Impact of the Maternal Environment On Root Traits in Common Bean (Phaseolus vulgaris).

Low soil phosphorus and drought are primary constraints to crop production in low input agricultural systems, and a threat to food security in many developing nations.  We have identified many root traits that are potentially beneficial for phosphorus acquisition and drought tolerance in common bean (Phaseolus vulgaris).  The utility of these traits is usually tested using seed from a well-watered and high-nutrient maternal environment.  However, many farmers in developing nations plant seed from the previous year’s crop, which is often grown in low phosphorus and/or drought conditions.  It is therefore important to understand how progeny from a low phosphorus or drought maternal environment perform under a stressed environment similar to the mother plants.  We hypothesize that a low phosphorus or soil moisture maternal environment results in progeny with enhanced root traits relevant to phosphorus or soil moisture availability.  Results show that progeny from a drought maternal environment had less seed mass, fewer basal roots at the seedling stage, and steeper adventitious root angles at flowering relative to progeny from a well-watered maternal environment.  Differences in seed mass and basal root number are likely a result of poor maternal provisioning by drought stressed maternal plants, whereas steeper adventitious root angles may be an environmental maternal effect that aids water acquisition from deeper soil in drought conditions.