Influence of phosphorus and nitrogen on photosynthetic parameters and growth in Vicia faba L.

The influence of phosphorus (P) and nitrogen (N) supply on biomass, leaf area, photon saturated photosynthetic rate (P_max), quantum yield efficiency (), intercellular CO₂ concentration (C_i), and carboxylation efficiency (CE) was investigated in Vicia faba. The influence of P on N accumulation, biomass, and leaf area production was also investigated. An increase in P supply was consistently associated with an increase in N accumulation and N productivity in terms of biomass and leaf area production. Furthermore, P increased the photosynthetic N use efficiency (NUE) in terms of P_max and . An increase in P supply was also associated with an increase in CE and a decrease in C_i. Under variable daily meteorological conditions specific leaf nitrogen content (N_L), specific leaf phosphorus content (P_L), specific leaf area (_L), root mass fraction (R_f), P_max, and remained constant for a given N and P supply. A monotonic decline in the steady-state value of R_f occurred with increasing N supply. _L increased with increasing N supply or with increasing N_L. We tested also the hypothesis that P supply positively affects both N demand and photosynthetic NUE by influencing the upper limit of the asymptotic values for P_max and CE, and the lower limit for C_i in response to increasing N.This revised version was published online in March 2005 with corrections to the page numbers.