Experiment Station Record, Volume 92, January-June, 1945 Page: 354
xiii, 1010 p. ; 24 cm.View a full description of this book.
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354 EXPERIMENT STATION RECORD [Vol 92
dominant cumulative factors, B1 and B2;' and have classified 160 varieties and
strains of cotton on the basis of blackarm resistance and described the type of
resistance inheritance obtaining in certain American crosses.2 In the present installment
it is shown that BAR 3-a strain of G. punctatum showing grade 1-2 resistance
(0 = immunity and 12 full susceptibility)-contains two linked blackarm
resistance genes Ba and B3, B2 being the gene for resistance in hirsutum varieties
and B3 a new semidominant factor conferring grade 7.1-8.1 resistance on Sakel
(G. barbadense) when heterozygous and grade 4.1-7.1 when homozygous. Neither
minor nor modifying factors in BAR 3 are sufficiently strong to have any marked
effect. Bs and Ba are additive, B2b2B3bs and B2B2B3b3 plants showed resistance of
about grade 4. B2b2BaB3 and BaBB3Bs plants showed grade 3 resistance when the
factors were transferred to a Sakel genotype. B3 and B1 (the latter derived from
Uganda B 31) also showed marked additive effect, BiB1Bsb3 and BablBsb3 Sakel
plants possessing grade 4-6 resistance.
Factors Ba and B3 are linked and showed 32.4 percent cross-overs in the first four
backcrosses, with a resistant : susceptible ratio of 1.96 : 1 against a 3 : 1 dihybrid
expectation. The straight F3 and F2 of early backcrosses gave good approximation
to the 7.8 : 1 ratio expected with 32.4 percent cross-over, except that some families
in the straight F2 showed the repulsion ratio. Later backcrosses and later backcross
F2 showed a loss of linkage attributed to replacement of the punctatum segment
of chromosome between B2 and Bs by barbadense, thus permitting greater
freedom of crossing over and making the recombination value approach 50 percent.
The resistance of Gambia Native, another punctatum strain, is also due to Ba and
Bs, but Gambia possesses, in addition, a number of minor factors, and crosses between
Gambia and Sakel showed blending inheritance in F2. Both resistant and
susceptible strains of Hindi Weed cotton occur. Resistant selections contained B2
unaccompanied by weak factors; B2 in the Hindi genotype produced a slightly
heightened resistance attributed to modifying factors. Darfur Local, a cultivated
punctatum from the western Sudan, was heterogeneous for resistance but gave evidence
of the presence of B3 and, assumedly, also of B2. Kadugli Local, a semiwild
punctatum from Sudan, showed marked (grade 4) resistance, but no genetical
analysis has yet been made.
De mogelijkheid van de kruising Solanum tuberosum 9 X S. chacoense /,
C. KAPENGA (Genetica ['s Gravenhage], 23 (1943), No. 5-6, pp. 537-538, illus. 1;
Eng., Ger. abs., p. 538).-Report of a successful cross (1941): S. tuberosum 9 and
S. chacoense $, using the varieties Roode Star and Epicure as mother plants.
A comparison of Sweet Spanish hybrids with commercial Sweet Spanish
onion strains, A. M. BINKLEY and H. A. JONES. (Colo. Expt. Sta. coop. U. S.
D. A.). (Amer. Soc. Hort. Sci. Proc., 44 (1944), pp. 485-487, illus. 1).-A number
of lines have been isolated in both the Utah Sweet Spanish and Colorado No. 6 onions
that produce 100 percent male-sterile progenies. The male-sterile lines are being
crossed with desirable male-fertile lines to produce desirable hybrids. Comparative
yield tests of certain new hybrids and commercial varieties showed most of the
hybrids to be in the same yield classes as their commercial parent. One hybrid, No.
153, gave a significantly higher yield. Further improvements are expected when a
large number of inbred lines are available for crossing.
Studies in the genetics of the onion (Allium cepa L.), H. A. JONES, A. E.
CLARKE, and F. J. STEVENSON. (U. S. D. A.). (Amer. Soc. Hort. Sci. Proc., 44
(1944), pp. 479-484).-The following recessives observed in onion crosses are
described: Albino seedling; yellow seedling, linked with glossy; yellow seedling;
not linked with glossy; pale green seedling; virescent seedling; glossy foliage; exJour.
Genet., 38 (1939), No. 1-2, pp. 133-159, illus. 9.
2Jour. Genet., 41 (1941), No. 2-3, pp. 391-409, illus. 3.
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U.S. Department of Agriculture. Agricultural Research Administration. Office of Experiment Stations. Experiment Station Record, Volume 92, January-June, 1945, book, 1947; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc5064/m1/367/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.