PLANT nutrition is an important branch of plant biology, which deals with different nutrients, and their uptake by cultivated plants as well as their biochemical functions in plants. This science is also involving the production of safe and healthy food depending on the famous rule “the right 4R Nutrient Stewardship to improve nutrient use efficiency". Several methodologies have been used in plant nutrition research including pot, hydroponic or soilless, micro-farm and field studies, as well as in vitro or plant tissue culture. These studies have focused on many aspects (i.e., physiological, biochemical, anatomical and molecular scales). The molecular plant nutrition has become a crucial issue in different case studies concerning agricultural production particularly under stressful conditions. Molecular plant nutrition research has gained a new dimension in the era of nanotechnology especially under plant nano-nutrition. Several open questions still need to be answered such as what are the possible applications of nanotechnology in molecular plant nutrition? To what extent nano-nutrients can be used in molecular plant nutrition studies and which criteria should be followed in this usage?