Rapid expansion of leaves of early-stage plants in wheat produced by chromosomal control of characteristics related to rapid expansion of the first six leaves of wheat were investigated using a set of single chromosome substitution lines under two different temperature regimes(TRs).Results from this study indicated that several chromosomes could be responsible for each of the four characteristics studied(including leaf width,leaf length,leaf elongation rate and leaf appearance index)and that different chromosomes may be responsible for the same characteristics at different TRs.Only a small number of substitutions that showed the most significant effects on leaf length were found among those that showed the most significant effects on leaf width,providing further evidence that these two characteristics are likely controlled by different sets of genes.Substitutions 4B,4D,and 5A are among those that were repeatedly detected to having significant effects on different leaf characteristics at the lower-TR and genes residing on these three chromosomes could be homologous.This possibility and its implication are discussed.