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Agronomy QUESTION #2103
Question 1
The process of vernalization in cereal crops (wheat, barley) refers to:
  • The application of external nitrogen fertilizer to promote vegetative growth in spring
  • The acquisition of competence to flower by exposure to a prolonged period of cold temperature (1–10°C for 4–8 weeks), which epigenetically silences floral repressor genes (VRN2) and activates floral promoters (VRN1) — ensuring reproductive development occurs in spring rather than autumn✔️
  • Hardening of seedlings by gradual exposure to low temperatures to improve frost tolerance
  • The process of selecting winter-hardy genotypes for spring planting
Correct Answer Explanation
Vernalization is a cold-temperature requirement for flowering in winter annual crops. Epigenetically, cold induces chromatin remodeling (H3K27me3 modifications) that permanently silences FLC (in Arabidopsis) or VRN2 (in cereals), derepressing floral integrator genes. Without vernalization, winter wheat planted in spring remains vegetative. The VRN1, VRN2, VRN3 gene system controls vernalization response and is a major target in breeding for climate adaptation.