Saffron Agronomy and Technology

Abstract Although saffron (Crocus sativus L.), as one of the most important medicinal-spice species with low water requirement and high economic value, is not tolerant to salinity, evidences show that it is not highly sensitive to salinity either; however, information about saffron response to salinity at the field scale is very limited. The present study aimed to investigate the effect of irrigation with different levels of electrical conductivity (2, 5, 8, and 11 dS m-1) and different amounts of nitrogen (0, 25, 50, and 100 kg ha-1) on saffron stigma yield and changes in soil salinity. The results showed that stigma yield decreased significantly with increasing salinity in both years, especially in the second year; so that in the second year, no plants grew in the 11 dS m-1 treatment. The reduction in yield due to the highest salinity level in the first and second years was 75.3% and 80.9%, respectively. Only in the second year did nitrogen have a significant effect on stigma yield; the highest yield was obtained at salinities of 2 and 5 dS m-1 from the 50 kg N ha-1 treatment and at salinity of 8 dS m-1 from the 25 kg N ha-1 treatment. The effect of saline irrigation on the electrical conductivity of the saturated soil extract (ECe) was observed from 50 days after planting (DAP), and over time up to 150 DAP, water salinity treatments (except 2 dS m-1) led to an increase in ECe at two depths of 0 to 30 and 30 to 60 cm. At this time, the average ECe of the two depths in irrigation water treatments with salinities of 2, 5, 8 and 11 dS m-1 was equal to 0.3, 1.8, 10.9 and 13.9 dS m-1, respectively. In the second year, the treatments maintained the differences made in the first year relatively evenly throughout the growing season. Given the good regression relationship between the EM38 and ECe readings, the apparent salinity (ECa) could be estimated using the EM38. The differences between ECa in nitrogen and salinity treatments were very pronounced, with the highest ECa being obtained from the 11 dS m-1 treatment. Overall, the results showed that semi-saline water could be used for saffron cultivation with a slight yield reduction, however, irrigation and nutrition management should be carefully observed. In low salinity, 50 kg N ha-1 and in medium salinity, 25 kg N ha-1 is suitable for improving saffron yield. By observing the appropriate leaching fraction for saline conditions and the stability of soil salinity, it is expected that soil salinity at the end of the growing season will be 1.4 times the average of irrigation water, and soil salinity at the end of the saffron growing season will be between 0.94 and 1.44 times that at the beginning of the season.

Abstract 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.

Abstract Considering the impact of climatic parameters, particularly temperature and precipitation, on the growth, yield, and quality of saffron, this study aimed to investigate the flower and stigma yield along with some quantitative traits of saffron under the influence of climatic factors and agricultural management in ten counties of Khorasan Razavi Province (including Bajestan, Bakharz, Bardaskan, Gonabad, Quchan, Mashhad, Mahvalat, Taybad, Torbat-e Heydarieh, and Zaveh) through a questionnaire survey conducted over two years (2022 and 2023). The studied traits included time to flowering onset, flowering duration, flower yield, stigma yield, and stigma harvest index in saffron. Cluster analysis was performed to group cities. The results indicated that the simple effects of farm age, number of irrigations, summer irrigation, climate, year, and the interaction between climate and year were significant (p ≤ 0.05) for most flowering indices. The flowering duration ranged from 12.2 to 17.5 days in 2022 and from 8.2 to 12.1 days in 2023. The longest flowering duration in both years was recorded in Zaveh and Bakharz, while Bajestan had the shortest. The greatest and least reduction in flowering duration from the first to the second year were observed in Taybad and Zaveh, respectively. The flower yield ranged from 278.5 to 799.95 kg.ha^-1 in 2022 and from 152.1 to 360.8 kg.ha^-1 in 2023; in both years, Taybad and Bardaskan had the highest and lowest yields, respectively. The reduction in flower yield from the first to the second year ranged from 34% to 67%, with Zaveh and Bajestan showing the highest and lowest reductions, respectively. Correlation analysis between climatic parameters and saffron yield revealed a highly significant correlation between yield and the average August temperature, as well as between yield and the total February. As the average August temperature increased, yield decreased; conversely, increased in February precipitation improved yield. Since replenishment of photosynthetic material occurs in daughter corms during winter, rainfall during the growing season is crucial. All flowering indices were higher in counties with cooler climates compared to those with warmer climates. Furthermore, the decline in flower and stigma yield in the second year was less pronounced in warmer counties due to lower cold damage. Overall, it is recommended to adopt ecological intensification strategies, such as soil shading during hot summers, planting large corms at high density per unit area, and reducing the exploitation period, to mitigate the effects of climate change.

