Registration of Maize Inbred Line GT603

GT603 (Reg. No. GP-577, PI 659665) is an inbred line of yellow dent maize (Zea mays L.) developed and released in 2010 by the USDA-ARS Crop Protection and Management Research Unit in cooperation with the University of Georgia Coastal Plain Experiment Station. GT603 was developed through seven generations of self-pollination from the maize population GT-MAS:gk (PI 561859), which was released as a source of resistance to Aspergillus flavus Link:Fr. GT603 was initially selected from early self-pollinated lines under the experimental name GT-P50. Laboratory and field studies demonstrated that GT603 had aflatoxin levels similar to or lower than the related inbred lines GT601 (PI 644026) and GT602 (PI 644027) and the controls Mp313E (PI539859) and Mp715 (PI614819), but it matured earlier than Mp313E and Mp715. The line GT603 is phenotypically different (darker cob and kernel colors and better agronomic traits) from the related lines GT601 and GT602 although the source of resistance may be the same. In hybrid performance tests in 2005 and 2009, GT603 exhibited better combining ability and heterosis with the Stiff Stalk Synthetic (SSS) inbred (B73) than with the non-SSS inbred (Mo17) for aflatoxin level and grain yield.