Reduction of Drought Stress Effects on Saffron (Crocus sativus L.) using Phytohormones

Abstract

The effects of global warming and climate changes on plant growth in arid and semiarid regions have prompted the implementation of crop improvement strategies to mitigate these adverse impacts. One of these strategies involves the application of foliar treatments. A study including two irrigation levels with 70% and 50% field capacity, representing mild and severe drought stresses, respectively, and five spraying treatments were conducted. The spraying treatments included no spraying (control), zinc sulfate (ZnSO4: 3/1000), salicylic acid (SA: 40 mg/l), methyl jasmonate (MeJA: 2 mg/l), and auxin (IAA: 1/5 mg/l). It was observed that the levels of chlorophylls a and b in the leaves increased in response to drought stress. Furthermore, an escalation in the severity of drought stress resulted in heightened levels of secondary metabolites (crocin, picrocrocin, and safranal). Conversely, the dry weight of daughter corms decreased due to drought stress. Additionally, the proline, soluble sugars contents, and nitrogen, potassium, and zinc absorption were increased in MeJA and IAA-treated daughter corms under mild and severe drought stress conditions. On the other hand, phosphorous uptake decreased significantly under severe drought stress compared to mild stress conditions. Likewise, the application of MeJA and IAA significantly increased stigma and petal yields, as well as the content of secondary metabolites in saffron. Moreover, MeJA and IAA applications enhanced water use efficiency under both mild and severe drought stress conditions, highlighting their potential to reinforce the non-enzymatic defense system, increase daughter corm dry weight and nutrient uptake, improve saffron quality and quantity, and alleviate the adverse effects of drought stress in saffron plants however, further research is warranted to comprehensively understand these effects