3. Tassel-seed 3 and tassel-seed 6 - The results of tests reported in the 1940 News Letter by Lindstrom and by me suggest that Ts3 is between an and gs, while Ts6 is near bm2 and probably to the right. The records reported by Lindstrom, tho conclusive in showing that Ts6 is near bm2, are inconclusive with respect to whether Ts6 is to the right or the left of bm2. Where one region is as long as that between br and bm2 and the other as short as bm2 to Ts6, double crossovers are apt to be as frequent as are singles in the short region. My last year's records, involving an and either gs or bm2 are unsatisfactory because of the wide differences between complementary classes of crossovers. The records presented here are equally unsatisfactory for the same reason. They are given first in a table as 4- and 5-point tests with complementary crossover classes combined.
|Four- and five-point tests with Ts3 and Ts6|
The data, as presented in the accompanying table indicate that js3 is between an and gs, and Ts6 near bm2 and to its left. The unsatisfactory nature of the data is well shown when arranged as 2-point tests involving an and either js3 or Ts6, as follows:
In the cultures involving Ts6, an was strikingly and Ts6 somewhat deficient. In the Ts3 cultures, an was slightly and Ts3 decidedly deficient. The striking feature of these records, however, is the discrepancy between complementary crossover classes, ++ to an Ts6 being over 3 to 1 and ++ to an 10 to 1.
It seems likely that some, perhaps many, plants recorded as +Ts6 may have been an Ts6. The tassels were not removed and in many cases, ears failed to develop, and it is difficult to determine an from the tassels alone of Ts6 plants. With a3 and an, experience of some years has led me to question whether there may be an inhibiting effect such that, when heterozygous Ts3 and homozygous an are together, both characters generally fail to develop. But no adequate test of such a notion has been attempted.