Effects of biological fertilizers on physiological traits and bioactive compounds in saffron (Crocus sativus L.)

Relatively few studies have explored the impact of biofertilizers on the qualitative and quantitative yield of saffron despite its global agricultural and medical importance. This study aimed to evaluate the physiological and phytochemical responses of saffron to potassium (K), phosphorus (P), and iron-zinc (Fe-Zn) biofertilizers over 2 consecutive years (2022-2023). The treatments included single and combined applications of K, P, and Fe-Zn biofertilizers containing active bacterial inoculum, along with a control group, resulting in a total of eight treatments. Biofertilizers were applied at a rate of 0.5 L per hectare by fertigation in mid-February. Flowering began in mid-November in both 2022 and 2023, lasting approximately 3 weeks, during which data were collected.

The highest flower count (3.5 times greater than the control group), longest flowering duration (2.4 times longer than the control group), greatest stigma dry weight (3.2 times higher than the control group), and highest flowering rate (1.2 times greater than the control group) were recorded in the second year application of the K + Fe-Zn treatment. The K + Fe-Zn treatment also enhanced quality traits significantly, including total phenolic content (1.11 g kg^-1; an increase of 1.1 times relative to the control), anthocyanin (977 mg kg^-1, an increase of 8.4 times), crocin (126.9 g kg^-1, an increase of 1.2 times), picrocrocin (59.8 g kg^-1, an increase of 1.2 times), and safranal (1.8 g kg^-1, an increase of 3.3 times).

Overall, the 2 year application of K + Fe-Zn solubilizing bacteria as biofertilizer improved both the qualitative and quantitative traits of saffron markedly, underscoring its potential importance in sustainable saffron cultivation in mineral-fortified soils. © 2024 Society of Chemical Industry.