[Applied Genetic Studies on Cytoplasmic Pollen Sterility in Winter Rye]

Restorer test crosses of ten open-pollinated populations to CMS-line L1-P (P = 'Pampa' cytoplasm) in 1973 yielded 28 % male-fertile (mf), 27% partially male-sterile (pms), and 45 % male-sterile (ms) plants. In 1974, with CMS-tester-linie L3-P, the respective values were 7, 56 and 37 %. Significant differences between populations were found for the ms-proportions only. Averaged over the two tests they ranged from 16 to 57%.Tested to L1-P in 1971, 3 homozygous inbred lines were found to be restorers, 38 partial restorers, and 46 nonrestorers. Tested to L3-P in 1974, the respective numbers were 1,155 and 41 lines. 18 (out of 87) lines were classified in both tests as nonrestorers, but none as a restorer.Continued search for CMS sources was successful in 15 cases up to 1974. Four forms trace back to the Argentinian cultivar 'Pampa', ten to samples of Persian primitive rye and one to European adapted material.By means of diallel crosses, six genotypes (single crosses) were combined with three cytoplasms (Pampa-2 and two Persian sources). Three of the genotypes reacted equally with each of the cytoplasms: one as a restorer, one as a partial restorer, and one as a nonrestorer. The remaining combinations displayed pronounced plasmotype/ genotype interactions.Since 1971 an experiment has been in progress; to test the CMS mechanics for large scale hybrid seed production. Throughout, seed setting on the ms mother plants was similar to that on the pollinator plants. Fields were about 3 ha, and seed and pollinator parents were grown in strips 7, 50 m and 2, 50 m broad, respectively.