7. Seedling leaf necrosis.

A type of seedling character has been found in our radiation studies which shows early necrosis of the leaves. The seedlings are green and normal looking for several days, usually long enough to have two leaves fully expanded. Then the leaves suddenly collapse and dry up. The seedlings remain alive and some may shoot out another leaf which quickly suffers the same fate. After a time the seedlings die. One such necrotic was associated with an induced translocation involving chromosomes 5 and 9. Eighty‑five self ears were obtained from outcrosses to standards. These were distributed as follows:

Semisterile	segregating necrotic	40
Normal	normal	40
Semisterile	normal	3
Normal	segregating necrotic	2

This indicates 6 per cent crossing over between necrotic and the translocation but does not identify whether the gene is in chromosome 5 or 9. The break points in the two chromosomes are 5 S.25 and 9 S.25.

E. G. Anderson and H. J. Teas