Principles of Plant Genetics and Breeding

326 CHAPTER 17
could be an effective approach toward the development of drought-tolerant forage or turf-type bluegrass. Continued hybridization,
breeding, and selection of this these hybrids may provide an indigenous, productive, and drought-tolerant cool-season
perennial grass for pastures or rangelands.
References
Bradshaw, J.E., R.L. Wastie, H.E. Stewart, and G.R. Mackay. 1995. Breeding for resistance to late blight in Scotland. In:
Phytophthora infestans 150 (Dowley, L.J., E. Bannon, L.R. Cooke, T. Keane, and E. O’sullivan, eds), pp. 246–254. EAPR
Pathology Section Conference. Boole Press Ltd and Teagasc, Dublin, Ireland.
Carputo, D. 1997. Ploidy and endosperm balance number (EBN) manipulations for germplasm introgression from 1EBN Solanum
commersonii into 4EBN S. tuberosum. Ital. J. Agron. 1:123–128.
Huff, D.R. 1992. Apomixis in Poa. In: Proceedings of the Apomixis Workshop, February 11–12, Atlanta, GA (Elgin, J., Jr., and J.P.
Miksche, eds), pp. 20–25. USDA-ARS, Beltsville, MD.
Kellogg, E.A. 1987. Apomixis in the Poa secunda complex. Am. J. Bot. 74:1431–1437.
Kiellander, C.L. 1942. A subhaploid Poa pratensis L. with 18 chromosomes and its progeny. Svensk Botanisk Tidskr. 36:200–220.
Kindiger, B. 2004. Generation of androgenic haploids from interspecific hybridization of Poa arachnifera × Poa secunda.
Grassland Sci. 49:577–580.
Larson, S.R., B. Waldron, S. Monson, L. St John, A.L. Palazzo, C. L. McCracken, and D. Harrison. 2001. AFLP variation in agamospermous
and dioecious bluegrasses of western North America. Crop Sci. 41:1300–1305.
Silveus, W.A. 1933. Texas grasses. Classification and description of grasses. Glegg Co., San Antonio, TX.
Weising, K., H. Nybom, K. Wolff, and W. Meyer (eds). 1995. DNA fingerprinting in plants and fungi. CRC Press, Boca Raton, FL.
Williams, J.G.K., A.R. Kubelik, K.J. Livbak, J.A. Rafalski, and S.V. Tingey. 1990. DNA polymorphisms amplified by arbitrary
primers are useful as genetic markers. Nucleic Acids Res. 18:6531–6535.
Half-sib reciprocal recurrent selection
Key features The half-sib recurrent selection scheme
involves the making of S 1 plant testcrosses and evaluating
them to identify and select superior progenies.
Procedure: cycle 0
Season 1 Select and self-pollinate about 200–300 S 1
plants in each of two populations, A and B.
Season 2 Grow 200–300 of the selected S 1 progenies
and produce half sibs of population A by
crossing a number of plants with B as female,
and vice versa. Self-pollinate the S 1 plants
used in making the testcrosses. Save S 1 seed.
Season 3 Evaluate about 100 half sibs in replicated
trials. Select about 20 promising testcross
families. This is done for both populations A
and B.
Season 4 Randomly mate the plants selected from S 1
families within A and B to obtain new seed to
initiate cycle 1.
Procedure: cycle 1 Repeat cycle 0.
Genetic issues This scheme makes use of additive,
dominance, and overdominance gene action. It is effec-
tive for selecting favorable epistatic gene combinations
in the population. The change in the cross-bred mean
may be calculated as follows:
∆G (A×B) = [iσ 2 A(HSA) ]/4σ P(HSA) + [i′σ2 A(HSB) ]/4σ P(HSB)
where i and i′ are the selection intensities in populations
A and B, respectively; and σ2 A(HSA) and σ2 A(HSB) are the
additive variances for populations A and B, respectively.
Similarly, σP(HSA) and σP(HSB) are the phenotypic standard
deviations among half sibs.
Full-sib reciprocal recurrent selection
Key features Developed by Hallauer and Eberhart as
modifications of the method by Comstock and colleagues,
the full-sib method requires at least one of the
populations to be prolific. The recombination units are
half sibs (instead of S 1 families). Developed for maize,
full-sib families are produced by pairing plants from two
populations, A and B. The top ear of a plant from population
A is crossed with a plant from population B. The
lower ear is selfed to be saved as remnant seed. The same
is done for the reciprocal plant from population B, if
they have two ears, otherwise they are selfed.