SUPERNUMERARY CHROMOSOMES IN SYNTHETIC POPULATIONS OF CRESTED WHEATGRASS, AGROPYRON DESERTORUM

Twelve experimental synthetics were formed from plants with various frequencies of supernumerary chromosomes and multiplied through three generations. Chromosome counts were made of representative samples of these populations in all generations.Synthetics formed from plants free of supernumerary chromosomes remained relatively free of them through three generations. Where basic plants showed supernumeraries the mean chromosome numbers of the populations increased in the first and second generations, and decreased in the third generation. Three synthetics with the lowest number of supernumerary chromosomes showed a decrease in the mean chromosome numbers.