August E. Kehr

Specific and general combining ability for yield in potatoes

SummaryForty-five lines were crossed to six testers to evaluate their general combining ability. These lines did not clearly represent a random selection of lines with respect to this character, though they had not undergone any formal selection in this respect. In these lines, the variance in specific combining ability exceeded the variance in general combining ability. Six or more testers are required to evaluate general combining ability in lines of this nature. The interaction of general combining ability and locations was less than the variation in SCA and locations.The variation in specific combining ability of a line was not related to the magnitude of its GCA effect.The general combining ability effects of 32 of the lines are given. Four of the better lines were B2368-4, La1859, I-1015-2 and I-1077W28-5.

Chieftain: A red-skinned potato with attractive appearance and broad adaptability

SummaryChieftain is a red potato with an attractive appearance, good yield and medium maturity. Its primary area of adaptabililty is in the North Central States. Chieftain has shown immunity to the common races of late blight, medium to high resistance to common scab, field resistance to mild mosaic, tuber resistance to stem-end browning and tuber resistance to net necrosis caused by current season leafroll. Chieftain has excellent quality after boiling but does not make acceptable chips after cold storage. The parentage of Chieftain includes Cherokee, Progress, Pontiac, Houma, Katahdin andS. acaule.ResumenLa variedad Chieftain es una papa roja con una atractiva apariencia, buenos rendimientos y madurez media. Su area primaria de adaptación es en los estados Nor-Centrales de los E.E.U.U. La variedad ha exhibido immunidad a las razas communes dePhytophthora, resistencia de media a superior a commune sarma, resistencia en el campo al mosaico, “chocolate.” de la papa (la mancha proximo al punto donde se une con el tallo) y a la necrosís causada por corriente encrespaduras de hoja. Tiene una excellente calidad después de hervir, pero no hace aceptable papas fritas después del depositado en cámaras frias. Los antecesores de la variedad incluyen Cherokee, Progress, Pontiac, Houma, Katahdin yS. acaule.

A program for breeding industrial potato varieties

SummaryA program for breeding industrial potato varieties has been described in detail. Starch analyses and dry matter determinations, germination of seed in sucrose solutions, and field selections of plants capable of maximum radiant absorption with “open” type vine growth, corrugated leaflets, and pubescence all are being employed in the breeding and selection of seedlings possessing outstanding potentialities for high starch and dry matter production. Promising seedlings are being increased and finally will be field-tested for economic production of starch per acre under intensive cultural conditions.

Abstracts of papers presented at the Forty-Third annual meeting of The Potato Association of America

B A G N A L L , R. H. A N D D. A. Y O U N G I N H E R I T A N C E OF IMMUNITY TO VIRUS S IN T H E POTATO The virus-X-immune potato variety Saco is also highly resistant or immune to potato virus S. We have tested for S-immunity, seedlings from a number of crosses of which Saco was one parent, and also from selfed Saco. Where Saco was crossed with an unrelated seedling, susceptible to both viruses S and X, we found 11o immunity to virus S. Where Saco was crossed with a seedling that, like Saco, was an X-immune offspring of Seedling 41956, a small percentage of S-immune seedlings resulted. The percentage of S-immune progeny of Saco, selfed, was substantially higher. Although the immunity to viruses S and X appears to ,be derived, in part at least, from Seedling 41956, there does not seem to be any correlation between immunity to virus S and immunity to virus X in the seedlings we have tested.

Resistance of potato to infection by mechanically introduced virus X

SummaryProgeny in the cross of susceptible X 927-3 (female) potato by susceptible B 2903-17 (male) were found to possess resistance to infection by virus X mechanically inoculated into Irish potato. Preliminary evidence indicated a close similarity to or identity with the immunity from virus X demonstrated by 41956. Examination of the pedigrees of parental lines and the pedigree of 41956 showed several similarities, but no common source of resistance was involved, unless it be the USDA Seedling 24642. Previously proposed theories of the origin of immunity from virus X were discussed, and the authors suggest that although their findings can be explained by a dominant complimentary gene theory, insufficient information is available to support either this or the recessive gene theory.