Optimizing Corm Size and Density in Saffron (Crocus sativus L.) Cultivation by Central Composite Design

In order to determine the optimal use of corm size and density, an experiment was conducted by central composite design at the Research Station, the Ferdowsi University of Mashhad, Iran, during two growing seasons of 2008-2009 and 2009-2010. The treatments were designed based on low and high levels of corm size (3 and 7 g) and density (50 and 150 corm.m-2). Central point in each treatment was repeated 5 times and a total of 13 experimental treatments were designed. Economic yield, corm diameter, number of daughter corms, number of mother corms, number of flowers and fresh weight of flowers were measured as dependent variables, and the response surface of these variables to experimental factors was estimated by the polynomial regression model. The results indicated a positive effect of corm size and density on economic yield, corm diameter, dry weight of tunic, number of daughter corms, number of mother corms, number of flowers and fresh weight of flowers. The optimum level of corm size and density were 7 g and 250 plant.m-2, respectively.