Effects of nutrition management on saffron (.Crocus sativus L) stigma and flower yield

The current study investigates the effects of different levels of nutrient and Fe foliar application on stigma and flower yield of saffron. A field experiment was conducted as a factorial layout based on complete randomized block design with three replications at the Agricultural Research Station, the Ferdowsi University of Mashhad, Iran in 2012-2014. The experimental factors included chemical fertilizer (NPK) at three levels (0-0-0, 30-15-30, 60-30-60 kg.ha-1), vermicompost at two levels (0, 4 t.ha-1), humic acid at two levels (0, 5 kg.ha-1) and two levels of Fe foliar spraying concentration (0, 0.08 µmol). The number of flower, fresh and dry weight of stigma and flower yield were determined for two years. The results of analysis of variance revealed that the studied experimental factors had a significant effect on quantitative traits of saffron flowers and stigma. There was a significant difference between the chemical fertilizer levels on flower number and stigma dry weight. The highest flower number (165.m-2) and stigma dry weight (1.16 g.m-2) were obtained in the NPK fertilizer (60-30-60) treatment. Moreover, the interaction between chemical fertilizer and other factors was significant and led to the improvement of the number of flowers and stigma dry weight per unit of area. Stigma dry weight increased in vermicompost, humic acid and Fe foliar application compared with control (3.3 1.3 and 2.7 percent, respectively). However, two-way interaction of factors did not affect the number of flower.m-2. In addition, the three-way interaction of humic acid, vermicompost and chemical fertilizer significantly affected stigma dry weight.m-2. Four-way interaction of all studied factors including year, vermicompost, chemical fertilizer and Fe foliar spraying were significant on flower dry weight and stigma fresh and dry weight per unit area when compared with control (p≤0.05). Quantitative traits of flower and stigma in the second year improved in comparison with the first year. The interaction effects between year and chemical fertilizer was significant on the traits that were studied.