Correlated Genetic Response in Pumpkin Genotypes Selected under Low Income Conditions

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Cucurbit Genetics Cooperative Report 21:66-66 (article 25) 1998

Humberto Rios Labrada, Antonio Fernandez Almirall and Orlando Batista de la Carrera
Instituto Nacional de Ciencias Agricolas (INCA). GP no1 San Jose de las Lajas, La Habana, Cuba cp 32700

Introduction. Centralized pumpkin (Cucurbita moschata) breeding programs (CPBP) have been highly effective in producing broadly adapted varieties of hybrids for high-input production environments. However, it is widely acknowledged that the varieties and hybrids developed from CPBP have not been extensively adopted by resource-poor farmers. As Cuba is currently undergoing a crisis for agricultural resources such as fertilizer, pesticides and irrigation, differences in environmental and socio-economic conditions have increased among localities during the last few years and CPBP has not been able to satisfy their requirements. The purpose of this study was to demonstrate the importance of genetic correlated responses as a justification for selecting for specific adaptation.

Materials and Methods. Genetic correlated responses (Calhoun et al. 1994) of fruit yields for ten genotypes (Rios et al., 1998) were estimated for different stress conditions using the following four cases:

  • Case 1 (Indirect Selection). Selecting under heat stress and testing under drought conditions.
  • Case 2 (Indirect Selection) Selecting under drought stress and testing under heat conditions.
  • Case 3 (Direct Selection) Selecting under heat stress and testing under the heat conditions.
  • Case 4 (Direct Selection) Selecting under drought stress and testing under the drought conditions.

Genetic correlated responses (GCR) for Cases 1 and 2 (Indirect Selection) were 5.2 and 4.0% (Table 1). However, for Cases 3 and 4 (Direct Selection GCR’s were approximately twice (10.1 and 11.4%), despite the fact that calculated heritabilities were similar to those for indirect selection. This illustrates the importance of evaluating genotypes under low income conditions, which are associated with adaptive value (Rios, 1998).

These results, with regard to the role of direct selection, are similar to those reported by Ceccarelli (1994) and Atlin (1997). They appear to be highly applicable to Cuban pumpkin response, since direct selection or local varietal selection would increase the selection efficiency for genetic advance with low heritability traits.

Table 1: Genetic correlated response for different types of stress.

Type of selection

Selection environ.

Target environ.

Genetic correlation

Genetic response corrrelated
Indirect selection Case 1 Heat drought 0.42 5.20
Case 2 drought heat 0.47 4.20
Direct selection Case 3 heat heat 0.88 10.10
Case 4 drought drought 1.80 11.40

Literature Cited

  1. Atlin, G.N. 1997. In what situations will participatory breeding work best? International workshop entitled: “Towards a Synthesis Between Crop Conservation and Development,” 1997, Baarlo, The Netherlands.
  2. Ceccarelli, S. 1994. Specific adaptation and breeding for marginal conditions. Euphytica 77:205-219.
  3. Rios Labrada, H., A.F. Almirall and E.C. Galarraga. 1998. Tropical pumpkin (cucurbita moschata Duch) for marginal conditions: Breeding for stress interactions. Plant Genetic Resource Newsletter. no. 113:1-4.
  4. Rios Labrada, H. 1998. Seleccion de cultivares de calabaza en condiciones de bajos insumos. PhD Thesis. National Institute of Agriculture Science. La Habana: 100p.