Effects of foliar spray of nano-micronutrient and growth regulators on safflower (Carthamus tinctorius L.) performance

Nanoparticles have unique properties and providing nutrients in the form of nanoparticles may increase the effectiveness of chemical fertilizers. The current study aimed to streamline the relevance between soil nutrient management and the efficiency of foliar spray by growth regulators or nano micronutrients. A field trial was performed to evaluate the impacts of different fertilizers (control, 20 t ha⁻¹ farmyard manure: FYM, 200 kg ha⁻¹ NPK fertilizer) and foliar spray (distilled water as control, choline, salicylic acid, chitosan, and nano Zn+Fe) on growth and seed yield component of safflower. The results showed that most of the assessed agronomic traits showed different responses to fertilizers and foliar sprays. The utilization of FYM and chemical fertilizers increased the plant height (by 5.38% and 7.26%) over the control. Foliar spray of choline and nano Zn+Fe increased the number of primary branches under inorganic by 49% and 21% and their improved number of primary branches under FYM applied condition by 54% and 39%. The largest lateral growth of the canopy and the highest number of capitula was obtained by applying FYM and foliar spray of chitosan and nano Zn+Fe and these foliar treatments increased the lateral growth of the canopy by 23% and 18% over control. The highest seed number in the secondary capitula was obtained by utilization of NPK fertilizer and foliar spray of chitosan and choline. The highest seed yield was related to plants grown by NPK fertilizer and sprayed with chitosan, choline, or nano Zn+Fe (1145, 1231, and 985 Kg ha⁻¹, respectively). Overall, the positive effect of Zn+Fe nanoparticles is strongly dependent on soil conditions, and the best efficiency of nanoparticles was observed in soils that have previously received suitable organic and chemical fertilizers.