---

The aim of this research was to study the effect of iron oxide nanoparticles (FeO NPs) on the growth, differentiation, anatomy, and physiology of pepper (Capsicum annuum L.) on the basis of a completely randomized design in vitro condition. Seedlings were cultured in MS medium containing four concentrations of FeO NPs (0, 1, 10, and 20 mgl^-1). Also, the effect of the different concentrations of FeO NPs on callus formation under two various hormone conditions (0.5mgl^-1 2,4D+0.5 mgl^-1 BAP or 0.5 mgl^-1 BAP+1 mgl^-1 Kin) were assessed. The results showed that the application of FeO NPs significantly increased biomass accumulation in both roots and shoots. Moreover, FeO NPs enhanced the concentrations of photosynthesis pigments (chllrophyll a, chlorophyll b, and carotenoids). The presence of FeO NPs in culture medium affected callus formation in a hormone-dependent manner. Different concentration of FeO NPs induced the callus formation under 2, 4-D and BAP treatments. However, it did not significantly increase callus formation under the kinitin and 2,4-D. The findings of this research indicated that the application of FeO NPs at optimized doses may improve plant production, especially in vitro condition.

---

The Moldavian dragonhead (Dracocephalum moldavica L., Lamiaceae) is an annual medicinal plant with beneficial nutritional sources that plays important roles in human and animal feed. Nanoparticles and cold atmospheric plasma increase biochemical compounds in plants. In this study, the effects of copper nanoparticles and cold atmospheric plasma on biochemical indices of the medicinal plant Dracocephalum moldavica were investigated. Moldavian dragonhead plants were subjected to four doses of copper nanoparticles (0, 25, 50 and 75 mgl^-1) and cold atmospheric plasma at three durations (zero, 20 and 30 s). The results showed that cold atmospheric plasma significantly increases the essential oil percentage, while it decreases the amount of flavonoid content and activity of catalase and peroxidase enzymes. Cold atmospheric plasma (20 s) showed significant positive impact on essential oil content, while different time duration (20 and 30 s) did not show a significant impact on other traits. Lower doses of copper nanoparticles (25 and 50 mgl^-1) showed positive impacts on measured traits, while 75 mgl^-1 dose negatively affected the measured traits and functioned as a heavy metal. The cold atmospheric plasma and copper nanoparticles interactions indicated that cold atmospheric plasma had an incremental effect on the improvement of measured traits and increased the effect of copper nanoparticles. In conclusion, the results showed that copper nanoparticles with 25 mgl^-1 dose along with cold atmospheric plasma with 20 s duration had significant positive effects on the improvement of biochemical indices of Dracocephalum moldavica.
 
 

---

Selenium, a non-essential element for plants, is essential for animals as well as human beings. Although the role of selenium in plants is yet to be properly understood, previous researches have shown that this element can affect plant growth and metabolism. In this study, the effect of foliar application of selenium nanoparticles (0, 5, 10, and 20 mg/L) and sodium selenate (0, 5, 10, and 20 mg/L) on the physiological and biochemical responses of bell pepper (Capsicum anumm L.) was investigated. The potential changes in various growth and biochemical indices were evaluated in response to the treatments. According to the results, selenium treatments at concentrations of 10 and 20 mg/L reduced the biomass accumulation in both roots and shoots. These treatments also increased the content of hydrogen peroxide and malondialdehyde. The foliar application of selenium led to the increase of the concentrations of soluble phenols, proline and thiols. The activity of antioxidant enzymes including catalase, peroxidase, ascorbate peroxidase, and polyphenol oxidase were increased in response to the selenium treatments. The protease activity displayed a similar upward trend following the selenium treatments.