Effects of Weak Magnetic Fields on Plant Chemical Composition and Its Ecological Implications

Abstract

The exposure of plants to weak magnetic fields (MFs) of various intensities and for different times is increasingly adopted to sustainably enhance plant growth in plant-based applications such as modern agriculture, phytoremediation and biogas production. However, little is known about the effects of MF exposure on plant chemical composition, and in turn on related ecosystem processes, such as the transfer of potentially toxic elements along food chains and the decomposition of organic matter. To fill this gap, the present research, through the study of the chemical composition of four edible crops (leaves of lettuce, parsley and basil, and fruits of tomato) differently exposed to weak MFs (75 Hz; 1.5 mT), aimed at evaluating the overall effects of the exposure on ecosystem processes. In particular, several essential (B, C, Ca, Cu, K, Fe, Mg, Mn, Mo, N, Ni, P, S, Zn), beneficial (Co, Na, Se, Si) and non-useful (Al, As, Ba, Cd, Cr, Li, Pb, Sr, Ti, V) elements, together with chemical compounds and derived parameters (soluble sugars, starch, chlorophylls, flavonoids, anthocyanins, nitrogen balance index), indicators of plant metabolism and health, and litter decomposability traits (C/N, C/P), were analyzed. Notwithstanding the expected variations in the observed effects among species and MF exposure conditions, the obtained results highlight a general decrease in most of the studied parameters (with the exception of those related to litter decomposability), attributable to a lower absorption/accumulation of the studied chemical elements and to a reduced synthesis of metabolites. The largest average reduction was observed for the non-useful elements, which outweighs the reduction in essential and beneficial elements and provides for an important MFinduced effect, considering their toxic, persistent and biomagnificable characteristics. Similarly, the induced increases in C/N and C/P ratios indicate the production of litter more recalcitrant to the decomposition process, suggesting that weak MF treatments may be useful to enhance soil C storage and reduce CO2 emissions.