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Root systems are crucial for optimizing plant growth and productivity. There has been a push to better understand root morphological and architectural traits and their plasticity because these traits determine the capacity of plants to effectively acquire available water and soil nutrients in the soil profile. In this study, two sets of germplasm materials were used to investigate the root system of the new oilseed crop Physaria fendleri (syn. Lesquerella fendleri) and gather preliminary information on available variability in root traits of the taxa and determine their response to temperature previously found optimal for above ground biomass development in the field. One experiment consisted of eighteen Physaria accessions grown in germination pouches for 21 days under two temperature treatments (21/13 degrees C and at 30/21 degrees C) then screened for nine root system parameters. Substantial variation in root length was found within the taxon. Apical root length was plastic in response to temperature with plants growing longer apical root zones when grown at a higher temperature and no difference in other root variables associated with temperature. The second experiment consisted of three accessions of P. fendleri and two of its sister genus Paysonia grown for 60 days in the greenhouse. Root trait analyses indicated that total root length, root length density, specific surface area and diameter differed between the two genera. Two accessions of P. fendleri, WCL-LO4 and PI 596456, were represented in both laboratory and greenhouse experiments. PI 596456 exhibited greater root:shoot ratio and root mass ratio than WCL-LO4 in both growth environments. This root trait screening in P. fendleri and Paysonia provided initial information in lesquerella as basis for future genetic and/or physiological studies relating to its root system. (C) 2014 Elsevier B.V. All rights reserved.