Abstract The aim of this research was to investigate the quantitative and qualitative characteristics of saffron (Crocus sativus L.) under the influence of corm inoculation with beneficial microorganisms and vermicompost in a randomized complete block design with three replications during two agricultural years, 2019-2020 and 2020-2021, at the Research Farm of Urmia University, Iran. The involved factors included 1) control without using phosphorus chemical fertilizer and without corm inoculation, consumption of 100% of the recommended phosphorus chemical fertilizer based on soil test, and without inoculation, corm inoculation with Pseudomonas fluorescens, corm inoculation with Glomus etunicatum, vermicompost (10 t.ha^-1 at planting time), corm inoculation with P. fluorescens + G. etunicatum, corm inoculation with P. fluorescens + vermicompost, corm inoculation with G. etunicatum + vermicompost, and corm inoculation with P. fluorescens + G. etunicatum + vermicompost. Based on the results of this study, the combined treatment of vermicompost with Pseudomonas and mycorrhiza had a positive, significant effect on the quantitative and qualitative yields of saffron. In most of the studied traits, the highest values ​​were observed in the combined biofertilizer treatments, although this difference was not significant for some traits with the chemical phosphorus fertilizer. The highest fresh and dry weight of corms was observed in the combined treatment of vermicompost with Pseudomonas (6.3 and 1.8 kg.m^-2) and mycorrhiza treatment (5.89 and 1.71 kg.m^-2), and the highest yield of stigma fresh and dry weight was observed in the combined treatment of vermicompost with Pseudomonas (0.018 and 0.007 g.m^-2) and also mycorrhiza treatment (0.017 and 0.005 g.m^-2). The results showed that the fresh and dry yields of saffron style in biofertilizer treatments, and in the combination of biofertilizer with vermicompost, were significantly higher than those in the phosphorus chemical fertilizer and control treatments. The highest crocin content was obtained in the combined treatment of vermicompost with mycorrhiza (24.5%), mycorrhiza treatment (23.8%), and the combined treatment of vermicompost with Pseudomonas and mycorrhiza (23.7%), which showed an increase of 10.61, 7.98, and 7.59 percent compared to the control, respectively. The highest safranal concentration was observed in the vermicompost treatment (41%), although there was no significant difference compared with the combined treatment of vermicompost with mycorrhiza (37%) and phosphorus chemical fertilizer (39%). In addition, the use of biofertilizers and their combination increased the amount of picrocrocin in saffron stigma, so that there was no significant difference with phosphorus chemical fertilizer treatment. In general, the results indicate that feeding saffron vermicompost and inoculating it with microorganisms had a significant effect on saffron growth and yield. The use of these fertilizers is an acceptable approach to reduce the overuse of chemical fertilizers while maintaining yield.

Abstract One of the methods to improve production and control flowering in plants is the use of growth regulators such as gibberellic acid. In order to investigate the effect corm priming time of saffron with gibberellic acid (GA3), a factorial experiment was conducted in a randomized complete block design with three replications at the Agricultural Research Station,University of Tehran in 2023. Two planting times (late June, late September) and four levels of gibberellic acid (0, 100, 200, and 400 ppm) were considered as treatments in the form of corm priming. The evaluated traits were the number of buds, time to germination, number of flowers, time to flowering, bud-to-flower conversion ratio, dry weight of stigma, and quality traits of saffron stigma. The results showed that priming saffron corms with 100 ppm gibberellic acid in late June significantly (α=1%) increased the number of flowers, bud-to-flower conversion ratio, fresh and dry weight of stigma, crocin and safranal. However, corm priming in late September with 200 ppm gibberellic acid resulted in a significant increase (α=1%) in the number of buds, number of flowers, stigma length, fresh and dry weight of stigma, and a significant decrease (α=1%) in the time to flowering onset and germination, although in some traits they were in the same statistical group as the 400 ppm level. Overall, the results of this experiment showed that first, corm priming in late June with low levels of gibberellic acid is better, but, corm priming in late September with higher levels is beneficial. Secondly, corms priming in late June and at a level of 100 ppm of the hormone can increase the amount of crocin and safranal and yield traits, while priming corms in late September can reduce the time to flowering and time to germination And will improve flower and corm yield in the first year.

Abstract To evaluate the allelopathic and antifungal effects of saffron (Crocus sativus L.) leaf and corm extracts on the germination and early growth of Peganum harmala and on the mycelial growth of Fusarium nygamai, three independent factorial experiments were conducted using a completely randomized design with three replications. The experiments were conducted in 2021 at the Seed Research Laboratory, Research Greenhouse, and Plant Disease Laboratory of the Faculty of Agriculture at the University of Birjand. In the first experiment (laboratory bioassay), treatments consisted of two saffron plant organs (leaf and corm) and seven extract concentrations (0, 0.0625, 0.125, 0.25, 0.5, 1, and 2% w.v^-1) applied to assess inhibitory effects on the germination parameters of wild rue seeds. The second experiment (greenhouse pot study) employed identical treatments to evaluate seedling emergence and growth characteristics. In the third experiment, the same treatment structure was used to investigate the inhibitory effects of extracts on the mycelial growth of F. nygamai. The results of the interaction between treatments under laboratory conditions showed that the lowest germination percentage, mean germination time, and allometric coefficient were obtained with the 2% concentration of corm extract. The lowest length of radicle and shoot, dry weight of shoot, and root were obtained from the 2% concentration of corm extract. In greenhouse conditions, the 2% corm extract and the 1 and 2% leaf extract treatments resulted in the lowest germination percentage, the longest mean germination time, the lowest germination rate coefficient, and the lowest allometric coefficient. Furthermore, the minimum shoot length, root length, shoot dry weight, and root fresh weight were obtained from the same treatments. The results of the antifungal test showed that the lowest colony diameter on the third and sixth days was observed with the 2% extract, which did not differ significantly from that of the 1% extract. On the ninth day, the lowest colony diameter was obtained from a concentration of 2% corm extract, which had no statistically significant difference with concentrations of 1 and 2% leaf extract. Finally, the results of these experiments showed that the effect of inhibiting germination and growth of wild rue in laboratory conditions was greater in saffron corm extract and in greenhouse conditions in leaf extract, and the antifungal effect of leaf extract was greater. Therefore, based on the results of this study and further research into the fungicidal and allotoxic effects of saffron organ extracts, it is possible to develop natural fungicides and herbicides.

