Interaction of mycorrhizal fungi and putrescine on physiological characteristics, growth and yield of Lallemantia iberica under Pb stress conditions

In the last two decades, soil contamination with heavy metals has increased in many agricultural areas. Therefore, in order to investigate the interaction of mycorrhiza and putrescine on physiological characteristics, lead content, and yield of Lallemantia iberica under lead (Pb) stress, a factorial experiment was conducted in a randomized complete block design in the Research Greenhouse of the Faculty of Agriculture, University of Zanjan in 2018. Experiment consisted of Pb in four levels (0, 300, 600, and 900 mg Pb/kg soil) from the source of Pb(NO3)2, mycorrhiza at three levels (no inoculation, Funneliformis mosseae, and Rhizophagus intraradices), and putrescine in three levels (0, 0.5, and 1 mM). The results showed that among the Pb levels, 900 mg/kg caused the greatest decrease in the greenness index, relative water content, height, plant dry weight, root length, and grain yield, and increased electrolyte leakage, plant Pb concentration, colonization, and proline content. At all Pb levels, both fungi, especially F. mosseae, increased greenness index, relative water content, height, plant dry weight, root length, and yield, and decreased plant Pb concentration. At all Pb levels, the concentration of 0.5 mM putrescine decreased electrolyte leakage and plant Pb concentration, and increased proline content, plant dry weight, yield, and colonization. In all traits, putrescine had a synergistic effect with F. mosseae, but only 0.5 mM putrescine had a synergistic effect with R. intraradices. In general, the interaction of 0.5 mM putrescine with F. mosseae had an additive effect on plant growth, especially under Pb stress conditions.