Hunt Institute Archives Text Discovery Platform

Page transcription

14 NN
14 N

Seeds of the June crop germinated, whereas 24 seeds of the latter crop germinated, though only two plants survived to flowering. They were, initially, highly sterile; although most of the 28 divisions were regained at meiosis, it was possible to observe from five to nine bivalents at metaphase. I interpreted this as indicating that one chromosome of the Agropyron chromosome might occur, although it was not also that one chromosome was lost by the other. Studies of the tetraploid Agropyron plant had shown the occurrence of quadriverts that I interpreted as indicating autogamy, so I took the occurrence of more than two bivalents in the hybrid to mean that one autogamy of the Agropyron chromosomes occurred whereas I explained the occurrence of 5-7 bivalents as indicating that one of the two haploids of the Elymus species must be identical or closely related to the two Agropyron haploids. I believe this conclusion was supported by the much later discovery of 5-7 bivalents on hybrids between Elymus mollis and Agropyron from the diploid Agropyron domesticum produced in 1936 by aid of my students on a greenhouse in Diddel in the early sixties. It is interesting to point out that this is another story.

These first experiments convinced me that any successful experiment in producing intergeneric allopolyploids, or the wheatgrass, must be preceded by detailed taxonomical studies (by cytogenetical analyses of the kind done by Vavilov and his associates in their studies of relationships of the wheats of Azilops, etc., by aid of exact analyses of the karyotypes of species and their races, so that unnecessary crossing of the haploid types could be avoided.

We moved to the tropics in the beginning of 1957, to the heart of the Gambia, Whiting in the heart of the Sudan, which in 1957, although excellent facilities were limited, as at most botanical institutions in Africa, we accepted this as a challenge to undertake, with considerable success, the studies that had begun in 1956. I feel a great deal of a personal interest in the general review of the wheatgrasses as a whole. Although these grasses are mainly African, they have been widely introduced into North America for various purposes, and there are easily available from experimental stations and seed exchanges. We made plans for close study of certain of these grasses, and received their great taxonomic help. In the first stage (June 1957), we sent our graduate students in Virginia and later Patrick studied certain critical groups (Chenopodium, Salsola, etc.). But our incomplete investigations were left unexplored except for certain partial exclusions (Line 1, Line 2, Line 3, etc.), at the same time as we followed the promising results of independent studies of the tribe Agropyron (Bosson, etc.).