Evaluation of Several Soybean Cultivars for Differences in Trifoliate-Leaf Boron Concentration

Fourteen cultivars included in the University of Arkansas Soybean Variety Testing Program were selected for evaluation based on their tolerance to Roundup herbicide (Roundup Ready® or Conventional) and their ability to include or exclude chloride (Table 1). Trials conducted at the Cotton Branch Experiment Station (CBES) near Marianna, Ark., and the Rice Research Extension Center (RREC) near, Stuttgart, Ark., were selected because soybean yield trials were irrigated and grown on silt loam soils (Table 2). The soil at CBES was a Calloway silt loam and at the RREC the soil was a Dewitt silt loam. Boron deficiency of soybean has not been documented at either location. Additional information on the soybean yields, cultivar traits, precipitation, and general management of trials conducted in 2002 were described by Dombek et al. (2002). Cultivars included five Roundup Ready® and nine conventional cultivars. Chloride screening reports from the 2001 Soybean Variety testing results were used for the initial selection of Cl sensitivity (Dombek et al., 2002). However, Cl sensitivity data in the 2000 and 2002 reports (Dombek et al., 2000; 2001) showed different results for some cultivars. Cultivars that were reported as ‘Cl includers’ or ‘Cl excluders’ for both years were identified as such; however, cultivars that were initially identified as includers or excluders and changed between years were labeled as ‘Cl segregators’. Although cultivars are identified as Roundup Ready® or conventional, Roundup® herRESEARCH PROBLEM