To investigate the effects of mycorrhizal inoculation and humic acid application on the growth of

daughter corms of saffron (Crocus sativus L.) under two irrigation regimes, an experiment was conducted during the 2016–2017 growing season at the Research Farm of the Faculty of Agriculture, Sarayan, University of Birjand. The experiment was arranged as a split-split plot based on a randomized complete block design with three replications. Irrigation interval (20 and 40 days) was assigned to main plots, humic acid application (0 and 5 kg ha⁻¹) to subplots, and mycorrhizal inoculation (Glomus mosseae, G. intraradices, and non-inoculated control) to sub-subplots. Irrigation regime significantly affected total leaf weight, scale weight, and the number of daughter corms in different weight classes; humic acid influenced total daughter corm number, scale weight, corm weight, and daughter corm distribution across weight classes; and mycorrhizal inoculation impacted total daughter corm weight per plant, number of flower buds per corm, scale weight, and daughter corm counts in various weight categories. The highest leaf weight and dry stigma yield (1.7 g.m2) were obtained under 20-day irrigation intervals with G. mosseae inoculation and humic acid application, whereas the lowest values occurred under 40-day intervals without inoculation or humic acid. The maximum number of daughter corms (5.61 per plant) and flower buds (14.6 per corm) were recorded under combined G. mosseae inoculation and humic acid at 20-day irrigation. Daughter corms were predominantly distributed in the <4 g weight class across treatments, with the highest number of large corms (8–12 g) observed under 20-day irrigation with humic acid and G. mossea, although the highest number of small corms was also recorded in the above treatment. Overall, humic acid application and mycorrhizal inoculation relatively enhanced leaf weight, dry stigma yield, and daughter corm weight and number under the 20-day irrigation regime.