Estimates of Combining Ability and Heterosis in Converted Exotic Sorghums¹

Abstract

The agronomic performance and breeding behavior of 11 restorer lines (R‐lines) derived from sorghum (Sorghum bicolor L. Moench) conversion program materials were evaluated in four environments in Iowa. Data for grain yield and the primary components of yield were obtained from single crosses and three‐way hybrids involving the R‐lines as male parents.For both types of hybrids, general combining ability (g.c.a.) effects of the R‐lines accounted for the largest portion of the variation expressed for grain yield, heads/plant, 100‐seed weight, and seeds/head. Significant tfcts for g.c.a. (females) were expressed for all characters in the single crosses, but this effect was significant only for seeds/head in the three‐way hybrids. Variation attributable to specific combining ability (s.c.a.) effects provided the smallest contribution to the inheritance of all traits in both types of hybrids.Heterosis for grain yield was greater than that for any of the components of yield. Mean heterosis and hetcrobeltiosis for yield in the single crosses averaged 49 and 37%. In average performance with all females, the single crosses with 10 of the 11 R‐lines exceeded the mean yield of the check hybrid ‘RS 610’.

Hybrid performance of sorghum and its relationship to morphological and physiological traits under variable drought stress in Kenya

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and Pickett 1966, Laosuwan andAtkins 1977) and/or semi-arid Sorghum, Sorghum bicolor L. Moench, is grown mostly in semi-arid growing conditions (Jowett 1972, Kapran et al 1997). climates where unpredictable drought stress constitutes a major pro-Adaptation to drought stress may include drought escape, duction constraint.

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Estimates of combining ability of S2 families derived from the random-mating sorghum population IAP1R

“…That method also has been used to alter the hydrocyanic In sorghum, Conner and Karper (1927) were among the first to observe that certain sorghum hybrids produced greater grain yields than their parents. Since that study, other studies with sorghum have shown that certain hybrids surpass their parents for grain yield (Karper and Quinby, 1937;Bartel, 1949;Stephens and Quinby, 1952;Quinby et al, 1958;Kambal and Webster, 1966;Niehaus and Pickett, 1966;Kirby and Atkins, 1968;Malm, 1968;Collins and Pickett, 1972;Laosuwan and Atkins, 1977;Wilson et al, 1978;Monyo et al, 1988). Heterotic manifestation also have been observed for increased plant height (Conner and Karper, 1927;Karper and Quinby, 1937;Bartel, 1949;Quinby et al, 1958;Kambal and Webster, 1966;Niehaus and Pickett, 1966;Kirby and Atkins, 1968;Laosuwan and Atkins, 1977)…”

Comparisons of agronomic traits in the initial and advanced cycles of IAP3BR(M) random-mating grain sorghum population

“…That value is approximately three times the 4.9% that was estimated by Lothrop (1983) for lAPlR sorghum population. Malm (1968) and Laosuwan and Atkins (1977) evaluated the performance of hybrid sorghums that involved either unadapted or exotic parental materials and found that additive gene effects were of major importance in the inheritance of seed size. However, investigations that involved parents that were more adapted to the area in dicated that nonadditive gene action also contributed appre ciably to the expression of seed size (Niehaus and Pickett, 1955;Beil and Atkins, 1957;Liang and Walter, 1968) Comparisons of the heritability estimates and genetic vari ances determined from the CO and C4 data may provide answers to these questions.…”