Comparison of Phytophthora Tolerance between Rps1c and Rps1k Isolines in Soybean.

Phytophthora is a disease in soybeans associated with wet soil conditions commonly occurring on heavy, poorly-drained or compacted soils.  The optimum temperature for infection is 60-80°F and the severity of loss depends on environmental conditions, Phytophthora races present in field, and the genetic resistance or tolerance of soybean variety.  Yield losses from phytophthora infection can range from 5-50% of the total crop.  To make the comparison three segregating experimental lines were grown in South America for purification purposes, plant pulls were done for the Rps1k Phytophthora gene and Rps1c Phytophthora gene.   Scoring of PRT (Phytophthora Tolerance) was done on a 1-9 scale with 1 equaling a dead plant and 9 equaling a completely healthy root system (tap root unaffected).  Scoring was based upon root growth and plant death which allowed us to assess the plant’s ability for root health and adventitious root regrowth.  This study resulted in no statistical differences between the isolines investigated, however, anecdotal observations of plant root systems did show some general tendencies.