Synergistic effect of nickel and melatonin on drought tolerance in pea (pisum sativum)

Introduction: The intensification of drought events due to climate change threatens global food security. Pea (Pisum sativum) is a key legume for sustainable agriculture, as it fixes nitrogen, improves soil fertility, and has high nutritional value. However, it is highly sensitive to water stress. Nickel (Ni) is an essential micronutrient in nitrogen metabolism, while melatonin (MEL) regulates oxidative stress. As such, the aim of this work was to evaluate the isolated and combined effects of Ni and MEL on the physiological, biochemical, and productive responses of pea plants under drought stress. Results: The combined application of Ni and MEL in drought-stressed plants promoted: Increased aerial and root biomass (+27%) and nodule number (+27%), indicating greater nitrogen fixation efficiency. Improved protein content in roots, leaves, and seeds and higher number of pods per plant (+33%) and grain biomass (+21%). Reduced chlorophyll degradation (+15% SPAD), H₂O₂ concentration (-45%) and lipid peroxidation (-38% MDA), suggesting lower oxidative stress. Conclusions: Ni and melatonin synergy improves pea nutrition, strengthens antioxidant capacity, and maintains cellular integrity, leading to higher productivity under drought stress. This approach may enhance legume resilience to climate change, promoting sustainable agriculture.