Effects of TiO2 nanoparticles and water-deficit stress on morpho-physiological characteristics of dragonhead (Dracocephalum moldavica L.) plants

Abstract

Water-deficit stress is the most important environmental factors limiting plant growth, and production. Nano-titanium dioxide (nano anataseTiO 2 ) can have various profound effects on the crop physiological, biochemical and morphological characteristics. In the present research, the influences of different concentrations ofTiO 2 nanoparticles (NPs) (0, 10 and 40 ppm) and water-deficit stress on Dragonhead (Dracocephalum moldavica L.) were investigated in a factorial experiment based on randomized complete block design with three replications. Results showed that under normal irrigation, foliar application of 10 ppm TiO 2 NPs increased plant shoot dry mass and essential oils content. Under water-deficit stress condition, plants treated with 10 ppm TiO 2 NPs had more proline and much less H 2 O 2 and malondialdehyde content as compared to untreated plants. Therefore, it can be concluded that proper concentration of TiO 2 NPs probably can be used as an exogenous stimuli for improvement of shoot growth and essential oil content in plants. Furthermore, water-deficit stress-induced damages such as oxidative stress and membrane damage can be ameliorated by foliar application of TiO 2 NPs at appropriate concentrations. Sušni stres je eden izmed najpomembnejših okoljskih dejavnikov, ki omejujejo rast in produktivnost rastlin. Uporaba nano delcev titanovega dioksida (TiO 2 nano anataza) ima lahko velike učinke na fiziološke, biokemične in morfološke lastnosti gojenih rastlin. V tej raziskavi je bil v naključnem faktorskem bločnem poskusu preučevan vpliv različnih koncentracij nano delcev TiO 2 (0, 10 in 40 ppm) in sušnega stresa na moldavsko kačjeglavko (Dracocephalum moldavica L.) v treh ponovitvah. Rezultati so pokazali, da sta se suha masa in vsebnost eteričnih olj povečali pri normalnem namakanju in listnem dodajanju 10 ppm TiO 2 nano delcev. V razmerah sušnega stresa so vsebovale rastline, ki so bile tretirane z 10 ppm TiO 2 več prolina in mnogo manj H 2 O 2 in malonildialdehida v primerjavi z netretiranimi rastlinami. Na osnovi tega bi lahko zaključili, da bi z uporabo primerne koncentracije nano delcev TiO 2 kot zunanjega stimulanta, lahko izboljšali rast poganjkov in vsebnost eteričnih olj pri tej rastlini. Poškodbe kot sta oksidativni stres in poškodovanost membran, ki nastanejo zaradi sušnega stresa, bi lahko ublažili s foliarno aplikacijo primerne koncentracije nanodelcev TiO 2 .

Ameliorative effects of TiO2 nanoparticles and sodium nitroprusside on seed germination and seedling growth of wheat under PEG-stimulated drought stress

“…It seems that TiO 2 NPs may regulate plant growth and play a role similar to plant hormones such as cytokinin and gibberellin as indicated by ability to induce plant cell division and cellular development (Sauret-Güeto et al, 2012). TiO 2 NPs may loosen cell wall and induce cell extension and growth of plant under drought stress (Mohammadi et al, 2016). TiO 2 NPs may also act as a fertilizer and enhance biomass accumulation by stimulating plant metabolic activities (Raliya et al, 2015).…”

Nano titanium dioxide and nitric oxide alleviate salt induced changes in seedling growth, physiological and photosynthesis attributes of barley

“…It was proved earlier, in the presence of n-TiO 2 , CO 2 assimilation and plant photosynthesis were boosted by over expression of rubisco activase (Yamori et al, 2012). In addition, n-TiO 2 attributed to its photo catalytic property can hydrolyse water into oxygen, protons and electrons, in which the produced proton and electron go into an electron transfer chain of plants in the light reaction stage, therefore, enhancing the speed of photosynthesis (Mingyu et al, 2007). In other words, n-TiO 2 can increase the plant photosynthesis through improving the first photosystem light energy that is absorbed by chloroplast membrane and transferred to the second photosystem.…”

Nanoparticles and Nanomaterials as Plant Biostimulants

“…The release of Ti 2+ , which could be beneficial for the plants, seems to be a mechanism that contributes less to the response considering that TiO2 is a poorly soluble element in water [77]. The NPs of TiO2 have been applied as promoters of antioxidant activity and increased tolerance to different stresses: cold [78], heat [79], drought [75,[80][81][82], NaCl [83], and UV [84], in concentrations ranging from 5 to 2500 mg L -1 in plants of different species. Senescent seeds were treated with concentrations from 2500 to even 40000 mg L -1 , with the best results at 2500 mg L -1 .…”

“…However, a constant in all the works was that the positive responses to stress were achieved with the lowest concentrations of TiO2. Figure 5 represents the results obtained on dragonhead and wheat plants by [80] and [75], respectively. It shows the response to low concentrations for the biomass variables of the plant, which constitute the physiological summary of Responses such as those presented in Figure 5, when not referring to essential elements, are considered as hormesis [11] and are characteristic of biostimulants that, according to their agricultural definition [3] induce greater growth without providing nutrients to the plants.…”

“…In "Y" axis the zero number represents the control treatment, a positive value represents a positive effect of the NPs, and a negative value represents an adverse effect on the specified variable. The superscript indicates the reference: dragonhead plants 1[80], and wheat plants 2[75].…”