Screening for sorghum genotypic differences to iron deficiency

Abstract

Sorghum [Sorghum bicolor (L.) Moench] generally is susceptible to iron (Fe) deficiency. Rapid, economical screening methods are essential to screen germplasm in a relatively short time so that genotypes with greater ability to grow on soils with low Fe availability can be developed. Different nutrient solutions were tested to determine which treatments were best suited for screening sorghum genotype tolerance to Fe deficiency conditions. Iron deficiencies were induced by growing seedlings in nutrient solutions with higher than normal levels of phosphorus (P); added calcium carbonate (CaCO₃); nitrate (NO^‐ ₃ ammonium (NH⁺ ₄), and (NO^‐+ ₃ NH⁺ ₄,) as sources of nitrogen (N); and in Fe deficient, calcareous soils in controlled environmental chambers.

Regardless of the screening method, sorghum genotypes differed in their response to Fe deficiency conditions. Larger differences in Fe deficiency were noted among genotypes when NO^‐ ₃ or high P were used. Differences in dry matter yields were greater when the genotypes were grown on soils with low available Fe than when grown in nutrient solutions. Conditions that gave the widest differences in Fe deficiency responses under nutrient culture were 10‐day‐old plants treated with NO^‐ ₃ or with 0.39 mM P. Nearly 100 seedlings could be grown in the same container with limited solution (7 liters). Many genotypes grown in Fe deficient soils did not respond the same as they did in nutrient solutions.

Key words:

• Mineral nutrition
• Nutrient solutions
• Sorghum bicolor (L) Moench
• Iron efficiency
• Iron deficiency
• Improving sorghum for iron deficiency