Slow-release Zn application through Zn-chitosan nanoparticles in wheat to intensify source activity and sink strength.

Abstract

Source activity and sink strength are important aspects to measure growth and yield in wheat. Despite zinc s extended functions in the amendment of plant metabolic activities, critical research findings are missing on mapping the elusive interplays of slow-release zinc (Zn) application from nanoparticles (NPs) in crop plants. The present study reports that slow-releasing Zn application through Zn-chitosan NPs bestows myriad effects on source activity and sink strength in wheat plants. Herein, effects of foliar application of Zn-chitosan NPs (0.04-0.16%; w/v) at booting stage of wheat crop were evaluated to quantify the source sink potential compared to ZnSO4. Zn-chitosan NPs endowed elevated source activity by up-regulating cellular redox homeostasis by improving the antioxidant status, cellular stability and higher photosynthesis. Cognately, in the field experiment, NPs (0.08-0.16%, w/v) significantly spurred sink strength by up-regulating starch biosynthesis enzymes viz. sucrose synthase (SUS), invertase (INV), ADP-glucose pyrophosphorylase (AGPase), soluble starch synthase (SSS) and accumulated more starch in developing wheat grains. Concomitantly, higher spike lengths without awns, significantly higher number of grains/spike, test weight (24% more than ZnSO4 treatment), yield (21% more than ZnSO4 treatment), biological yield and harvest index quantified the higher sink size to further validate the better sink strength in slow-release Zn application via chitosan NPs.