Nanotechnology has great potential, as it can enhance the quality of life through its applications in various fields like agriculture and the food system. Around the world it has become the future of any nation. But we must be very careful with any new technology to be introduced regarding its possible unforeseen related risks that may come through its positive potential. However, it is also critical for the future of a nation to produce a trained future workforce in nanotechnology. In this process, to inform the public at large about its advantages is the first step; it will result in a tremendous increase in interest and new applications in all the domains will be discovered. With this idea, the present review has been written. There is great potential in nanoscience and technology in the provision of state-of-the-art solutions for various challenges faced by agriculture and society today and in the future. Climate change, urbanization, sustainable use of natural resources and environmental issues like runoff and accumulation of pesticides and fertilizers are the hot issues for today's agriculture. This paper reviews some of the potential applications of nanotechnology in the field of agriculture and recommends many strategies for the advancement of scientific and technological knowledge currently being examined.

Nanotechnology opens a large scope of novel applications in the fields of plant nutrition needed to meet the future demands of the growing population because nanoparticles (NPs) have unique physicochemical properties, i.e. high surface area, high reactivity, tunable pore size, and particle morphology. Management of optimum nutrients for sustainable crop production is a priority-based area of research in agriculture. In this regard, nanonutrition has proved to be the most interesting area of research and concerns with the provision of nano-sized nutrients for sustainable crop production. Using this technology, we can increase the efficiency of micro- as well as macronutrients of plants. In the literature, various NPs and nanomaterials (NMs) have been successfully used for better nutrition of crop plants compared to the conventional fertilizers. This review summarizes these NPs and NMs into macro-, micro-, and nanocarrier-based fertilizers and plant-growth-enhancing NPs with unclear mechanisms, describing their role in improving growth and yield of crops, concentration/rate of application, particle size, mechanism of action if known, toxic effects if any, and research gaps in the present research. Moreover, future research directions for achieving sustainable agriculture are also discussed in the appropriate section and at the end in the concluding remarks section.

Drought is one of the major abiotic stresses to sustainable agriculture and global food security. The present study was conducted to evaluate the integrated effect of algal biochar (BC) and plant growth-promoting rhizobacteria (PGPR) on growth and physiology of maize under deficit irrigations. A pot experiment with different combinations of algal BC and PGPR under three deficit irrigations [field capacity (FC), 75% FC and 50% FC] was performed using maize as test crop. There were three controls without application of algal BC and PGPR under each water deficit irrigation. Both algal BC and plant growth-promoting rhizobacterial inoculation mitigated negative effects of deficit irrigations on maize performance, especially when applied in combined form. Under 50% FC, combined application of algal BC and PGPR significantly increased fresh and dry weights of shoot and root and root length by 2.76, 5.94, 3.24, 13.82, and 4.06 times compared to control, respectively. In case of physiological and nutrient uptake parameters, the same treatment caused the maximum increase in comparison to control. Post-harvest soil analysis also showed a positive treatment effect compared to their respective control. The combined application of algal BC and PGPR could be an effective strategy to improve growth and physiology of maize under deficit irrigations.

Bio-activated organic fertilizers (BOZ) were produced by enriching the zinc oxide (ZnO)-orange peel waste composite with Zn solubilizing bacteria (ZSB: Bacillus sp. AZ6) in various formulations (BOZ1 (9:1), BOZ2 (8:2), BOZ3 (7:3) and BOZ4 (6:4)). The produced BOZs, along with ZnO, ZnSO4, ZSB were applied to maize crop (Zea mays L.) under field conditions in two different cropping season and the growth, yield, physiology, plant Zn contents and quality of maize were investigated. Results revealed significant variation in the aforementioned parameters with the applied amendments. The BOZ4 performed outclass by exhibiting the highest plant growth, yield, physiology, Zn contents, and quality. On average, an increase of 53%, 49%, 19%, 22%, 10%, 4%, and 30% in plant height was noticed with BOZ4 application over control, ZnO, ZnSO4, BOZ1, BOZ2, BOZ3, and ZSB, respectively. BOZ4 enhanced the dry shoot-biomass 46% than control. Likewise, the photosynthetic rate, transpiration rate, stomatal conductance, chlorophyll contents, carotenoids, and carbonic anhydrase activity were increased by 47%, 42%, 45%, 57%, 17%, and 44%, respectively, under BOZ4 over control in both cropping seasons. However, BOZ4 reduced the electrolyte leakage by 38% as compared to control in both cropping seasons. BOZ4 increased the Zn contents of grain and shoot by 46% and 52%, respectively, while reduced the phytate contents by 73% as compared to control. Application of BOZ4 revealed highest average fat (4.79%), crude protein (12.86%), dry matter (92.03%), fiber (2.87%), gluten (11.925%) and mineral (1.53%) contents, as compared to control. In general, the impact of cropping seasons on maize growth, yield, physiology, Zn contents, and quality were non-significant (with few exceptions). Thus, bio-activation of ZnO with ZSB could serve as an efficient and economical strategy for boosting up the growth, yield, physiological, and quality parameters of maize under field conditions.