| The SB1 material was backcrossed with A. intermedium
in 1965. Seed set was 0.77% which was similar to that after the first backcrossing.
A pronounced shift of cytoplasmic male sterility was observed in the amphidiploids
(AD), first substitution backcross (SB1) and second substitution
backcross generations (SB2). Average pollen sterility estimates
were 53% in the AD, 84% in the SB1 and 97% in the SB2.
Sixty-nine percent of all SB2 plants were 99-100% Pollen sterile
(SCHULZ-SCHAEFFER 1970). These data demonstrate that cytoplasmic male sterility
can be obtained in intermediate wheatgrass after a few generations. This
approach will be used in developing a hybrid intermediate wheatgrass. Another aspect of this project is the development of chromosome substitution lines in intermediate wheatgrass. The SB1 material has been selfed twice and selfing and backcrossing will be continued for several generations. This procedure will result in pairing of homologous Triticum chromosomes contributed by male and female gametes. Since the number of Agropyron bivalents in this material is less than 21, the establishment of chromosome substitution lines with Triticum bivalents should be possible. Five out of 330 (SB1) S1 plants showed increased seed set. Selection for high seed set will continue. Line SB1-33 had outstanding vigor and was taller than 'Oahe' intermediate wheatgrass, a well adapted variety. If increased seed set can be combined with these vigorous growth characteristics, a promising forage grass can be expected. Literature cited KIHARA, H: 1951. Substitution of nucleus and its effect on genome manifestation. Cytologia 16 : 177-193. LARTER, E. N. and F. C. ELLIOTT 1956. An evaluation of different ionizing radiations for possible use in the genetic transfer of bunt resistance from Agropyron to wheat. Can. J. Bot. 34 : 817-823. LOVE, R. M. and C. A. SUNESON 1945. Cytogenetics in certain Triticum x Agropyron hybris and their fertile derivatives. Amer. J. Bot. 32 : 451-456. MARKARIAN, D. 1958. Cytogenetic evaluation of the Triticum x Agropyron hybrid forage selections at Pullman, Washington. Northwest Sci. 32 : 79-88. SCHULZ-SCHAEFFER, J. 1963. Hybridization :of 8 Triticum with 3 Agropyron species. Wheat Inf. Serv. 15-16 : 26-29. SCHULZ-SCHAEFFER, J. 1970. A possible source of cytoplasmic male sterility in intermediate wheatgrass, Agropyron intermedium (HOST.) BEAUV. Crop Soc. 10 : March-April. SCHULZ-SCHAEFFER, J. and D. W. FENBERT 1969. Meiotic irregularities in Triticum x Agropyron hybrids. XI Intern. Bot. Congr., Seattle, Abstr. 193. TSITSIN, N. V. 1933. The Triticum x Agropyron: hybrids. Lenin Acad. Sci., Siberian Inst. Grain Cult., Omsk, 1-101 (Russian). (Plant Breed. Abs. 5 : 24-25. 1934). USDA. Wheat-grass hybrids combine best features of each. P.M. Release, Nov. 9, 1958 (mimeographed). VINALL, H. N. and M. A. HEIN 1937. Breeding miscellaneous grasses. In : Yearb. Agric., USDA, 1937 : 1032-1102. (Received December 9, 1969) |
| <-- Back |