Study of flower and stigma yield of saffron as affected by potassium and zinc fertilizers in Khorasan Razavi Province

Saffron (Crocus sativus L.) is considered as the most expensive spice in the world. Although Iran has the highest world saffron production, but its yield is less compared with other producing countries. The purpose of this research was to evaluate the effect of potassium and zinc application on flower yield and qualitative characteristics of saffron stigma. This study has been implemented based on the soil analysis results at south of Sabzevar city (in west of Khorasan Razavi province) during growing season of 2012 2013. Experiments had been performed as factorial layout based on a randomized complete block design with three replications. Three levels of potassium (0, 100 and 200 kg.ha-¹) and three levels of zinc (0, 25 and 50 kg ha-¹) was investigated as treatments. The measured responses were fresh weight of flowers and stigma, stigma dry weight and number of flowers for saffron. Then data were analyzed by using SPSS software. The obtained results showed that consumption of potassium has no significant effect on the measured characteristics. But consumption of 200 kg ha-¹ potassium sulfate lad to %5.5 numbers of flowers, %5.6 weights of flower, %10 fresh weight of stigma and %8.5 dry weights of stigma increase in flower number compared to control.
While the impact of different levels zinc consumption were significant on studied trait. Consumption of 25 kg ha-¹ zinc sulfate increased % 65 numbers of flower, %84 weight of flowers, %73 fresh weight of stigma and %150 dry weight of stigma to control. However, by using of 50 kg Zinc sulfate, not only measured characteristics didn’t increase, but also saffron yield was lower than control. As regards the many soils in Khorasan province (more than %80) are faced with zinc deficiency, can be concluded that zinc consumption is so necessary to improve yield of saffron.