Effects of silicon on mineral composition of sorghum grown with excess manganese1

Abstract

Silicon can help alleviate Mn toxicity in some plants. Growth chamber studies were conducted to assess the effect of Si on growth and mineral element composition in sorghum. [Sorghum bicolor (L.) Moench] grown in nutrient solutions with excess Mn. Treatments were all combinations of 18, 1800, 3600, and 7200 uM Mn and 0, 890, 1780, and 3560 uM Si using two genotypes. High Mn levels decreased dry matter yields which were partially overcome by the addition of Si, especially at the 1800 and 3600 uM Mn levels. Silicon had no deleterious effects on plant growth at the levels used. Increased levels of solution Mn decreased shoot concentrations of Si, K, Ca, Mg, Zn, and Cu; increased shoot concentrations of Mn and P; decreased root concentrations of K and Mg; and increased root concentrations of Mn, Si, P, Fe, Zn, and Cu. Total uptake of mineral elements by shoots and roots decreased in plants grown with high Mn because of decreased plant growth. Increasing Si levels in solution decreased shoot concentrations of all elements except Si and Zn; decreased root concentrations of S, K, and Mg; and increased shoot and root contents of Si. Silicon partially alleviated Mn toxicity effects in sorghum if Mn was not added at extremely high levels.