Stand Reduction Studies in Type II Dry Beans.

Proper crop loss assessment due to stand reduction damage requires evaluation of newer Type II dry bean cultivars to this type of physical injury since yield loss charts are currently based on Type I and Type III cultivars.  The study objective was to determine the effects of cultivar, growth stage, and stand reduction on yield and yield component response of Type II dry bean cultivars.  The study was conducted at Carrington, Johnstown, and Prosper, ND during 2006 and 2007.  Standard agronomic practices were applied for dry bean production. The experiment was a RCBD with a split plot arrangement where cultivar was the main plot, and the subplot was a factorial combination of grow stage of treatment and stand reduction level.  Great northern cultivar Matterhorn and pinto cultivar GTS900 each with plant Type II display were subjected to 0, 25, 50, 75, and 90% stand reduction at growth stages V2, R1, and R3.  Results indicated yield reduction increased as growth stage advanced and stand reduction increased.  Pods per plant was the yield component most affected by the treatments and increased as stand reduction increased.  However, as stage of treatment advanced pods per plant increased less as stand reduction increased.  There were not any interactions with cultivar implying cultivars responded similarly to the treatments and a common loss chart could be developed for Type II cultivars.