The effect of gamma radiation on some growth and phytochemical indices of saffron (Crocus sativus)

In recent years, the use of saffron spice is increasing due to its medicinal properties and effective components. In addition to increasing crop production, increasing the quantity and quality of secondary metabolites is considered one of the most important objectives of plant breeding programs. On the other hand, the saffron plant has low genetic diversity due to the nature of vegetative propagation and induction of variation through mutagenesis is a suitable tool to achieve the desired diversity. Gamma radiation is one of the most widely used physical mutagens in plant breeding programs. In order to investigate the effect of gamma-ray on some growth and phytochemical indices of saffron plants, an experiment was conducted in an unbalanced complete randomized design with three treatments (Control, 15 and 18 Gy) at Yazd University. In this experiment, 15 and 18 Gy doses of gamma irradiation (Co60) were applied at Karaj Nuclear Agricultural Research Institute to induce mutations on collected saffron corms from Qaen, South Khorasan in August 2017. In this study, picrocrocin, safranal and crocin were measured in a 1% aqueous solution at 254, 330 and 440 nm wavelengths, respectively. Based on the results of this experiment, the effect of irradiation on picrocrocin and crocin was significant (P <0.001) and the observed amounts of these compounds (93.77 and 263.02) at the dose of 15 Gy were significantly higher than 18 Gy (92.34 and 262.73), while in terms of safranal content, the difference between radiation levels was not significant. Leaf area index and harvest index were also significant and showed the highest amount of these two indices at 15 Gy dose (3.06 and 0.14). In this study, although gamma radiation treatment could not significantly change the number of daughter corms between different levels of radiation and control, a significant reduction in relative chlorophyll content and an average weight of corms were observed compared to the control (without radiation). In general, the results of this study showed that in phytochemical traits as well as harvest index and leaf area, 15 Gy had a significant advantage over plants without radiation, but at higher levels of gamma radiation, probably due to degradation of genetic content and its effect on some biochemical parameters, 18 Gy plants failed to show acceptable results.