Under What Conditions Can Rain-Fed Saffron Be Cultivated in Semi-Arid Regions?

Saffron could be produced under rain-fed conditions, but the required conditions are not well known. To determine these conditions, crop growth models can be used. The modified SYEM model for rain-fed saffron was calibrated and validated. Then, it was used to predict the rain-fed saffron production in different saffron production areas. Comparison of the measured and predicted values of crop parameters showed that in modeling the saffron crop, it is essential to consider the age of the field; the density of corm at the beginning of each growing season should be included in the model. The saffron yield (SY) values were predicted by the validated model for important saffron cultivation areas in Iran under rain-fed conditions with the use of plastic mulch (PM) and pre-flowering irrigation (PFI) in 3 years with high, low, and mean rainfall depth. In general, in rain-fed conditions, soil texture, time, depth, and frequency of rainfall are very important in saffron growth and SY. The use of PM and PFI increased the SY by 1.5 and 3.0 times, respectively, compared to not using them. The use of PM and in-furrow planting, in areas with light soil texture and low annual rainfall (< 200 mm), has a greater effect on increasing the SY. In areas with medium to heavy soil texture and high annual rainfall, the use of PM increased the SY at rainfall depths below 300 mm. In general, the use of PFI in all areas with any annual rainfall depth is necessary due to softening the soil surface at the beginning of the growing season after the summer dormancy period. Depending on the soil texture, the PFI value should raise the soil water content in the saffron root zone to the soil field capacity.