Response of Yield, Antioxidant Enzymes Activities, and Fatty Acids in Peanut (Arachis hypogaea L.) to Bio-fertilizers and Amino Acids in Different Irrigation Regimes

Bio-fertilizers (BF) and amino acids (AA) improve plant growth by activating antioxidant enzymes and establishing a favorable metabolic environment to maintain physiological balance and drought stress mitigation. This experiment aimed to assess the influence of some BF and AA on peanuts (Arachis hypogaea L.) under drought stress. It was conducted during 2018–2019 as a split-split plot based on a randomized complete blocks design with three replications in the experimental field of the Agricultural and Natural Resources Research and Education Center of Guilan province, Rasht, Iran. Three irrigation regimes including irrigation after 75 (IR75), 100 (IR100), and 125 (IR125) mm evaporation from class A evaporation pan, four levels of BF including no application of bio-fertilizers as control (Z0), Arbuscular mycorrhiza (AM), Azospirillum brasilense (AB), Pseudomonas fluorescens (SF) and four levels of AA including no application of AA as control (Z0), Aminol-Forte (AF), Humi-Forte (HF) and Pro-Amin (PA) comprised experimental treatments as main plot, sub-plot and sub-sub plot, respectively. Peanut seed yield (SY) decreased under intensive drought stress. In 2018 and 2019, peanut SY increased by 43.34 and 38.08% in IR75 compared to control, under the interaction of AB×HF and SF×HF, respectively. The interaction of AB and HF increased antioxidant enzymes and improved SY under drought stress, which can be considered an innovation. Hence, the application of AB and HF could be recommended to enhance peanut SY under similar climatic conditions.