Copper deficiency or toxicity in agricultural soil circumscribes a plants growth and physiology, hampering photochemical and biochemical networks within the system. So far, copper sulfate (CS) has been used widely despite its toxic effect. To get around this long-standing problem, copper nanoparticles (CuNPs) have been synthesized, characterized, and tested on mung bean plants along with commercially available salt CS, to observe morphological abnormalities enforced if any. CuNPs enhanced photosynthetic activity by modulating fluorescence emission, photophosphorylation, electron transport chain (ETC), and carbon assimilatory pathway under controlled laboratory conditions, as revealed from biochemical and biophysical studies on treated isolated mung bean chloroplast. CuNPs at the recommended dose worked better than CS in plants in terms of basic morphology, pigment contents, and antioxidative activities. CuNPs showed elevated nitrogen assimilation compared to CS. At higher doses CS was found to be toxic to the plant system, whereas CuNP did not impart any toxicity to the system including morphological and/or physiological alterations. This newly synthesized polymer-encapsulated CuNPs can be utilized as nutritional amendment to balance the nutritional disparity enforced by copper imbalance. © 2015 American Chemical Society.