Saffron Agronomy and Technology

Abstract Saffron, despite exhibiting relative resistance to drought stress, is known to experience reduced growth and yield under drought conditions due to its underdeveloped root system. This study aimed to investigate the potential of organic matter in mitigating the adverse effects of drought stress on saffron. A factorial experiment was conducted in a completely randomized design with three replications in the pot at the  University of Torbat Heydarieh in 2023-2024. Treatments included two levels of drought stress (non-stress (90% field capacity) and stress (50% field capacity)) and six levels of organic matter (a mixture of manure and leaf-soil in a 3:1 ratio) applied to the soil at rates of 0, 2. 5, 5, 10, 20, and 40%. The studied traits included leaf length, leaf weight, root weight, corm number, corm weight, water use efficiency, and the concentration and uptake of nitrogen, phosphorus, and potassium. Results showed that across all the OM treatments, drought stress had a negative impact on all growth traits. For instance, water deficit led to a 67% and 58% decrease in average corm weight and stigma DW compared to non-stress conditions, respectively. Nitrogen and potassium concentrations were higher under stress conditions across all organic matter levels, while phosphorus concentration was higher under non-stress conditions. The application of all organic matter levels increased the studied traits under both stress and non-stress conditions, with a more pronounced effect under stress. Under non-stress conditions, there was no significant difference between the 20% and 40% organic matter levels for the studied traits, while under drought stress, the highest values were obtained at the 40% organic matter level, with significant differences compared to other levels. The application of 40% organic matter increased the average corm weight from 13.2 g to 34.8 g under drought stress. At 0, 2. 5, 5, 10, and 20% organic matter levels, water use efficiency was significantly higher under non-stress conditions compared to water deficit, but at the 40% organic matter level, this index was significantly higher under drought stress (1. 82 kg.m-3) than under non-stress conditions (1. 48 kg.m-3). Overall, the results of this study indicated that the application of organic matter can significantly mitigate the negative effects of drought stress and lead to a significant increase in leaf and corm growth of saffron under these conditions. In pot or greenhouse planting, considering the economic efficiency, the application of 20% organic matter is recommended under drought stress conditions. For verification on a larger scale, this experiment needs to be evaluated for field conditions.