Reproductive Cold Stress in Contrasting Sorghum Genotypes: Is Pollen Fertility Really the Crucial Trait?

Area of Science:

• Plant Science
• Agronomy
• Genetics

Background:

• Cold stress during sorghum reproduction causes significant yield loss, limiting cultivation in temperate regions.
• Understanding reproductive cold tolerance is crucial for breeding progress and enhancing yield stability.

Purpose of the Study:

• To investigate the mechanisms of cold tolerance in sorghum during the reproductive phase.
• To assess the impact of cold stress on pollen fertility and female floral organ receptivity.

Main Methods:

• Comparative analysis of cold-tolerant and cold-sensitive sorghum lines and their reciprocal F1 hybrids under cold stress.
• Pollen viability assessment using impedance flow cytometry.
• Determination of panicle harvest index post-maturation.

Main Results:

• The developmental stage from generative tissue formation until BBCH39 (flag leaf visible) is the most sensitive to cold stress.
• Evidence suggests female floral organs may be more affected by cold stress than previously understood, impacting seed set.
• No significant maternal or paternal effects were observed in the inheritance of cold tolerance in reciprocal F1 hybrids.

Conclusions:

• Findings highlight the critical cold-sensitive developmental window in sorghum reproduction.
• Identifies female floral receptivity as a key factor in cold-induced yield loss.
• Provides insights for developing cold-tolerant sorghum varieties for wider cultivation and improved yield stability in temperate climates.