A pot experiment and a field experiment were conducted at the same time, between December 2008 and May 2009. The pot experiment was undertaken in an open air environment at the Field Crop Research Station of Khon Kaen University, Khon Kaen province, Thailand (latitude 16◦28N, longitude 102◦48E, 200 m asl), while the field experiment was carried out in a farmer’s field in the same general locality. During the course of the study, climatic conditions were generally dry, with mean maximum and minimum temperatures of 33.8 ◦C and 22.2 ◦C, respectively, daily pan evaporation of between 0.4 and 9.8 mm, average relative humidity of 77.9% and solar radiation of 18.8 MJ m−2 d−1.