**1. Introduction**

Nanomaterials (NMs) have attracted great interest especially in the field of agriculture that enhanced productivity of crops with lesser cost and waste [1, 2]. NMs offer sustainable effectiveness in the field of agriculture including protection and production of crops [3]. The significant advancement and development of the newer agricultural technologies is sturdily required because of continuously increasing food requirements globally [4]. The global food production must be increased around 70–100% by 2050 to achieve the demand of growing population [5, 6]. In this context, the agriculture promoted from various innovative

technologies such as hybrid species, synthesis chemicals, and biotechnological developments [7]. However, continuous production of agricultural crops might be one of the great challenges due to the lack of nutrients/changes in climates. To overcome such issues related with the loss of production or improvement in the yield of crops, farmers continuously used agrochemicals. Nonetheless, excessive use of these agrochemicals leads to deterioration of soil, degradation of agro-ecosystems, and environmental problems [8, 9]. In this context, NMs have a technological advancement, might be transformed and allied sectors that provides newer agricultural tools for the management of stresses (biotic and abiotic), detection of diseases, improved nutrients absorption ability, and translocation ability. On the other hand, NMs might help to understand agricultural biology as well as interaction of nanomaterials with plants, thereby enhancing the nutritional value as well as productivity of the crops. However, the exact role of NMs in agriculture still remains a concern.

Numerous NMs including carbon-based nanomaterials (single-walled carbon nanotubes (SW-CNTs), multi-walled carbon nanotubes (MW-CNTs) [10, 11], carbon nanofibers (CNFs), graphene and fullerenes [12–15], metal and its oxidebased nanomaterials [16–18], magnetized iron (Fe) nanoparticles [19], aluminum oxide (Al2O3) [20], copper (Cu) [21], gold (Au) [22, 23], silver (Ag) [24, 25], silica (Si) [26], zinc (Zn) nanoparticles and zinc oxide (ZnO) [27–29], titanium dioxide (TiO2) [30], and cerium oxide (Ce2O3) [31], etc.) and bio-composite nanomaterials have been developed. These NMs are efficiently used in the field of agriculture for production and protection of crops [32–35]. However, phytotoxicity, degradation of soil, large-scale production, agglomeration, and effective delivery system still remain a concern. On the other hand, CNFs have the potential ability to deliver micronutrients in plants and the release of micronutrients (Cu/Zn nanoparticles) in a controlled manner. However, CNFs also required polymeric delivery system for real applications [34]. In this context, polymeric nanocomposite has emerged as one of the most promising tools for the delivery of micronutrients and agrochemicals in the plant system [36].

Several polymers such as polyvinyl alcohol (PVA), chitosan, polyvinyl-pyrrolidone (PVP), starch, hyaluronic acid (HA), poly(lactic-co-glycolic acid) (PLGA), poly-lactic acid (PLA), etc. have been used as a carrier for delivery system for various biological applications due to their high biocompatibility, biodegradability, nontoxicity, cost-effectiveness, and excellent film forming ability [37–39]. Various processes such as cross-linking, emulsion formation, and self-assembly have been used for the synthesis of polymeric nanocomposite that facilitate controlled release of agrochemical/micronutrients within the plants. The encapsulation of nanomaterials by using polymeric matrix also aided advantages to enhance effectiveness of the nanomaterials, decreasing cellular toxicity and environmental contaminations [40]. On the other hand, smart polymeric materials and delivery system have the potential ability to deliver the genes/biomolecules/micronutrients within the plants and also protect viruses and pathogens [41, 42]. This book chapter focuses on the various nanomaterials and polymeric composite that augment the plant growth and interaction of nanomaterials with plants, genes/biomolecules/micronutrient delivery and discuss the advancement of genetic engineering by using nanomaterials.
