Field experiments were conducted to determine the effects of mother corms size and type of fertilizeron acquisition and use efficiency of nitrogen (N) and phosphorus (P) in Saffron, at Faculty of Agriculture,Ferdowsi University of Mashhad, Iran. The experiment designed as factorial-split with three replicates, 12main plots [mother corm size (4 g and lower, 4.1–8 g, 8.1-12 g and over 12 g) × fertilization (compostedcattle manure 25 t ha−1, chemical fertilizer (N 300 kg ha−1+ P 100 kg ha−1and control)] and two sub-plots (first and second year). In both years, the larger mother corms (8.1–12 g and more) resulted in agreater nitrogen content (g m−2) in daughter corms and the whole plant. In addition, acquisition and useefficiency of (N) and (P) were increased with increasing mother corms size. In both years, (N) and (P) useefficiency in composted cattle manure treatment was significantly higher than that of chemical fertilizer(by 21 and 61%, respectively). There was a positive and significant correlation between (N) use efficiencyand (P) use efficiency (R2= 0.98**) and between (N) harvest index and (P) harvest index (R2= 0.99**).

Keywords