agronomy Review Some Emerging Opportunities of Nanotechnology Development for Soilless and Microgreen Farming Farhatun Najat Maluin 1 , Mohd Zobir Hussein 1, * , Nik Nor Liyana Nik Ibrahim 2 , Aimrun Wayayok 3 and Norhayati Hashim 4   Citation: Maluin, F.N.; Hussein, M.Z.; Nik Ibrahim, N.N.L.; Wayayok, A.; Hashim, N. Some Emerging Opportunities of Nanotechnology Development for Soilless and Microgreen Farming. Agronomy 2021, 11, 1213. https://doi.org/10.3390/ agronomy11061213 Academic Editor: Elena Maestri Received: 16 May 2021 Accepted: 8 June 2021 Published: 15 June 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Institute of Advanced Technology, Universiti Putra Malaysia, Serdang 43400, Malaysia; farhatunnajat@yahoo.com 2 Department of Chemical and Environmental Engineering, Universiti Putra Malaysia, Serdang 43400, Malaysia; niknorliyana@upm.edu.my 3 Department of Biological and Agricultural Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang 43400, Malaysia; aimrun@upm.edu.my 4 Nanotechnology Research Centre, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, Tanjung Malim 35900, Malaysia; norhayati.hashim@fsmt.upsi.edu.my * Correspondence: mzobir@upm.edu.my; Tel.: +60-3-9769-8092 Abstract: Global food demand has increased in tandem with the world’s growing population, prompting calls for a new sustainable agricultural method. The scarcity of fertile soil and the world’s agricultural land have also become major concerns. Soilless and microgreen farming combined with nanotechnology may provide a revolutionary solution as well as a more sustainable and productive alternative to conventional farming. In this review, we look at the potential of nanotechnology in soilless and microgreen farming. The available but limited nanotechnology approaches in soilless farming include: (1) Nutrients nanoparticles to minimize nutrient losses and improve nutrient uptake and bioavailability in crops; (2) nano-sensing to provide real-time detection of p H, temperature, as well as quantifying the amount of the nutrient, allowing desired conditions control; and (3) incorporation of nanoparticles to improve the quality of substrate culture as crop cultivation growing medium. Meanwhile, potential nanotechnology applications in soilless and microgreen farming include: (1) Plant trait improvement against environmental disease and stress through nanomaterial application; (2) plant nanobionics to alter or improve the function of the plant tissue or organelle; and (3) extending the shelf life of microgreens by impregnating nanoparticles on the packaging or other preservation method. Keywords: agricultural nanotechnology; sustainable agriculture; soilless farming; microgreen farm- ing; nutrient solution; substrate culture 1. Introduction According to the United Nation (UN) Food and Agriculture Organization (FAO), as of 2018, the world’s agricultural land area covered approximately 36% (4.80 billion ha) of the world’s land surface (13.4 billion ha) [1]. Over a decade, the area was reported to have decreased by 0.4% (4.82 billion ha). The top five countries with the most agricultural land area are the USSR, China, Australia, the United States of America, and Brazil, with 0.55 billion ha (11%), 0.47 billion ha (10%), 0.45 billion ha (9%), 0.42 billion ha (9%), and 0.21 billion ha (4%), respectively [2]. Furthermore, although Malaysia has only 0.86 million hectares of agricultural land, it contributed significantly to world economical crops; oil palm and rubber [3]. The United Nations, on the other hand, predicts that the world’s population will reach 8.5 billion by 2030, 9.7 billion by 2050, and 11.2 billion by 2100 [4]. The increased demand for food caused by the world’s growing population has resulted in a decrease in global agricultural land area per capita over time. Another issue to consider is soil health and fertility, which is the foundation of conventional crop cultivation. Climate change, Agronomy 2021, 11, 1213. https://doi.org/10.3390/agronomy11061213 https://www.mdpi.com/journal/agronomy