Silicon Nanoparticles Mediated In vitro Flowering and Study of Pollen Viability in Vitex negundo L.

Vitexnegundo L. (Lamiaceae) is an aromatic species used to cure several illnesses worldwide. The plant is a panacea of herbal formulations with several of its metabolites exhibiting significant pharmacological properties. The present study is an attempt to find the impact of silicon nanoparticles (SiNPs) on inducing invitro flowering in V.negundo. The floral morphology of invitro and invivo plants was evaluated using standard light microscopy techniques. SiNPs were tested at concentrations ranging from 50 mg L⁻¹ to 300 mg L⁻¹ by supplementation in the optimized shoot proliferation medium (Murashige and Skoog’s medium + 0.5 mg L⁻¹ 6- benzylaminopurine + 0.25 mg L⁻¹ indole-3 acetic acid). The morphometric evaluation indicated 100 mg L⁻¹ SiNP promoted flower bud induction within 2 weeks of the culture of shoots. The floral buds thus formed indicated the presence of distinct calyx, corolla, androecium, and gynoecium. A maximum of 28 flowers were found born on inflorescences by the 8th week of culture. The flowers remained pedicellate, pale purple, bisexual, and zygomorphic. The calyces were greenish-purple, pale-purple corolla, and didynamous-dithecous anthers. The ovary was globose, superior, and the style was linear with a short unequally bifid stigma. The stereomicroscopic analysis of floral morphology revealed that the flowers developed invitro were almost similar to the mother plant except that the size was smaller. The pollens were viable, and the seed set occurred on pollination under invitro conditions. To date, there is no published scientific report on the impact of SiNPs on invitro flower induction in V.negundo and the comparative floral and pollen morphology. The present study confirms that the application of SiNPs could induce year-round invitro flowering, and significantly improve invitro rooting and acclimatization response of V.negundo plantlets.