Determining effects of humic acid applications on saffron (Crocus sativus L.) corms planted in different types of soil substrates under ex vitro conditions

Saffron (Crocus sativus L.), a species of genus Crocus from Iridacea family, is an autotriploid sterile species that can only be propagated vegetatively using corms. The corms used in propagation constitute the most expensive input and the corms must reach a certain size in order to bloom. The aim of this study was to determine the effects of different types of substrates and different doses of humic acid on gain in size using small saffron corms (0.5 grams). The experiment was set up in randomized blocks according to the split plot design with 3 replications. Growing substrates (peat, loam, slag and soil) were placed in the main plots, and humic acid doses were placed in the sub plots using 0 (control), 0.65, 1.30, 2.60 g/m2. Percentage of emergence, total number of emergence/lot number of leaves/lot, leaf length (cm), number of corms/lot, corm weight (g/lot), and unit corm weight (g/corm) were evluated in the experiment. The differences in the mean values of all parameters in different growing substrates showed statistically significant variations. Leaf length, corm weight and unit corm weight were noted highest on peat with mean values of 47.64 cm, 41.51 g and 1.89 g, and lowest 35.0 cm on slag, 21.62 g and 0.97 g on loam substrate in the same sequence. It was determined that the small corms planted in peat substrate gained about 1.5–2 fold more weight compared to other substrates and showed increase in size as well. There was no significant difference between the 0.65 g/m2 and 1.30 g/m2 humic acid treatment comared to control treatment and lower gains were noted using 2.60 g/m2 humic acid. Peat substrate was the most suitable for the development and enlargement of small saffron coms compared to other substrates.