Calcium l-aspartate nanoparticles modify the root ultrastructure and improve plant yield in Brassica napus L.

Abstract

Calcium (Ca) is an indispensable nutrient in plant development. Nanoparticles (NPs) are widely used in agricultural production, among which calcium L-aspartate nanoparticles (Ca(L-asp)-NPs), as a new type of Ca fertilizer, have been proven to benefit plant root improvement and stress tolerance. However, the effect of Ca(L-asp)-NPs on the plant root ultrastructure and yield is still not well known. Therefore, in this study, we examined the influence of Ca(L-asp)-NPs on the cellular structure, yield factors, and root nutrients in rapeseed roots. For this purpose, two different experiments were set up: a short-term hydroponic experiment with three treatments: –Ca, no Ca application; NPS-100, 100 mg L⁻¹ Ca(L-asp)-NPs; and Ca-100, 100 mg L⁻¹ Ca(NO₃)₂·4H₂O and a long-term pot experiment with four treatments –Ca, no Ca application; NPS-100, 100 mg kg⁻¹ Ca(L-asp)-NPs; NPS-200, 200 mg kg⁻¹ Ca(L-asp)-NPs; and Ca(NO₃)₂, 130 mg kg⁻¹ Ca(NO₃)₂·4H₂O. The results suggested that the application of Ca(L-asp)-NPs had well-organized intracellular cortical thin-walled cells in the root cross-section structure and had increased the diameter of the root system and thickness of the cortex. Moreover, Ca(L-asp)-NPs further improved plant traits, yield-related factors, and the Ca fertilizer utilization rate. In addition, 200 mg kg⁻¹ Ca(L-asp)-NPs increased the uptake of Ca, Mg, and B contents by the root system while decreasing the uptake of Fe, Mn, and Cu elements. Taken together, the application of Ca(L-asp)-NPs positively impacted the root cellular structure and rapeseed yield. This study provides a solid foundation for considering Ca(L-asp)-NPs as a nano fertilizer for soil application aimed at enhancing.