We determined for Vicia faba L the influence of nitrogen uptake and accumulation on the values of photon saturated net photosynthetic rate (P Nmax), quantum yield efficiency (α), intercellular CO 2 concentration (Ci), and carboxylation efficiency (C e). As leaf nitrogen content (NL) increased, the α converged onto a maximum asymptotic value of 0.0664±0.0049 μmol(CO2) μmol(quantum)-1. Also, as NL increased the Ci value fell to an asymptotic minimum of 115.80±1.59 μmol mol-1, and Ce converged onto a maximum asymptotic value of 1.645±0.054 μmol(CO2) m -2 s-1 Pa-1 and declined to zero at a N L-intercept equal to 0.596±0.096 g(N) m-2. α fell to zero for an NL-intercept of 0.660±0.052 g(N) m -2. As NL increased, the value of PNmax converged onto a maximum asymptotic value of 33.400±2.563 μmol(CO 2) m-2 s-1. PN fell to zero for an NL-intercept of 0.710±0.035 g(N) m-2. Under variable daily meteorological conditions the values for NL, specific leaf area (δL), root mass fraction (Rf), P Nmax, and α remained constant for a given N supply. A monotonic decline in the steady-state value of Rf occurred with increasing N supply. δL increased with increasing N supply or with increasing NL.