Application of fertilizers for increased saffron yield

Research was undertaken to determine the response of newly planted saffron to the application of different levels of nitrogen (0, 50 and 100 kgN.ha(-1 ).year(-1)), phosphorus (0, 25, and 50 kg P2O5.ha(-1).year(-1)), and compos ted cow manure (0, 20, and 40 tons.ha(-1).year(-1)) in terms of fresh flowe r weight (FFW), saffron yield (SY) and leaf biomass. The experiments were c onducted in Birjand, and Ghaen, Khorasan province, Iran, from 1991 to 1993. Significant differences were found between the two locations and among the years within each location for FFW and SY. Averaged over all treatments an d years, mean values for FFW and SY were 644.3 and 9.1 kg.ha(-1), respectiv ely, at Birjand, and 296.0 and 3.7 kg.ha(-1), respectively, at Ghaen. At Bi rjand, mean FFW in the three consecutive years was 229.0, 796.2, and 907.8 kg.ha(-1) and mean SY was 3.4, 10.6, and 13.4 kg.ha(-1). The corresponding means at Ghaen were 87.5, 225.9, and 574.7 kg.ha(-1) for FFW and 1.3, 3.2, and 6.7 kg.ha(-1) for SY. Simple correlation coefficients between FFW and S Y were positive and highly significant. At both locations, FFW and SY incre ased significantly from year to year. The rate of increase, however, decrea sed with the age of the saffron field because of overcrowding of new corms. Different combinations of fertilizers had either a negative or nonsignific ant effect on FFW and SY. The application of phosphorus fertilizer did not result in increased FFW and SY. The application of 40 tons.ha(-1) of cow ma nure in the first year followed by no fertilizer in the second year and by 20 tons.ha(-1) in the third year increased FFW and SY at Birjand. The use o f 100 kg.ha(-1) nitrogen only in the third year also increased FFW and SY a t Birjand. At Ghaen, only the application of 50 kg.ha(-1) nitrogen in the t hird year resulted in increased FFW and SY.