Screening sorghum for tolerance to excess manganese in solution culture

Abstract

This study was conducted to define traits to screen sorghum (Sorghum bicolor L. Moench) genotypes for tolerance to excess Mn. Visual Mn toxicity symptoms, net and total root lengths, shoot and root dry matter yields, and shoot and root Mn concentrations were determined for plants grown in nutrient solutions (pH 4.5) at different levels of Mn (0, 3, 6, 9 and 12 mM above the initial 18 ~tM) to assess plant responses to excess Mn. Dry matter yields showed greatest variability among genotypes, and was an effective trait to evaluate sorghum for tolerance to excess Mn. Reductions in dry matter yields did not occur until Mn levels were above 3 mM. Levels of Mn between 3 and 6 mM could effectively be used to screen sorghum for genotypic differences to excess Mn. Manganese levels above 6 mM were too severe to allow good genotypic differentiation. Of genotypes tested, NB9040 and Wheatland showed good tolerance and SC283 and ICA-Nataima were sensitive to excess Mn.

Sorghum genotypic differences in tolerance to excess manganese

“…Information on level of Mn and trait to best assess sorghum genotypes for differences to excess Mn in solution culture has recently been reported (Mgema and Clark, 1994). This study showed that 3.0 and 6.0 mM Mn in solution resulted in good differences among eight sorghum genotypes in response to excess Mn, but 9.0 and 12.0 mM Mn were too high.…”