Objective: This study aimed to assess the efficiency of zinc oxid (ZnO) nanoparticles in mitigating drought stress effects in comparison with bulk ZnO, and to examine the influence of different priming durations on chickpea seed germination under drought conditions.
Method: A three-factorial experiment based on a completely randomized design was conducted with four replications on germination and seedling growth characteristics of chickpea cultivar Kasra. The factors included: 1) seed priming at 5 levels (priming with zinc oxide in the form of nanoparticles 1-100 and 40-60 nm, priming with bulk zinc oxide, hydropriming and no prime), 2) priming duration at 3 levels (6, 12 and 24 hours) and 3) drought stress levels at 4 levels (no stress, -2, -4 and -8 bar using polyethylene glycol 6000).
Results: The results showed that drought stress had a significant effect on all measured variables. Although priming with nanoparticles and bulk zinc oxide performed better than hydropriming; in comparison with bulk zinc oxide priming and nanopriming, nanopriming with a diameter of 1 to 100 nm showed better efficiency. Increasing the drought stress intensity led to a significant rise in the number of abnormal seedlings. Priming especially with zinc oxide (nano and bulk), modulated the drought stress effects in non-stressed conditions and mild to moderate stresses (-2 to -4 bar). However, under severe stress (-8 bar), drought stress damage was not compensated by priming. The results also showed that increasing the priming time had a significant effect on seedling length, germination rate and longitudinal index of seedling vigor. However, increasing the duration from 12 to 24 did not have a significant effect on this increasing trend.
Conclusions: Rapid and optimal germination plays a crucial role in the formation of a reliable crop with excellent yield. Zinc oxide nanoparticles significantly enhance germination, biochemical activities, and seedling growth of chickpea, however, determining the optimal dosage and application method is critical to maximize benefits while avoiding potential toxicity associated with excessive nanoparticle use.
Highlights
- Seed priming with zinc oxide nanoparticles (1–100 nm in diameter) was more effective than using bulk zinc oxide or nanoparticles sized 40–60 nm.
- Under no-stress and mild to moderate drought stress conditions (-2 to -4 bar), priming — particularly with zinc oxide (both nano and bulk forms) — alleviated drought-induced damage.
- Drought stress up to -2 bar did not significantly affect the germination percentage of chickpea seeds compared to the non-primed control.
