Effect of Deoxycholate Capped Silver Nanoparticles in Seed Dormancy Breaking of Withania somnifera

Plant population growth and persistence are strongly influenced by germination and recruitment, which can be dramatically affected by seed dormancy. Generally, pre-sowing weakens physical dormancy and initiates seed germination, but Withania somnifera seeds are an exception in this case. The basic objective of this study was to develop an alternate protocol to break the physical dormancy in W. somnifera seeds using deoxycholic acid capped silver nanoparticles (AgNPs). For this, high surface reactive silver nanoparticles were synthesized using sodium deoxycholic acid (NaDC) as a reducing agent (NaDC–AgNPs). Seed sets were concurrently soaked with NaDC–AgNPs (20 ppm), and sodium deoxycholate (20 ppm), gibberellic acid (GA₃; 20 ppm) and water as control for different durations (20, 30, 60 and 90 min). Germination was initiated under tissue culture conditions. NaDC–AgNPs-treated seeds showed uniform germination quality of the highest order and increased total germination percentage (TGP) in short time; it was about 93.3% on the fifth day of culture. GA₃ and NaDC-treated seeds showed TGP of 36.6 and 63.33 at the 15th day of culture respectively. NaDC–AgNPs-treated seedlings showed enhanced growth by fresh weight (31.33 mg), radicle length (16.88 mm) and cotyledon length (8.21 mm) compared to control. SEM analysis of seeds showed clear evidence of scarification effects over NaDC–AgNPs-treated seeds. Thus NaDC–AgNPs initiated early germination response in Withania seeds by breaking the physical dormancy with the highest TGP.