SUMMARYSuper-sweet maize (shrunken2,sh2) has a longer post-harvest life than standard sweetcorn (sugary1,su1), but is less well-adapted to cold conditions. The objective of the present work was to determine if the replacement ofsu1bysh2alters the combining abilities of sweetcorn inbreds for adaptation to early planting under cold conditions. Two diallel sets ofsu1andsh2near-isogenic inbred lines were evaluated in a cold chamber and by early field planting. For most of the traits related to adaptation, except silking date, there were significant mutant×genotype interactions and the estimates of general combining ability (GCA) of each version of the same inbred were different, probably due to epistasis. Therefore, to widen the genetic base of the super-sweet germplasm for adaptation, conversion of the earliestsu1inbreds tosh2, ignoring other characteristics such as emergence or early vigour in early planting or cold tests, is proposed.