Abstract The shift toward sustainable medicinal plant production underscores the importance of biological inputs. This study evaluated the effects of humic acid application, mycorrhizal inoculation, and two irrigation regimes on reproductive growth and quality of saffron (Crocus sativus L.). The experiment was conducted as a split-split plot based on a randomized complete block design (RCBD) with three replications, where irrigation intervals (20 and 40 days) were the main plot, humic acid (0 and 5 kg.ha⁻¹) was the sub-plot, and mycorrhizal inoculation (noninoculated, Glomus mossea, and G. intraradices) was the sub-sub plot. The studied traits were the number of flowers, flowering rate, flower yield, petal yield, style yield, and stigma yield, as well as stigma quality 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 (20 days) combined with humic acid application and G. mossea inoculation significantly increased fresh flower yield (79.63 g.m⁻²), dry stigma yield (0.88 g.m⁻²), style yield (0.22 g.m²), and petal yield (9.88 g.m ²). Crocin content was highest (274.5, absorbance of 1% aqueous solution at 440 nm) under 40-day irrigation intervals with humic acid and G. mossea inoculation, while safranal (35.80, absorbance at 330 nm) and picrocrocin (124.5, absorbance at 257 nm) improved under 20-day irrigation intervals with humic acid and G. mossea. Conversely, extended irrigation intervals (40 days) without humic acid and without mycorrhizal inoculation resulted in the lowest crocin and safranal content. Overall, the findings demonstrate that combining humic acid with G. mossea inoculation 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 may differ from those of their combined application. On the other hand, the interaction among two or more of these inputs can also vary depending on conditions, including water availability and the type of mycorrhizal species.

Abstract Evaluating and quantifying agricultural ecosystem services in saffron-based agroecosystems is essential for understanding their economic value and informing sustainable management. This study aimed to estimate and monetize multiple ecosystem services and disservices in saffron fields. Researchers collected primary data by using a structured questionnaire with saffron growers from selected counties in Khorasan Razavi and South Khorasan provinces (Mashhad, Torbat-e Jam, Torbat-e Heydarieh, Khalilabad, Bardeskan, Birjand, Zirkouh, and Boshruyeh), resulting in 120 completed questionnaires. The study estimated the value of five saffron ecosystem services—food production, oxygen production, biodiversity, conservation, and the absence of migration—and two disservices —greenhouse gas emissions and phosphorus and nitrogen leakage. Results showed that the total net value of ecosystem services in the studied fields was 39,353.6 US$/hectare per year. Prevention of rural migration, identified as a cultural service, was valued at 24,579.3 US$/hectare per year. Cultural and provisional services and biological diversity made up 62, 43, and 5.8% of the total ecosystem service value in saffron fields. These findings highlight the importance of assessing both ecosystem services and disservices in saffron agroecosystems to guide sustainable management and policy decisions.

Abstract Saffron is a high-value crop of strategic and economic importance in Iran, particularly in semi-arid regions. Its productivity and quality are influenced by complex interactions among agronomic, environmental, and management factors. This study aimed to identify and analyze the key determinants of saffron yield (stigma yield per hectare and per kilogram of fresh flowers) and quality indices (crocin, picrocrocin, and safranal) using a datadriven approach. In 2023, data were collected from 99 saffron farms across eight counties in Razavi Khorasan Province, encompassing 75 variables that recorded climate, soil, management practices, and farmer demographics. Least Absolute Shrinkage and Selection Operator (LASSO) regression with 10-fold cross-validation was applied for variable selection and predictive analysis. Results indicated that stigma yield per hectare was primarily influenced by corm planting rate, organic fertilizer, corm weight, and field area, achieving R² = 0.63 and RMSE = 3.75 kg.ha⁻¹. For stigma yield per kilogram of fresh flowers, phosphorus fertilization, corm weight, and planting density were the strongest positive predictors, with R² = 0.70 and RMSE = 0.69 g.kg⁻¹. Moderate positive effects were observed for organic fertilizer and irrigation frequency, while quadratic effects suggested threshold responses for corm size and irrigation. For quality traits, phosphorus was the dominant positive predictor of crocin (β = 18.3) and picrocrocin (β = 3.97), whereas altitude and foliar spray frequency negatively affected picrocrocin and safranal. The effects of nitrogen and sulfur fertilizers were minor and nonlinear. Simplified models retained predictive accuracy (R² = 0.70), improving practical applicability. These findings highlight the importance of sitespecific phosphorus management, corm quality monitoring, and optimized irrigation for enhancing saffron yield and quality. LASSO regression effectively identified influential variables, supporting precision agriculture and decision-support tools for sustainable saffron production under semi-arid conditions.

