Effects of foliar application of salicylic acid and nanosilicon on the yield and physiological traits of maize (Zea mays.) in heavy metal contaminated fields

Industrialization and destructive human activities have led to a rapid spread of heavy elements contamination in soil. The purpose of this study was to investigate the effect of silicon and salicylic acid on yield and physiological traits of corn in Rahimi and Molavi farms (contaminated with heavy metals and located near lead and zinc factors in Zanjan) in 2020, by using a factorial design based on randomized complete blocks. Factors included spraying salicylic acid at zero, 600, 1200, and 1800 µM, and spraying nanosilicon at zero, 600, 1200 and 1800 mM. Based on the results of soil analysis, lead, zinc, and cadmium concentrations in both fields were higher than the allowable limit and this heavy metal contamination was more severe in Rahimi field. Heavy metal contamination reduced plant height, grain yield and yield components, biological yield, chlorophyll content, and proline levels. The highest grain yield and grain weight were obtained with 1800 µM salicylic acid and 1200 mM nanosilicon treatments, and the lowest with the control treatment (without salicylic acid or nanosilicon). The highest chlorophyll content was obtained from 1800 µM salicylic acid treatment on Molavi's farm and the maximum amount of chlorophyll was observed in 1800 mM nanosilicon treatment. Overall, the treatments improved the yield, chlorophyll content, and relative water content of corn leaves. It is recommended to spray 1800 µM salicylic acid and 1200 mM nanosilicon on the corn fields in this area to increase the stress tolerance under heavy metal conditions.