I. Wild Glycine species. Cytological and morphological investigations of wild Glycine species continued throughout 1979 in an effort to further characterize the species. Attempts have been made to hybridize wild Glycine species with one another in order to identify species barriers and isolate useful parents for the cultivated G. max x wild species crossing program. Great variation was found between accessions with respect to their fertility as male or female parents in crosses. Difficulties encountered so far in these crosses include hybrid inviability or sterility at the developing zygote, seed germination, seedling and mature plant stages.
Hybridization attempts within the subgenus Glycine are summarized below.
A total of 881 attempts gave 93 hybrids, with a yield of 319 seed from intraspecific and 40 seed from interspecific crosses. These together with 11 other accessions from diverse sources bring the collection of wild Glycine to a total of 232 accessions. A hybridization program involving cultivated G. max and wild Glycine was initiated in 1979. Several diploid line of G. max, including one carrying the ms1 gene for male sterility, and the early variety Altona which sets pods well under greenhouse conditions, were used as the female parents in crosses with diploid wild species. Thirteen different induced autotetraploid lines of names soybean cultivars were used as female parents in crosses at the tetraploid level.