Abstract This study evaluates the technical efficiency of saffron farms in Torbat Heydarieh and Zaveh Counties, ‎located on northeastern Iran, using a two-stage double-bootstrap Data Envelopment Analysis (DEA) ‎approach. Cross-sectional data were collected from 108 saffron producers across six districts, and ‎technical efficiency (TE) scores were estimated under variable returns to scale (VRS) with an input-‎oriented DEA model. The bias-corrected double-bootstrap procedure of Simar and Wilson (2007, ‎Algorithm 2) was applied with 1000 replications to ensure consistent inference and robust estimation. ‎Results reveal that the Farrell efficiency estimates tend to overstate farm technical efficiency by ‎approximately 25 percent. I detected significant regional disparities in efficiency scores (χ² = 12.74, p < ‎‎0.05), with the highest mean efficiency observed in Kadkan (0.32) and the lowest in the Central district ‎‎(0.17). The truncated bootstrap regression identified an inverted U-shaped relationship between farm ‎age and efficiency, where efficiency initially increases with farm age but declines beyond a certain ‎point. Experience in saffron cultivation had a strong positive and statistically significant effect on ‎efficiency (p < 0.01), while education level and farmer’s age were not significant predictors. Slack ‎analysis revealed considerable input-specific inefficiencies and spatial heterogeneity in slacks. On ‎average, farms could reduce water use by 706.88 m³/ha, land by 3.04 ha, corm use by ‎528.10‎ kg/ha, and ‎labor by 20 person-days/ha without reducing output.‎

Abstract In order to investigate the effects of planting date and first irrigation date on growth and yield of saffron an experiment under Nasrabad climatic condition of Torbat-e Jam city in 2017 - 2018 was carried out as a split plot based on randomized complete blocks design with three replications. Experimental treatments were six planting dates (22 May, 5 June, 22 June, 6 July, 23 July and 6 August) as main plots and three irrigation times: irrigation after each planting, irrigation on 21 August and irrigation based on custom region on 7 October (control) as sub plots. In this study, number of flowers, flowers fresh weight, stigma fresh and dry weight, crocin, picrocrocin and safranal were measured. Results showed yield and components of yield decreased by delaying in planting date and irrigation after each planting. In the first and second years of the experiment, respectively, the highest number of flowers per m2 (16.41 and 49.35), the highest fresh flower yield (47.60 and 127.73 kg/ha), the highest fresh stigma yield (4.09 and 12.95 kg/ha), and the highest dry stigma yield (714 and 2841 g/ha) were obtained on May 22 planting date with combination with irrigation on August 21. All treatments had no significant effect on crocin content. The maximum content of picrocrocin (111.33 mg/g) and safranal (53.77 mg/g) recorded on 21 August irrigation treatment. Picrocrocin content decreased by delaying in planting date and the highest of picrocrocin was observed on 22 May and 5 June. Based on the results, it was recommended that saffron planting from 22 May until 6 July, no irrigation after planting and irrigation on 21 August are good method for saffron production.

Abstract Water deficit regimes and techniques using moisture-absorbing materials are key approaches to achieving sustainable agriculture goals and conserving water resources in arid and semi-arid regions. To evaluate the effect of superabsorbent polymers on water productivity and the quantitative and qualitative traits of saffron under deficit irrigation conditions, a field experiment was conducted over three growing seasons (2020-2021, 2021-2022, and 2022-2023) in agricultural lands of Ziar, a district of Isfahan, Iran. The experiment was designed as a split-plot within a randomized complete block design (RCBD) with three replications. The main plots included three levels of irrigation (50%, 75%, and 100% of water requirement), while the subplots consisted of various levels of superabsorbent polymer application (0, 50, and 100 kg. ha-1). The results were analyzed at a 95% significance level. The findings revealed that the highest values for leaf number (25 and 34 leaves per plant), dry leaf yield (3845 and 4926 kg. ha-1), fresh flower yield (1559 and 1912 kg. ha-1), dry stigma yield (11.8 and 17.8 kg. ha-1), corm number (278 and 345 per m²), and corm yield (32.1 and 45.1 t. ha-1) were obtained in the 2021-2022 and 2022-2023 growing seasons under 100% irrigation combined with 100 kg. ha-1 of superabsorbent polymer application. Notably, improvements in these crop parameters were significantly greater when superabsorbent polymers were used under water-deficit conditions compared to full irrigation conditions. Furthermore, the highest water productivity was achieved under the 50% irrigation treatment combined with 100 kg. ha-1 of superabsorbent polymer, yielding 0.005 and 0.007 kg. m-3 of water. Additionally, the 75% irrigation treatment along with 100 kg. ha-1 of superabsorbent polymer resulted in the highest concentrations of crocin (13.0% and 12.4%), picrocrocin (6.6% and 5.9%), and safranal (2.6% and 2.4%) during both experimental years. Overall, the results indicated that while the highest quantitative yield of saffron was achieved with full irrigation and the application of superabsorbent polymer, the best outcomes in terms of saffron quality were observed under the 75% irrigation treatment combined with the polymer application. Considering the limited water resources in the studied area and the importance of water productivity, this treatment is recommended as the optimal approach for sustainable saffron production in regions with conditions similar to the experimental site.

