Breeding for tolerance of nutrient imbalances and constraints to growth in acid, alkaline and saline soils

Abstract

Useful genetic variation apparently exists in all major field crops for tolerance to nutritional imbalances and constraints to plant growth in problem soils of the United States. Inheritance of tolerance to excess aluminum, iron deficiency or salinity can be simple or relatively complex. Sources of tolerance often are available in improved cultivars rather than only in poorly adapted or agronomically unsatisfactory exotics. Up to now, few varieties have been bred specifically to solve mineral stress problems in the U.S., although plant breeding work of this type is beginning to increase in amount. Reasons for the low level of effort seem to be 1) relatively small percentages of U.S. farmland are as yet proven to have major mineral stress problems; 2) reliable and convenient field selection techniques are few, and laboratory selection techniques may not predict field performance; 3) tests for the presumed positive correlations of yield advantage in the field with phenotypic tolerance to specific mineral stresses have rarely been attempted. In absence of such tests plant breeders may be reluctant to dilute their breeding programs with additional selection criteria.

Key words:

• Mineral nutrition
• genetics
• corn
• wheat
• soybeans
• sorghum