Comparison of Iron and Zinc Nanoparticles with Different Sizes and Bulk Forms on Seed Yield and Its Components in Flaxseed (Linum usitatissimum L.) under Late-Season Water Deficit

Flaxseed is an important crop that is used extensively for medicine, nutrition, and industry. Then, this research aims to investigate the effect of foliar spraying of bulk and nanoparticle forms of iron and zinc with different particle sizes on yield and its related traits of flaxseed under post-anthesis water deficit. To this end, a split-plot factorial experiment based on randomized complete blocks design in three replications was used at Razi University, Kermanshah, Iran, in two crop years (2019-2021). The experiment comprised two moisture regimes - optimal irrigation and post-anthesis water deficit, applied in the main plots. Different fertilizers (bulk and nanoparticles with varying particle sizes) and fertilizer concentrations (0, 300, and 600 mg l-1) were tested in the subplot. The results showed that under optimal moisture conditions, the highest grain and biomass yield was in the foliar treatments of iron nanoparticles 20-30 nm and 600 mg l-1 and zinc nanoparticles 10-30 nm and 300 mg l-1, with 2448 and 8432 kg ha-1, respectively and the lowest amount was obtained in the control treatment with 2028 and 7599 kg ha-1. Under post-anthesis water deficit environment, zinc nanoparticles 10-30 nm and 300 mg l-1 caused a 35% increase in grain yield compared to the control treatment (997 kg ha-1). Also, the highest oil percentage and yield were obtained in iron nanoparticles 20-30 nm and 600 mg l-1 with 35.25% and 866 kg ha-1, respectively. In general, the efficiency of iron and zinc nanoparticle fertilizers with different particle sizes was significantly higher than that of iron and zinc bulk forms and control treatment (without fertilization). Nanoparticle fertilizers significantly reduced the adverse effects of late-season water deficit on grain, oil, and biomass yield.