Butler, L.
In previous years, germination tests have been conducted on seed from Wo/+ plants. These results have shown that the seed germinated (91%, 93% and 97%) just as well as that from +/+ plants, which proves that seeds of the genotype Wo/Wo are not usually formed. In some cases where extremely wooly seedlings are produced which do not form a plumule, it appears that the lethal has been rendered inoperative during the formation of the seed. The main evidence for this comes from one lone planting, where instead of getting none or few of these plumuleless seedlings, I got 39. There were 250 seeds planted in the flat and the segregation was: 39 Wo/Wo (?):131 Wo/+ : 69 +/+. The gene Xa produces its lethal effect in the seedling stage, so the better the germination the greater the number of Xa/Xa Plants which germinate and then die, and also the more Xa/+ plants which appear. This is documented in previous comunications. The mutant ro is allways deficient, and when a controlled germination test was conducted, the following results were obtained: 350 seeds planted gave 276 + : 59 ro. This is a germination of 95.7%, and if all the non-germinating seeds are regarded as of the rojro genotype. then the ratio should have been 276 : 74, which gives a chi square of 2.78. Thus it appears that the lethal effect of the ro gene is produced mostly in the seed, but unfortunately this experiment is not conclusive.