Abstract To evaluate the effect of bi-ofertilizers containing element-fixing bacteria on saffron production under drought stress conditions, an experiment was carried out in split plots and a basic RCBD design in two consecutive years (2020-2021 and 2021-2022) in ACECR's research complex for medicinal plants. Experimental treatments included two levels of drought stress (50 and 100% of saffron water requirement) and six levels of fertilizer (control, 100%NPK, 50%NPK, 50%NPK+three biofertilizers, 50%NPK+four biofertilizers, three biofertilizers). Based on the results, the dry weight of the flower, the dry weight of the corolla and stamen, the number of flowers, and the weight of the daughter corms decreased in both years with increasing drought intensity. Also, drought stress in the second year had a more significant effect on reducing these traits. In both years, the use of biofertilizers containing bacteria, along with half of the recommended amount of chemical fertilizers containing nitrogen, phosphorus, and potash (50% NPK + three biofertilizers), led to the achievement of the highest dry weight of stigma, dry weight of flower, dry weight of corola + stamen and number of flowers per unit area. However, the complete removal of chemical fertilizers (three Biofertilizers without chemical fertilizers) had no significant effect on the improving saffron yield. The increase in drought stress severity did not significantly impact the number of corms or the average weight of each corm; however, it did lead to a notable reduction in corm weight. Treatment of simultaneous use of four biofertilizers along with half of the recommended amount of chemical fertilizers containing nitrogen, phosphorus, and potash (50% NPK + four biofertilizers) resulted in the highest corm weight per unit area, achieving a value nearly three times greater than that of the control treatment. These findings suggest that the concurrent application of biological and chemical fertilizers is advisable for fulfilling the nutritional requirements of saffron plants, promoting corm production while minimizing the reliance on chemical fertilizers. In summary, the results of this study indicate that biological fertilizers can effectively substitute a portion of the chemical fertilizers traditionally used in saffron cultivation, regardless of the presence or absence of drought stress.

Abstract This study aimed to explore the agronomic and economic implications of intercropping cumin and saffron in the Ghohestan region of South Khorasan province at a private research farm, under the supervision of the faculty of agriculture, University of Birjand, during the 2022-2023 period. To assess saffron's performance when intercropped with cumin, an experiment was set up based on a randomized complete block design with three replications in a uniform three-year-old saffron field. The experimental treatments involved different densities of cumin cultivation in the saffron field, including 0, 30, 60, and 120 plants per square meter (0, 25, 50, and 100% of its optimal density, respectively). The findings revealed that the LER index exceeded one in all treatment groups. The highest saffron stigma yield, recorded at 0.41 kg/ha, was achieved with an intercropping density of 60 cumin plants per square meter. The highest LER values were 1.94 and 1.92, obtained in the treatments with 30 and 60 cumin plants per square meter, respectively. Additionally, the Relative Value Total (RVT) was above one across all intercropping ratios. The greatest Intercropping Advantage index (IA), recorded at 0.074, was also achieved with the 60 plants per square meter cumin treatment. Consequently, increasing the cumin planting density in saffron fields, particularly at 60 plants per square meter, did not significantly affect saffron yield, leading to a recommendation for farmers in this region to adopt this practice for improved land use and economic benefit.

Abstract As a strategic crop in Iran's economy, saffron is highly vulnerable to climate change. Analyses indicate that extreme events such as frost during flowering periods and prolonged droughts are key factors in reducing saffron yield. This study aims to analyze trends in extreme temperature and precipitation indices and model their impact on saffron yield using multivariate regression. Data on daily low and high temperatures, as well as rainfall from 1990 to 2020, were collected from weather stations in Torbat-e Heydariyeh and Kashmar to calculate extreme climate measures using the ETCCDI method, which was applied using RClimDex software. Saffron yield data was obtained from the Agricultural Jihad Organization. Trend analysis indicated that annual precipitation has had a significant decline. Extreme temperature indices (TNm, TMm, TXm, WSDI) and heavy precipitation indices (R99p at both stations and R95p in Torbat-e Heydariyeh) exhibited significant decreasing trends (p < 0.05). For Kashmar, the multivariate regression model incorporated four extreme indices (R² = 0.70, RMSE = 0.49, NRMSE = 16.4%). Key predictors included ID (β = -0.14, the strongest yield-reducing factor), extreme low temperatures or TNn (β = +0.10), tropical nights (TR20), and consecutive dry days (CDD) negatively impacted yield. For Torbat-e Heydariyeh, the model demonstrated higher accuracy (R² = 0.83, RMSE = 0.43, NRMSE = 15.9%). Significant predictors were TXn (β = +0.18) and frost days or ID (β = -0.12) as the most positive and negative drivers. Overall, temperature variables—particularly nighttime temperatures—dominated yield variability. These findings provide a foundation for climate-smart saffron cultivation planning in similar semi-arid regions. Mitigation strategies should prioritize thermal regulation (e.g., altitude selection, mulching) and water management to offset warming-induced stress.

