Investigation of the role of silicon (Si) in alleviating cadmium (Cd) stress in sorghum plant (Sorghum bicolor L.)

This study was conducted as a pot experiment to investigate the predicted mitigating effects of silicon (Si) treatment on sorghum under cadmium (Cd) stress. The experiment was established in 4 replications with 4 Si doses (0, 100, 200 and 300 mg kg-1) and 3 Cd doses (0, 10 and 20 mg kg-1) according to the factorial design in randomised plots. Master BMR sorghum variety was used in the study. The plants were harvested after 90 days and the concentrations of Cd, Si, Fe, Mn and Zn in plant organs, forage quality and morphological characteristics of sorghum were investigated. As a result of Cd*Si interaction, Cd, Fe and Zn concentrations in roots, stems, leaves and panicles, Si concentration in leaves, Mn concentration in roots and stems, P content in stems and leaves, K content in leaves and panicles, Ca content in panicles, Mg content in stems and panicles, ADF (Acid Detergent Fibre) content in stems, NDF (Neutral Detergent Fibre) content in leaves, CA (Crude Ash) content in stems and leaves, dry stem and dry panicle weights were found significant at p<0,01 level was found to be significant. Cadmium accumulated more in roots than in other organs of sorghum; root>stem>leaf= panicle. Silicon application caused an increase in Si content in tissues, but leaves and especially panicles accumulated more Si than roots and stems. The treatments (Cd*Si) caused a decrease in Fe, Mn and Zn content in roots, Ca and Mg content in stems and leaves. Again, the treatments (Cd*Si) caused an increase in ADF, NDF and crude ash content in stems and leaves and a decrease in crude protein content in leaves, but did not affect CP (crude protein) content in panicles. Silicon treatment increased dry leaf, dry panicle and total plant weight. As a result, in the role of Si treatment in alleviating Cd stress in sorghum plants, Cd10Si200 treatment reduced the Cd concentration in the root (38%), Cd10Si300 treatment reduced the Cd concentration in the stem (28.9%), leaves (30.9%) and panicles (86.6%). At the applied dose of 20 mg kg-1 Cd, it is understood that 3 different Si doses were not effective in alleviating Cd accumulation in the plant. In Cd translocation to panicles, 300 mg kg-1 Si treatment in the presence of 10 mg kg-1 Cd was found to have a strong potential to inhibit Cd translocation. In contaminated areas (<10 mg kg-1) with similar characteristics to the soil used in this study, 300 mg kg-1 silicon is thought to be promising in preventing Cd translocation.