2. Photoperiodic effect on corn grass (CG/+).
In last year's News Letter, it was reported that Corn Grass plants show a remarkable response to length of day. These results were repeated in 1949. Plants grown from the October 1 planting produced few tillers, were upright in growth and produced tassels that shed good pollen, whereas the September 15 sowing produced typical Corn Grass plants with many tillers and no tassels. All plants were grown with no supplemental light. The change in type of growth took place earlier in 1949 (October 1) than in 1948 (November 1) although in the October 15, 1948 planting there was a more or less intemediate type. In 1949 plants were all crosses of Mangelsdorf's multiple tester and Corn Grass, while those in 1948 were from open pollinated Corn Grass pollinated by normal corn.
In the 1948 fall crop, the tall type of plant persisted for only two sowings. November 1 and 15 and plants from the two December sowings produced almost normal Corn Grass with the exception that a few tassels were produced. The January 1 sowings resulted in completed normal Corn Grass plants with no tassels.
Perhaps modifying genes have been introduced into the Corn Grass plants causing some tassel formation in the field in the summer of 1949. Thus it was possible to make a considerable number of controlled crosses more easily with different linkage testers and it should be possible to establish linkage with this gene fairly soon. Pollen of Corn Grass was put on Teopod ears to determine if these two dominant genes are allelic. Corn Grass has some of the characteristics of Teopod but is much more striking and shows a greater difference from normal corn than Teopod.
W. Ralph Singleton