CYTOGENETIC STUDIES IN THE TRIBE TRITICEAE

Abstract

From morphological, physiological and cytogenetical studies of ten different interspecific tetraploid and hexaploid hybrids among five Japanese, two Nepalese and an American species of Agropyron, the following results were obtained.1. Most of the interspecific F1 plants are vigorous and in general the characters in F1 are either intermediate between the parents or superior to those of the parents.2. Complete pollen sterility and high seed sterility were the rule in all combinations examined.3. From chromosome pairing in F1 hybrids, it is concluded that (1) two genomes of Japanese tetraploid species, Ag. ciliare and Ag. yezoense, are very similar, (2) two Japanese hexaploid species, Ag. humidum and Ag. tsukushiense, have quite identical genomes, (3) genomes of a Nepalese tetraploid species, Ag. semicostatum, are closely related to those found in Japanese tetraploid species, and (4) an American tetraploid species, Ag. trachycaulum, possesses genomes distantly related to those of Japanese tetraploid species.