F₂ Hybrids of Host Plant Germplasm and Cotton Cultivars: I. Heterosis and Combining Ability for Lint Yield and Yield Components

Abstract

Although pest‐resistant cotton (Gossypium hirsutum L.) germplasm is available, it is generally not equal to adapted cultivars and other elite germplasm in yield. Cotton F2 hybrids could provide a means to combine beneficial traits of high‐yielding adapted cultivar (elite) germplasm with those of pest‐resistant germplasms. In the F2 heterosis and combining ability were studied for lint yield and the primary yield component boll number as well as for the secondary yield components of lint percentage and boll weight. These F2 hybrids were produced following a North Carolina Design II mating scheme involving four cultivars as female parents and 16 germplasm lines as male parents. The 64 F2 hybrids and 20 parents were evaluated in four environments. General combining ability (GCA) effects for various parents differed significantly. ‘Delcot 344’ gave significant, positive GCA effects for all traits studied. Significant, positive specific combining ability (SCA) effects were smaller and less significant than GCA effects. Heterosis of the F2 over the high‐parent was observed in six (9% of all F2 hybrids) F2 hybrids. In the terms of combining ability for yield, the best two parents were Delcot 344 and ‘Coker 315’. The heterosis for yield of F2 hybrids resulted mainly from increased boll number, boll weight, or a combination of both, rather than increased lint percentage. Interaction of GCA and SCA with environments indicated that F2 hybrids must be evaluated separately in each environment in which they are to be grown. These results suggest that high yielding F2 cotton hybrids can be developed that may contain acceptable levels of pest resistance.

Genetic effects on morphological and yield traits in cotton (Gossypium hirsutum L.)

“…Parents with dominant genes were responsible for increased lint % in both generations. The present results are also in line with the findings of Tang et al (1993), McCarty et al (1996McCarty et al ( , 2004a, Hussain et al (1999), Ahmad et al (2003b), Yuan et al (2005), Aguiar et al (2007) and Ali and Awan (2009), who reported additive type of gene action with partial dominance for inheritance of lint%. However, Tang et al (1996), Godoy and Palomo (1999), Basal and Turgut (2005), Iqbal et al (2005), Mei et al (2006), Esmail (2007 and Gamal et al (2009) concluded non-additive type of gene action with over-dominance for lint %.…”

“…These results confirm the findings of Iqbal et al (2005) who reported overdominance type of gene action for seed cotton yield. However, Tang et al (1993), McCarty et al (1996), Ahmad et al (1997), Godoy and Palomo (1999), Hussain et al (1999), Khan (2003), Lukonge (2005), Wu et al (2006), Aguiar et al (2007), Lukonge et al (2007) and Khan et al (2007) reported additive type of genetic control for seed cotton yield. The discrepancies with respect of phenotypic manifestation of this complex parameter might be due to different cultivars used under different environmental conditions.…”

“…Consequently, the use of genotypes with desirable genetic components of variance is a prerequisite for synthesis of physiologically efficient and genetically superior genotypes showing promise for increased production per unit area under a given set of environments (Khan et al, 2009a). To achieve these objectives using quantitative genetics, workers have advocated a comprehensive study of assumptions of additive-dominance model (through different scaling tests), genetic mechanism and genetic components of variation which control the various plant characters in parents and their cross combinations under various environmental conditions (Hayman, 1954;Mather and Jinks, 1982;Tang et al, 1993Tang et al, , 1996McCarty et al, 1996McCarty et al, , 2004aHussain et al, 1999;Khan, 2003;Ragsdale, 2003;Lukonge, 2005;Mei et al, 2006;Wu et al, 2006;Esmail, 2007;Lukonge et al, 2007;Khan et al, 2007Khan et al, , 2009aAguado et al, 2008;Ali et al, 2008;Ali and Awan, 2009;Basal et al, 2009;Gamal et al, 2009).…”

Cytoplasmic and Combining Ability Effects on Agro-Morphological Characters in Intra and Inter Crosses of Pima and Upland Cottons (G.Hirsutum and G. Barbadense)

“…Baloch et al (1995) revealed the importance of specific combining ability for yield, 100-seed weight and lint percentage, and general combining ability for boll number per plant and lint percentage. Wilson (1991) : Tang et al(1993) and Nadeem et al (1998) reported significant general and specific combining ability effects for lint yield, lint percentage, seed cotton weight per boll and boll number per plant.…”

Heterosis and Inbreeding Depression in F<sub>2</sub> Populations of Upland Cotton (<i>Gossypium hirsutum</i> L.)

“…Previous findings are also of view about the F 2 hybrids heterosis in cotton [7]. On the other hand, a group of physical properties can play a vital role in determination of textile use and economic value of cotton.…”