Fig. 1. Minimum and maximum air temperatures and precipitation from 1 July through 30 September at the Rice Research Extension Center (RREC) and Northeast Research and Extension Center (NEREC) during 2003, 2004, and 2005. Precipitation amounts >40 mm were entered as 40 mm. Temperature and precipitation data were obtained from the National Climatic Data Center (2006) for weather stations located at Stuttgart, AR and Keiser, AR. The average date of 50% heading is denoted by an open triangle.