Abstract Accurate estimation of saffron water demand is essential for sustainable water resource management in saffron-growing regions. This study examines the optimization of the Artificial Neural Network (ANN) model for predicting saffron water demand using the hybrid Coati Optimization Algorithm (COA). The performance of the ANN-COA model was compared with ANN, ANN-GA, ANN-PSO, ANN-MFO, Quadratic Regression (QR), Tree Regression (TR), and Pattern Regression models. Input data included temperature (minimum, maximum, average), wind speed, relative humidity, net radiation, and day of the year. The results showed that under conditions using all climatic parameters, the ANN-COA model achieved an R² of 0.995 and a Mean Squared Error (MSE) of 0.0001 for the Mashhad station, and an R² of 0.973 and MSE of 0.0005 for the Birjand station, indicating acceptable accuracy in predicting saffron water demand. Additionally, under conditions with limited climatic parameters, the ANN-COA model, using maximum temperature, wind speed, and day of the year, exhibited the best performance in predicting saffron water demand. Based on the findings of this research, hybrid neural network models show superior accuracy in estimating saffron water demand with minimal climatic parameters compared to other data mining models.

Abstract Evaluating the response of various saffron ecotypes regarding physiological and biochemical traits, as well as stigma-related characteristics, is crucial for cultivation in specific regions. Therefore, a study was conducted to assess the physiological, biochemical, and stigma-related traits of five saffron ecotypes (Torqroud: EC1, Natanz: EC2, Kashan: EC3, Qaenat: EC4, and Badroud: EC5) in pots under open field conditions at the Islamic Azad University Research Farm in Ardestan in 2022, following a completely randomized design with three replications. Results indicated significant differences in yield, quality, physiological, and biochemical traits among the examined ecotypes. The EC2 ecotype was significantly superior in yield traits such as stigma diameter (2.09 mm), stigma length (2.43 cm), number of flowers (95.40 per m2), fresh flower yield (47.27 g m-2), and dry stigma yield (0.828 g m-2). The levels of safranal, picrocrocin, and crocin in the EC2, EC3, and EC4 ecotypes were significantly higher compared to other ecotypes, with the highest values of these traits observed in EC2 (53.02, 175.1, and 202.6 E_(1 cm)^(1%), respectively). The content of photosynthetic pigments (chlorophyll a, b, and total) was highest in the EC2 ecotype compared to the others. In terms of antioxidant enzyme activity, EC1 and EC4 ecotypes exhibited the highest activity. Correlation results indicated a positive relationship between yield and quality traits. Overall, this study clearly demonstrates that environmental conditions can significantly impact the quality and yield of saffron, aiding in the selection of the best ecotypes for cultivation in different regions. The EC2 ecotype is recommended for cultivation in the studied area after field trials.

Abstract Saffron is one of the most popular and well-known spice and medicinal plant species in the world. Limited information is available regarding the nutritional properties and allocation of phytochemicals in this plant. The aim of this study is to evaluate the impact of different concentrations of forchlorfenuron and potassium nitrate on the accumulation of carbohydrates and starch metabolism in saffron stigmas and corms. This experiment was carried out in a factorial design in a randomized complete block design at the research farm of Zanjan University. The first stage of foliar application was conducted in early February and the second stage in early March. In this study, traits such as soluble carbohydrates and starch content in stigmas and corms, the activity of the enzyme beta-amylase in stigmas and ADP-glucose pyrophosphorylase (AGP) enzyme in corms, stomatal conductance and resistance, photosynthetic rate, sub-stomatal CO₂ concentration, chlorophyll a, b and total chlorophyll, anthocyanins, and flavonoids were measured. Additionally, the percentage of nutritional elements in stigmas and corms including nitrogen and potassium was determined. Based on the results, the interactive effect of forchlorfenuron at 5 mg/L with potassium nitrate at 500 mg/L resulted in increased nitrogen and potassium in the corms, stomatal conductance, photosynthetic rate, sub-stomatal CO₂ concentration, chlorophyll a, total chlorophyll, flavonoids, and soluble carbohydrates in the stigmas. Transpiration rate and anthocyanin levels were not influenced by the treatments. Nearly all treatments, with the highest response observed with forchlorfenuron at 5 mg/L in combination with potassium nitrate at 1000 mg/L, led to an increase in starch content in the corms. The activity of the enzyme ADP-glucose pyrophosphorylase in corms continuously increased with higher levels of CPPU and KNO₃, especially reaching 49.96 µmol/min/g protein with a treatment of 5 mg CPPU and 500 mg KNO₃. This indicates an increase in starch storage in saffron stigmas under these treatments. This study reveals significant insights into the role of CPPU and potassium nitrate on growth, nutrient absorption, carbohydrate metabolism, and allocation of phytochemicals in saffron. Treatment with 5 mg/L CPPU and 500 mg/kg KNO₃ significantly improved all physiological parameters examined. This treatment resulted in increased carbohydrate storage, improved nitrogen and potassium uptake in stigmas and corms, enhanced activity of the enzyme ADP-glucose pyrophosphorylase in corms, and considerable increases in the qualitative characteristics of saffron such as safranal, crocin, and picrocrocin. The results obtained can contribute to improving the weight and quality of saffron corms to increase flower production in field conditions.

