Field Phenotyping of Traits Associated with Drought Tolerance in Dry Bean (Phaseolus vulgaris L).

Dry bean (Phaseolus vulgaris L) is the world’s most important food legume.  Drought is the major cause of yield reductions in this crop.  Michigan is the second largest producer of dry beans in the US, and over 90% of the dry bean acreage planted in the state is grown under rainfed conditions in the Great Lakes watershed.  The objective of this study was to develop field screening methods and identify useful traits in breeding for drought tolerance.  A diversity panel of 96 Mesoamerican varieties was planted in 2011 at the Montcalm Research Center in Lakeview, Michigan.  The plots received a total of 202 mm of rainfall from planting (6/15) to harvest (10/6). This was well below the 30-year average precipitation (430 mm) for the area in this same time period.  Drought stress was observed particularly during a 2-week period during the flowering and early pod filling stages.  The materials included in the trial showed a range of responses in adaptation to drought stress in terms of yield and root architecture. Among the traits measured, higher taproot diameter showed good promise as a root architecture trait associated with drought stress tolerance.