Seed Processing

• Statement (I) is True: Single cross hybrids ($A imes B$) combine two completely inbred, homozygous lines, maximizing specific combining ability (SCA) and total genetic homogeneity; hence, they achieve the highest theoretical yield potential and absolute uniformity among all hybrid types.
• Statement (II) is True: Double cross hybrids ($(A imes B) imes (C imes D)$) contain broader genetic heterogeneity across individuals, conferring superior developmental homeostasis, wider climatic and edaphic adaptability, and greater buffering capacity against biotic and abiotic stresses compared to uniform single crosses.
• Conclusion: Both Statement (I) and Statement (II) are true (Option 1).

Correct option: (1) Both Statement (I) and Statement (I) are correct

• Induction of Staminate Flowers in Gynoecious Lines: Gynoecious cucumber lines (Cucumis sativus) produce only pistillate (female) flowers, preventing natural selfing.
• Maintenance: Foliar application of Silver Nitrate ($AgNO_3$) or Silver Thiosulfate (STS) acts as a potent inhibitor of ethylene action, inducing transient male (staminate) flowers that produce viable pollen for self-pollination. (Correct answer: Option 1)

• Two-Line Hybrid Seed Production: A hybrid breeding system that eliminates the need for maintainer (B) lines by utilizing environmentally sensitive genic male sterility (EGMS—TGMS or PGMS) or functional male sterility.
• Commercial Feasibility: Successfully established and commercially exploited in Brinjal (Solanum melongena) utilizing functional male sterility (positional sterility/exserted stigma) or TGMS systems. (Correct answer: Option 1)

• Comprehensive Definition of Pre-Breeding: Pre-breeding refers to all activities designed to identify desirable traits and genes from unadapted exotic materials and crop wild relatives (CWR) and transfer them into intermediate breeding populations.
• Key Dimensions:
• Identification and characterization of novel traits not found in the cultivated gene pool.
• Transfer of genes to broaden the genetic base of modern cultivars.
• Overcoming severe linkage drag and sexual hybridization barriers through backcrossing and marker selection.
• Conclusion: Statements 1, 2, and 3 are all integral components of pre-breeding. (Correct answer: Option 4)