Abstract Evaluating the allocation trend of photoassimilates during the saffron growing season can lead to the identification of the key periods of plant growth. It is possible to improve the growth of the corm and ultimately increase the flowering of saffron by applying agricultural management according to the growth period. In this research, the allocation of photoassimilates between different organs of saffron under the influence of the mother corm weight (less than 4, 4-8, and 8-12 g) and the integrated and time-scheduled application of inputs (low-input and high-input), were investigated in a factorial layout based on a randomized complete block design with three replications. The maximum root weight was gained around 20th January (70 days after the first autumn irrigation) and the maximum leaf weight was observed on 29th February, and then it decreased, but after this date, the growth rate of the corm increased and reached its maximum value in the last month of the growing season. In all treatments, most of the mother corm reserves were consumed in the first 100 days after the first autumn irrigation, which coincides with mid-January. The production of replacement corms and their total weight accelerated 140 days after the first autumn irrigation, and its maximum amount (655 No. and 4148 g.m^-2, respectively) was obtained at the end of the growing season in the conditions of planting of big corms + high-input system. The highest mean weight of replacement corms (7.8 g) at the end of the growing season was obtained through planting of large mother corms + low-input system, while by planting small mother corms, the high input system increased the mean replacement corm weight. In all treatments, the highest corm growth rate was observed in the last month of the growing season (approximately 170 days after the first autumn irrigation). The total plant weight was strongly influenced by the weight of the mother corms, with no significant differences observed between the two input application levels. The highest crop growth rate (CGR) occurred in the final month of plant growth, reaching a maximum of 74.3 g.m⁻² day⁻¹ under the combination of large corm planting and a high-input system. The plant's relative growth rate (RGR) increased during the time intervals of 100–140 and 180–200 days after the first autumn irrigation. There was no significant difference between the treatments in terms of the duration of the active period of corm filling, and it was about 45 days. At the end of the growing season, the highest and lowest levels of photoassimilate remobilization (reallocation) from leaves to replacement corms (1016 kg.ha⁻¹ and 220 kg.ha⁻¹, respectively) were observed with the planting of large corms combined with a high-input system and small corms combined with a high-input system. The maximum remobilization efficiency (56.2%) was achieved by planting 4–8 g mother corms and using the high-input system. According to the results of this study, the final month of saffron growth was identified as the most critical period for the corm growth rate.

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.

Abstract  The study was conducted in order to compare the yield of onion, flower, stigma, and some agricultural characteristics of the saffron plant as an alternative crop. This study was carried out as a complete randomized block design in 3 replications in three regions of Aliabad, Naqdeh, Qajlu, Miandoab, and Balanj, Urmia, and in each region, four ecotypes of Korqand, Hoz-sarakh, Jarf, and Shahnabad were cultivated evaluated for 5 years from September 2016. From the second year to the fifth year, flowers were harvested, and the agricultural traits of the ecotypes, including the number of flowers, fresh weight of flowers, dry weight of petals, stamens, and production stigma yield, were measured or recorded. In the sixth year, the yield and the number of corms produced were measured. The results showed that there was a significant difference between the ecotypes. The interaction effect of place in ecotype, year in ecotype, and year in place was also statistically significant. The highest yields of stigmas and flowers were produced in Aliabad Naqdeh region, and among the four saffron ecotypes cultivated, Korqand and Jarf ecotypes had the highest number and weight of flowers, the highest weight of stigmas, the number of corms and the weight of corms in all three regions, respectively. According to the results, the ecotypes of Korqand and Jarf ecotypes are recommended for cultivation in the central and southern parts of West Azerbaijan province.

Abstract Drought stress is one of the most important abiotic stresses that reduces crop production more than any other stress. Micronutrients such as iron and zinc can improve drought stress tolerance in saffron. For this purpose, the present study was conducted in the growth chamber of the College of Science, University of Tehran, in order to investigate the effect of iron and zinc on vegetative characteristics and resistance traits of saffron plant under water stress conditions as a factorial based on a completely randomized design. In this experiment, iron and zinc were investigated at three levels of half concentration of Hoagland, full concentration and twice the concentration of Hoagland solution and at four levels of dryness of 0, 5, 10 and 15% polyethylene glycol 6000 (PEG). The results showed that drought stress reduced fresh and dry root weight (1.36 g and 0.12 g in PEG 15%), root length (2.67 cm in PEG 15%), leaf and root protein content (0.05 and 0.04 mg/g FW in PEG 15%) and oxidizing enzymes (such as root peroxidase (1.04 IU/g protein in PEG10% and in PEG15% (1.09 IU/mg protein), leaf polyphenol oxidase (in PEG5% (0.14, 0.15 IU/mg protein in PEG10% and 0.14 IU/mg protein in PEG15%), leaf catalase (0.63 in PEG5%, 0.59 IU/mg protein in PEG10% and 0.34 IU/mg protein in PEG15%) and root catalase (0.25 IU/mg proein in PEG10% and 0.18 IU/mg protein in PEG15%). The use of iron and zinc in full concentrations and twice the concentration of Hoagland solution improved some qualitative and biochemical properties such as total chlorophyll (full concentration of zinc in PEG15% as much as 4.48 mg/g FW), chlorophyll a (twice the concentration of zinc in PEG5% as much as 2.96 mg/g FW), chlorophyll b (zinc at full concentration in PEG15% as much as 5.04 mg/g w/w) Wet), carotenoids (zinc twice the concentration in PEG10% by 0.73 μg/mg protein), leaf flavonoids (iron twice the concentration of PEG5% by 0.18 μg/g FW), zinc root flavonoid twice the concentration in PEG0 by 0.15 μg/g FW), leaf flavonoids (iron twice the concentration in PEG15% by 0.05 μg/g FW) and flavonols (Leaf flavonols (twice the concentration of iron in PEG15% by 0.05 μg/g FW) and root flavonols (twice the concentration of iron in PEG5% by 0.21 μg/g FW). Finally, treatment with iron and zinc improved the status of some of the measured parameters under drought stress conditions. The use of these concentrations of iron and zinc is recommended to reduce the negative effects of drought in saffron.

