**1. Introduction**

Population of the globe is rising and is predicted to reach almost 9.6 billion by the year 2050. Sustained growth of 70–100% in global agricultural and food production is essential to feed the growing population [1]. The area under cultivation may shrink over time due to the increasing nonagricultural uses of the land and urbanization, making it difficult to increase agricultural production [2]. Plants are constantly exposed to environmental changes during their life cycle. Deteriorating soil health conditions inevitably have a detrimental impact on plant development and productivity [3]. Billions

of dollars worth of crops are being destroyed each year due to abiotic stresses, such as salinity and drought. Prior to the advent of efficient selection techniques, conventional breeding was used to maintain agricultural productivity, but its effectiveness was constrained by the diversity of stress tolerance traits [2]. Determining innovative solutions to reduce abiotic stress challenges and maintain food security is therefore urgently required under these deteriorating environmental conditions [1] as most promising approach currently available is nanotechnology.

To improve abiotic stress tolerance in agricultural biosystems, Eric Drexler initially coined the term "Nanotechnology" [4]. It deals with the study of nanostructures that possess diverse physicochemical properties and biochemical activities that are dependent on their surface-to-volume ratio [5]. Different physical, chemical, and biological processes can be used to manufacture nanoparticles (NPs), and they can interact with plants in a variety of ways [6]. Crop plants readily absorb NPs, which can enter the cells and play crucial roles in metabolic and growth processes [7]. There is a surge in the use of nanobiotechnology tools in agricultural production that has the potential to boost plant metabolism since NPs promote plant growth, development, and yield to withstand environmental stresses [8]. Additionally, it has been observed that NPs promote the activity of a range of antioxidant enzymes, including catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) [9]. Extensive research revealed that NPs are crucial for plants dealing with abiotic stress conditions [10].

Nanobiotechnology will improve plant functions that will help them cope with environmental challenges [11]. Therefore, this technology is strongly encouraged due to the rising global food demand as well as the potential for positive effects on the economy and ecology [12]. Despite its extraordinary potential in the enhancement of agricultural productivity and improvement in abiotic stress tolerance, the wider application of nanotechnology at the field level is limited in agriculture. In this review article, updates on the positive effects of nanotechnology for the improvement of abiotic stresses in crops have been discussed in detail.
