Breeding soybeans for improved adaptation to iron deficiency chlorosis

Abstract

Major objectives of the Northrup King Co. soybean breeding program include high yield potential, resistance to lodging and shattering, good emergence, adequate protein and oil levels, and resistance to diseases and pests, as well as resistance to iron deficiency chlorosis (IDC). Any cultivar released from the program must have a favorable combination of those characteristics which are important in the area of adaptation.

The Northrup King soybean research group began actively breeding for resistance to IDC in 1977. Breeding procedures have included screening of advanced experimental lines, crossing resistant x resistant parents, and mass‐selection in populations derived from resistant x susceptible crosses. Performance of two recently released cultivars selected from resistant x susceptible crosses indicate that it is possible to combine high yield levels from one cultivar with IDC resistance from another. Several strains selected from crosses involving highly resistant parents have been evaluated and some show promise for release. However, susceptibility to Phytophthora root rot (Phytophthora megasperma f. sp. glycinea) has been a problem with many of these strains.

Key words:

• Breeding procedures
• breeding objectives
• selection of parents
• mass‐selection
• screening techniques