Role of some nanomaterials in management of nutrients stress in crop plants

Zinc, iron, and silicon nanoparticles (NPs) are widely used in plant system. As their mineral base is a relevant constituent of the earth's crust, they are are commonly found in nature; indeed, Zn and Fe are considered essential nutrients. The Zn, Fe, and Si NPs effects on the plant are known, but its role in a nutrient acquisition under salinity and drought stress is less known. Thus, this chapter aimed to analyze critically the role of Zn, Fe, and Si NPs on crop plant nutrient acquisition under salinity and drought stress to comprehend their physiological and biochemical regulations. The specific information is scarce; however, we found tangential studies in several crop plants like cereals, legumes, oilseeds, and vegetables, where the NPs could play a relevant role in plant nutrition under abiotic stress allowing alleviate it and give a better plant response. Most of the authors suggest that smaller NPs increase the efficiency to counter the adverse effects. Moreover, direct exposition of NPs to soil or via fertilizer was preferable rather than foliar spraying methods. Zinc, iron, and silicon NPs affect the nutrient acquisition, trending to increase some macronutrient and micronutrients concentration in plant tissue; also, the relevant cations (K, Ca, and Mg) are increased, and Na is reduced, which is traduced in an increased of (K, Ca, and Mg)/Na ratio under salinity. The mechanisms underlying are not fully elucidated because several factors interact as NPs size and doses, and its electrical and chemical properties, mainly when are soil-applied. More studies are necessary to discover the primary mechanisms involved in the effect of NPs on nutrient stress, which could explain some observations and validate its use on the productive scale for contributing to satisfying the increasing food needs of the human population.