Culm Length and Differential Development of the Coleoptile, Root, and Subcrown Internode of Near‐Isogenic Wheat Lines1

Abstract

Five near‐isogenic selections of winter wheat that differ in culm length and the two parental varieties were studied to compare morphohistological development of some seedling characters and to relate the developmental differences to culm length phenotype and genotype. Coleoptile length, subcrown internode length, seedling emergence rate index, total seedling emergence, and culm length were shown to be positively interrelated in most selections. Differential development of coleoptile and subcrown internode length depended generally upon differential enlargement of their parenchyma cells. The single exception to this occurred in Selection 9 where an increased rate of cell division was associated with coleoptile development, but a shortened subcrown internode was attributed to a decreased rate of cell division. On the other hand, parenchyma cell width of neither coleoptile nor subcrown internode showed any relationship with genetic differences that characterize the various near‐isogenic lines. Presence of two separate dwarfing mechanisms was indicated in the material, one of them ineffective in the seedling stage.