Abstract Given that saffron is a bulbous and perennial plant, various environmental factors can significantly influence its growth and development. To investigate the corm and flower characteristics of saffron under the influence of different biofertilizers and irrigation regimes, an experiment was conducted over two agricultural years (2021-2022 and 2022-2023) in the agricultural fields of Ziar city, a suburb of Isfahan. The experiment was designed as split plots in a randomized complete block design with three replications. In this experiment, deficit irrigation at three levels (50%, 75%, and 100%) was considered the main factor, while nitrogen-fixing free-living bacteria (B-N), potassium-solubilizing bacteria (B-K), phosphate-solubilizing bacteria (B-P), their combinations, and a control without fertilizer were considered the sub-factor at eight levels. The results demonstrated that the highest number of corms (415 m-2), corm weight (2360 g. m-2), corm weight without tunics (2304 g. m-2), number of corms weighing 0-4 grams (244 m-2), number of corms weighing 4-8 grams (135 m-2), number of corms weighing 8-12 grams (55.3 m-2), and number of corms weighing more than 12 grams (64.2 m-2) were obtained under the 100% irrigation requirement treatment with the combined NPK biofertilizer. Moreover, the highest dry stigma weight (0.492 g. m-2) and dry style weight (0.122 g. m-2) were achieved in the 100% irrigation requirement treatment with the combined NPK biofertilizer. Overall, the application of biofertilizers improved corm and flower performance characteristics under all three levels of drought stress. However, the positive effects of biofertilizers were more pronounced under stress conditions. Therefore, considering the ongoing water scarcity crisis in the country and the beneficial effects of biofertilizers, it is possible to achieve optimal yields with reduced water consumption.

Abstract The saffron bulb mite (Rhizoglyphus robini Claparède) is considered a serious threat in saffron cultivation areas in Iran. This soil-borne mite reduces the growth and is a cause of the yellowness of saffron plants and eventually destroys the corms. Due to the significance of this strategic product and its medicinal and export aspects, it is impossible to register any synthetic chemical compounds against pests and diseases of this plant in the country. Therefore, finding non-chemical and based on natural substances methods for the control of this pest is necessary. In this research the use of mite-pathogenic fungi is considered a promising approach for controlling this pest. To isolate and identify these fungi, soil samples were collected from saffron farms in 32 regions of Torbat-Heydarieh County in Khorasan Razavi province in 2022 and 2023. Overall, 55 fungal isolates related to eight genera were obtained and among them, 26 isolates could colonize the mites. The potent isolates that killed mites and caused at least 50 percent mortality after ten days were compared statistically. The results showed that on the 10th day, the effect of Metarhizium sp. isolate M-Kh and Cordyceps sp. isolate Co-TZ on mite mortality was 100 percent which was higher than other fungi, but, their difference with some isolates belonged to Beauveria sp. was insignificant (P<0.05). The mite colonization percentage of M-Kh isolate was 100 percent and significantly higher than other fungi (P<0.05). Cladosporium sp., Aspergillus spp., Penicillium spp., Fusarium spp., and Mucor spp. also caused the death of mites, but their effect was insignificant. Based on available information, this is the first report of the pathogenicity of the mentioned fungal genes against the saffron bulb mite in Iran. According to the results, these selected fungi can be used as biological control agents to protect saffron corms against mites.

Abstract Saffron corm rot caused by the bacterium Burkholderia gladioli pv. gladioli (Bgg), is an important disease affecting saffron cultivation. This study aimed to evaluate the effect of different doses of sodium bicarbonate and three copper-based compounds (copper oxychloride, Bordeaux and Nordox) on the population of Bgg isolates, in vitro. Additionally, the sensitivity of the Bgg isolates to 21 antibiotics was investigated. Two weeks after inoculation, the symptoms of the disease appeared as dry rot and brown lesions around the inoculated area. Varying degrees of virulence were observed among the Bgg isolates, with the Bg16 inducing the most severe symptoms. The Minimum inhibitory concentrations (MICs) were determined as copper oxychloride 3.5/1000, Bordeaux and sodium bicarbonate 12%, and Nordox 1.5/1000. The Bgg isolates were sensitive to nine antibiotics. The largest inhibitory zone diameters observed around trimethoprim sulfamethoxazole, nalidixic acid, gentamicin, and amikacin discs. One week after cultivation, the copper compounds decreased the bacterial population compared to the control, but no significant difference was observed between them in the second week. The most effective treatments in reducing the Bgg population were copper oxychloride at 2/1000 and 3/1000, Bordeaux at 8% and 10%, and Nordox at 1/1000 and 1.5/1000. The efficacy of the identified effective treatments will be further evaluated under field conditions.