Assessment of the Impacts of Humic Acid Application and Mycorrhizal Fungi Inoculation on Flowering and Stigma Quality of Saffron under Two Irrigation Regimes

The shift toward sustainable production of medicinal plants highlights the importance of biological inputs. This study evaluated the effects of humic acid application, mycorrhizal inoculation, and two irrigation regimes on the reproductive growth, and quality of saffron (Crocus sativus L.). The experiment was conducted as split-split plot based on a randomized completely block design (RCBD) with three replications, where irrigation intervals (۲۰ and ۴۰ days) was the main plot, humic acid (۰ and ۵ kg ha⁻¹) was the sub-plot, and mycorrhizal inoculation (non-inoculated, Glomus mossea, and G. intraradices) was the sub-sub plot. The studied triats were number of flower, flowering rate, flower yield, petal yield, style yield, stigma yield and stigma qulity parameters (crocin, picrocrocin and safranal content). Results indicated that the triple interaction of experimental factors was significant on all studied traits. The shortest irrigation interval (۲۰ days) combined with humic acid application and G. mossea inoculation significantly increased fresh flower yield (۷۹.۶۳ g m⁻²), dry stigma yield (۰.۸۸ g m⁻²), style yield (۰.۲۲ g m-۲) and petal yield (۹.۸۸ g m-۲). Crocin content was highest (۲۷۴.۵, absorbance of ۱% aqueous solution at ۴۴۰ nm) under ۴۰-day irrigation intervals with humic acid and G. mossea inoculation, while safranal (۳۵.۸۰, absorbance at ۳۳۰ nm) and picrocrocin (۱۲۴.۵, absorbance at ۲۵۷ nm) improved under ۲۰-day irrigation intervals with humic acid and G. mossea. Conversely, extended irrigation intervals (۴۰ days) without humic acid and without mycorrhizal inoculation resulted in the lowest crocin and safranal content. Overall, the findings demonstrate that combined application of humic acid and inoculation with G. mossea under frequent irrigation optimizes both the quantity and quality of saffron. It was concluded that although the use of organic inputs is beneficial, the results of their single application can be different compared to their combined application. On the other hand, the interaction of two or more of these inputs can also vary depending on conditions, including the level of water availability and the type of mycorrhiza species.

کلیدواژه ها:

Crocin ، Crocus sativus ، Flowering rate ، Glomus mossea ، Picrocrocin ، Safranal