Genetic control of economic traits and evidence of economic heterosis in crosses involving monoecious cucumber genotypes

ABSTRACT

A cucumber (Cucumis sativus L.) hybrid could be acceptable to growers of tropical and subtropical climates if it is a high yielder with good fruit quality, and has tolerance against downy mildew disease. Six phenotypically diverse parents were crossed in half-diallel mating design to determine the extent of heterobeltiosis and standard heterosis, mode of gene action, combining ability effects, and dominance effects for 15 quantitative characters to produce information that could lead to development of improved genotypes. The predictability ratio indicated response of non-additive gene action in controlling expression of most traits under study. Two genitors ‘Debstar’ and ‘Pusa Barkha’ could be potential donors in breeding. The crosses ‘Debstar × Pusa Barkha’ and ‘Pusa Barkha × Samrat 7 Star’ were identified as having promise based on average values, heterobeltiosis and standard heterosis manifested, and relevance of specific combining ability effects, for possible commercialization in cucumber growing zones of tropical and subtropical climates after critical testing. Isolation of pure lines from the segregating generation of heterotic F₁s is an alternative approach to improve fruit yield, fruit quality, and downy mildew disease tolerance. Partial- to overdominance response in inheritance of most traits contributes to the genetic basis of heterosis. A commercially useful downy mildew tolerant hybrid with involvement of a single genotype tolerant to this disease might be able to be developed.

KEYWORDS:

• Cucumis sativus
• combining ability
• downy mildew
• dominance effect
• gene action
• heterobeltiosis
• standard heterosis

Acknowledgments

The work supported with partial financial assistance provided by the Indian Council of Agricultural Research – Indian Institute of Vegetable Research, Varanasi, India.