Evaluation of Metallic Nanoparticles and Plant Growth Regulators Affecting Catharanthus roseus L. Performance under Water-Deficit Stress

This study aimed to evaluate the effects of nanoparticle fertilizers and plant growth regulator (PGR) treatments on Catharanthus roseus (L.) plants under water-deficit stress. Plant growth and yield were evaluated in two consecutive years (2018-2019 and 2019-2020). This experiment was performed as a split factorial plot arranged in a randomized complete block design (RCBD) with three replications. The main factor was irrigation at three levels (full irrigation, mild, and severe water-deficit stress). The subfactors included priming with PGRs (not priming, auxin, gibberellic acid, and cytokinin) and foliar application of nanoparticles (water, nano Zn particles, nano Mg particles, and nano Zn particles + nano Mg particles). The results showed that water-deficit stress decreased total chlorophyll content, plant height, number of flowers, and shoot dry weight. However, plants primed with PGRs had higher plant height, lateral branches, and shoot dry weights than the control. The highest vinblastine (0.0091%) and agmatine content (0.667%) occurred in response to severe water-deficit stress and ZnO (1 mg L-1) + MgO (0.5 mg L-1). Moreover, stem diameter and lateral branches had the highest value without priming with plant growth regulators but with ZnO application (1 mg L-1) + MgO (0.5 mg L-1). In contrast, priming with gibberellic acid and foliar application of ZnO (1 mg L-1) + MgO (0.5 mg L-1) increased the agmatine content. The current study suggested nanoparticles and PGRs can enhance Catharanthus roseus tolerance to water-deficit conditions.

Evaluation of Metallic Nanoparticles and Plant Growth Regulators Affecting Catharanthus roseus L. Performance under Water-Deficit Stress Keywords:

Antioxidant activity , Biofertilizers , Osmotic regulation , plant growth regulators , secondary metabolites